storj.io/minio@v0.0.0-20230509071714-0cbc90f649b1/docs/bucket/notifications/README.md

# MinIO Bucket Notification Guide [![Slack](https://slack.min.io/slack?type=svg)](https://slack.min.io)

Events occurring on objects in a bucket can be monitored using bucket event notifications.

> NOTE: Gateway mode does not support bucket notifications (except NAS gateway).

Various event types supported by MinIO server are

| Supported Object Event Types     |                                            |                                        |
| :----------------------          | ------------------------------------------ | -------------------------------------  |
| `s3:ObjectCreated:Put`           | `s3:ObjectCreated:CompleteMultipartUpload` | `s3:ObjectAccessed:Head`               |
| `s3:ObjectCreated:Post`          | `s3:ObjectRemoved:Delete`                  | `s3:ObjectRemoved:DeleteMarkerCreated` |
| `s3:ObjectCreated:Copy`          | `s3:ObjectAccessed:Get`                    |                                        |
| `s3:ObjectCreated:PutRetention`  | `s3:ObjectCreated:PutLegalHold`            |                                        |
| `s3:ObjectAccessed:GetRetention` | `s3:ObjectAccessed:GetLegalHold`           |                                        |

| Supported Replication Event Types                  |
| :------------                                      |
| `s3:Replication:OperationFailedReplication`        |
| `s3:Replication:OperationCompletedReplication`     |
| `s3:Replication:OperationNotTracked`               |
| `s3:Replication:OperationMissedThreshold`          |
| `s3:Replication:OperationReplicatedAfterThreshold` |

| Supported ILM Transition Event Types |
| :-----                               |
| `s3:ObjectRestore:Post`              |
| `s3:ObjectRestore:Completed`         |

| Supported Global Event Types (Only supported through ListenNotification API) |
| :-----                                                                       |
| `s3:BucketCreated`                                                           |
| `s3:BucketRemoved`                                                           |


Use client tools like `mc` to set and listen for event notifications using the [`event` sub-command](https://docs.min.io/docs/minio-client-complete-guide#events). MinIO SDK's [`BucketNotification` APIs](https://docs.min.io/docs/golang-client-api-reference#SetBucketNotification) can also be used. The notification message MinIO sends to publish an event is a JSON message with the following [structure](https://docs.aws.amazon.com/AmazonS3/latest/dev/notification-content-structure.html).

Bucket events can be published to the following targets:

| Supported Notification Targets    |                             |                                 |
| :-------------------------------- | --------------------------- | ------------------------------- |
| [`AMQP`](#AMQP)                   | [`Redis`](#Redis)           | [`MySQL`](#MySQL)               |
| [`MQTT`](#MQTT)                   | [`NATS`](#NATS)             | [`Apache Kafka`](#apache-kafka) |
| [`Elasticsearch`](#Elasticsearch) | [`PostgreSQL`](#PostgreSQL) | [`Webhooks`](#webhooks)         |
| [`NSQ`](#NSQ)                     |                             |                                 |

## Prerequisites

- Install and configure MinIO Server from [here](https://docs.min.io/docs/minio-quickstart-guide).
- Install and configure MinIO Client from [here](https://docs.min.io/docs/minio-client-quickstart-guide).

```
$ mc admin config get myminio | grep notify
notify_webhook        publish bucket notifications to webhook endpoints
notify_amqp           publish bucket notifications to AMQP endpoints
notify_kafka          publish bucket notifications to Kafka endpoints
notify_mqtt           publish bucket notifications to MQTT endpoints
notify_nats           publish bucket notifications to NATS endpoints
notify_nsq            publish bucket notifications to NSQ endpoints
notify_mysql          publish bucket notifications to MySQL databases
notify_postgres       publish bucket notifications to Postgres databases
notify_elasticsearch  publish bucket notifications to Elasticsearch endpoints
notify_redis          publish bucket notifications to Redis datastores
```

> NOTE:
> - '\*' at the end of arg means its mandatory.
> - '\*' at the end of the values, means its the default value for the arg.
> - When configured using environment variables, the `:name` can be specified using this format `MINIO_NOTIFY_WEBHOOK_ENABLE_<name>`.

<a name="AMQP"></a>

## Publish MinIO events via AMQP

Install RabbitMQ from [here](https://www.rabbitmq.com/).

### Step 1: Add AMQP endpoint to MinIO

The AMQP configuration is located under the sub-system `notify_amqp` top-level key. Create a configuration key-value pair here for your AMQP instance. The key is a name for your AMQP endpoint, and the value is a collection of key-value parameters described in the table below.

```
KEY:
notify_amqp[:name]  publish bucket notifications to AMQP endpoints

ARGS:
url*           (url)       AMQP server endpoint e.g. `amqp://myuser:mypassword@localhost:5672`
exchange       (string)    name of the AMQP exchange
exchange_type  (string)    AMQP exchange type
routing_key    (string)    routing key for publishing
mandatory      (on|off)    quietly ignore undelivered messages when set to 'off', default is 'on'
durable        (on|off)    persist queue across broker restarts when set to 'on', default is 'off'
no_wait        (on|off)    non-blocking message delivery when set to 'on', default is 'off'
internal       (on|off)    set to 'on' for exchange to be not used directly by publishers, but only when bound to other exchanges
auto_deleted   (on|off)    auto delete queue when set to 'on', when there are no consumers
delivery_mode  (number)    set to '1' for non-persistent or '2' for persistent queue
queue_dir      (path)      staging dir for undelivered messages e.g. '/home/events'
queue_limit    (number)    maximum limit for undelivered messages, defaults to '100000'
comment        (sentence)  optionally add a comment to this setting
```

Or environment variables

```
KEY:
notify_amqp[:name]  publish bucket notifications to AMQP endpoints

ARGS:
MINIO_NOTIFY_AMQP_ENABLE*        (on|off)    enable notify_amqp target, default is 'off'
MINIO_NOTIFY_AMQP_URL*           (url)       AMQP server endpoint e.g. `amqp://myuser:mypassword@localhost:5672`
MINIO_NOTIFY_AMQP_EXCHANGE       (string)    name of the AMQP exchange
MINIO_NOTIFY_AMQP_EXCHANGE_TYPE  (string)    AMQP exchange type
MINIO_NOTIFY_AMQP_ROUTING_KEY    (string)    routing key for publishing
MINIO_NOTIFY_AMQP_MANDATORY      (on|off)    quietly ignore undelivered messages when set to 'off', default is 'on'
MINIO_NOTIFY_AMQP_DURABLE        (on|off)    persist queue across broker restarts when set to 'on', default is 'off'
MINIO_NOTIFY_AMQP_NO_WAIT        (on|off)    non-blocking message delivery when set to 'on', default is 'off'
MINIO_NOTIFY_AMQP_INTERNAL       (on|off)    set to 'on' for exchange to be not used directly by publishers, but only when bound to other exchanges
MINIO_NOTIFY_AMQP_AUTO_DELETED   (on|off)    auto delete queue when set to 'on', when there are no consumers
MINIO_NOTIFY_AMQP_DELIVERY_MODE  (number)    set to '1' for non-persistent or '2' for persistent queue
MINIO_NOTIFY_AMQP_QUEUE_DIR      (path)      staging dir for undelivered messages e.g. '/home/events'
MINIO_NOTIFY_AMQP_QUEUE_LIMIT    (number)    maximum limit for undelivered messages, defaults to '100000'
MINIO_NOTIFY_AMQP_COMMENT        (sentence)  optionally add a comment to this setting
```

MinIO supports persistent event store. The persistent store will backup events when the AMQP broker goes offline and replays it when the broker comes back online. The event store can be configured by setting the directory path in `queue_dir` field and the maximum limit of events in the queue_dir in `queue_limit` field. For eg, the `queue_dir` can be `/home/events` and `queue_limit` can be `1000`. By default, the `queue_limit` is set to 100000.

To update the configuration, use `mc admin config get notify_amqp` command to get the current configuration for `notify_amqp`.

```sh
$ mc admin config get myminio/ notify_amqp
notify_amqp:1 delivery_mode="0" exchange_type="" no_wait="off" queue_dir="" queue_limit="0"  url="" auto_deleted="off" durable="off" exchange="" internal="off" mandatory="off" routing_key=""
```

Use `mc admin config set` command to update the configuration for the deployment.Restart the MinIO server to put the changes into effect. The server will print a line like `SQS ARNs: arn:minio:sqs::1:amqp` at start-up if there were no errors.

An example configuration for RabbitMQ is shown below:

```sh
$ mc admin config set myminio/ notify_amqp:1 exchange="bucketevents" exchange_type="fanout" mandatory="false" no_wait="false"  url="amqp://myuser:mypassword@localhost:5672" auto_deleted="false" delivery_mode="0" durable="false" internal="false" routing_key="bucketlogs"
```

MinIO supports all the exchanges available in [RabbitMQ](https://www.rabbitmq.com/). For this setup, we are using `fanout` exchange.

Note that, you can add as many AMQP server endpoint configurations as needed by providing an identifier (like "1" in the example above) for the AMQP instance and an object of per-server configuration parameters.

### Step 2: Enable bucket notification using MinIO client

We will enable bucket event notification to trigger whenever a JPEG image is uploaded or deleted `images` bucket on `myminio` server. Here ARN value is `arn:minio:sqs::1:amqp`. To understand more about ARN please follow [AWS ARN](http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html) documentation.

```
mc mb myminio/images
mc event add myminio/images arn:minio:sqs::1:amqp --suffix .jpg
mc event list myminio/images
arn:minio:sqs::1:amqp s3:ObjectCreated:*,s3:ObjectRemoved:* Filter: suffix=”.jpg”
```

### Step 3: Test on RabbitMQ

The python program below waits on the queue exchange `bucketevents` and prints event notifications on the console. We use [Pika Python Client](https://www.rabbitmq.com/tutorials/tutorial-three-python.html) library to do this.

```py
#!/usr/bin/env python
import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(
        host='localhost'))
channel = connection.channel()

channel.exchange_declare(exchange='bucketevents',
                         exchange_type='fanout')

result = channel.queue_declare(exclusive=False)
queue_name = result.method.queue

channel.queue_bind(exchange='bucketevents',
                   queue=queue_name)

print(' [*] Waiting for logs. To exit press CTRL+C')

def callback(ch, method, properties, body):
    print(" [x] %r" % body)

channel.basic_consume(callback,
                      queue=queue_name,
                      no_ack=False)

channel.start_consuming()
```

Execute this example python program to watch for RabbitMQ events on the console.

```py
python rabbit.py
```

Open another terminal and upload a JPEG image into `images` bucket.

```
mc cp myphoto.jpg myminio/images
```

You should receive the following event notification via RabbitMQ once the upload completes.

```py
python rabbit.py
'{"Records":[{"eventVersion":"2.0","eventSource":"aws:s3","awsRegion":"","eventTime":"2016–09–08T22:34:38.226Z","eventName":"s3:ObjectCreated:Put","userIdentity":{"principalId":"minio"},"requestParameters":{"sourceIPAddress":"10.1.10.150:44576"},"responseElements":{},"s3":{"s3SchemaVersion":"1.0","configurationId":"Config","bucket":{"name":"images","ownerIdentity":{"principalId":"minio"},"arn":"arn:aws:s3:::images"},"object":{"key":"myphoto.jpg","size":200436,"sequencer":"147279EAF9F40933"}}}],"level":"info","msg":"","time":"2016–09–08T15:34:38–07:00"}'
```

<a name="MQTT"></a>

## Publish MinIO events MQTT

Install an MQTT Broker from [here](https://mosquitto.org/).

### Step 1: Add MQTT endpoint to MinIO

The MQTT configuration is located as `notify_mqtt` key. Create a configuration key-value pair here for your MQTT instance. The key is a name for your MQTT endpoint, and the value is a collection of key-value parameters described in the table below.

```
KEY:
notify_mqtt[:name]  publish bucket notifications to MQTT endpoints

ARGS:
broker*              (uri)       MQTT server endpoint e.g. `tcp://localhost:1883`
topic*               (string)    name of the MQTT topic to publish
username             (string)    MQTT username
password             (string)    MQTT password
qos                  (number)    set the quality of service priority, defaults to '0'
keep_alive_interval  (duration)  keep-alive interval for MQTT connections in s,m,h,d
reconnect_interval   (duration)  reconnect interval for MQTT connections in s,m,h,d
queue_dir            (path)      staging dir for undelivered messages e.g. '/home/events'
queue_limit          (number)    maximum limit for undelivered messages, defaults to '100000'
comment              (sentence)  optionally add a comment to this setting
```

or environment variables

```
KEY:
notify_mqtt[:name]  publish bucket notifications to MQTT endpoints

ARGS:
MINIO_NOTIFY_MQTT_ENABLE*              (on|off)    enable notify_mqtt target, default is 'off'
MINIO_NOTIFY_MQTT_BROKER*              (uri)       MQTT server endpoint e.g. `tcp://localhost:1883`
MINIO_NOTIFY_MQTT_TOPIC*               (string)    name of the MQTT topic to publish
MINIO_NOTIFY_MQTT_USERNAME             (string)    MQTT username
MINIO_NOTIFY_MQTT_PASSWORD             (string)    MQTT password
MINIO_NOTIFY_MQTT_QOS                  (number)    set the quality of service priority, defaults to '0'
MINIO_NOTIFY_MQTT_KEEP_ALIVE_INTERVAL  (duration)  keep-alive interval for MQTT connections in s,m,h,d
MINIO_NOTIFY_MQTT_RECONNECT_INTERVAL   (duration)  reconnect interval for MQTT connections in s,m,h,d
MINIO_NOTIFY_MQTT_QUEUE_DIR            (path)      staging dir for undelivered messages e.g. '/home/events'
MINIO_NOTIFY_MQTT_QUEUE_LIMIT          (number)    maximum limit for undelivered messages, defaults to '100000'
MINIO_NOTIFY_MQTT_COMMENT              (sentence)  optionally add a comment to this setting
```

MinIO supports persistent event store. The persistent store will backup events when the MQTT broker goes offline and replays it when the broker comes back online. The event store can be configured by setting the directory path in `queue_dir` field and the maximum limit of events in the queue_dir in `queue_limit` field. For eg, the `queue_dir` can be `/home/events` and `queue_limit` can be `1000`. By default, the `queue_limit` is set to 100000.

To update the configuration, use `mc admin config get` command to get the current configuration.

```sh
$ mc admin config get myminio/ notify_mqtt
notify_mqtt:1 broker="" password="" queue_dir="" queue_limit="0" reconnect_interval="0s"  keep_alive_interval="0s" qos="0" topic="" username=""
```

Use `mc admin config set` command to update the configuration for the deployment. Restart the MinIO server to put the changes into effect. The server will print a line like `SQS ARNs: arn:minio:sqs::1:mqtt` at start-up if there were no errors.

```sh
$ mc admin config set myminio notify_mqtt:1 broker="tcp://localhost:1883" password="" queue_dir="" queue_limit="0" reconnect_interval="0s"  keep_alive_interval="0s" qos="1" topic="minio" username=""
```

MinIO supports any MQTT server that supports MQTT 3.1 or 3.1.1 and can connect to them over TCP, TLS, or a Websocket connection using `tcp://`, `tls://`, or `ws://` respectively as the scheme for the broker url. See the [Go Client](http://www.eclipse.org/paho/clients/golang/) documentation for more information.

Note that, you can add as many MQTT server endpoint configurations as needed by providing an identifier (like "1" in the example above) for the MQTT instance and an object of per-server configuration parameters.

### Step 2: Enable bucket notification using MinIO client

We will enable bucket event notification to trigger whenever a JPEG image is uploaded or deleted `images` bucket on `myminio` server. Here ARN value is `arn:minio:sqs::1:mqtt`.

```
mc mb myminio/images
mc event add  myminio/images arn:minio:sqs::1:mqtt --suffix .jpg
mc event list myminio/images
arn:minio:sqs::1:amqp s3:ObjectCreated:*,s3:ObjectRemoved:* Filter: suffix=”.jpg”
```

### Step 3: Test on MQTT

The python program below waits on mqtt topic `/minio` and prints event notifications on the console. We use [paho-mqtt](https://pypi.python.org/pypi/paho-mqtt/) library to do this.

```py
#!/usr/bin/env python3
from __future__ import print_function
import paho.mqtt.client as mqtt

# This is the Subscriber

def on_connect(client, userdata, flags, rc):
  print("Connected with result code "+str(rc))
  # qos level is set to 1
  client.subscribe("minio", 1)

def on_message(client, userdata, msg):
    print(msg.payload)

# client_id is a randomly generated unique ID for the mqtt broker to identify the connection.
client = mqtt.Client(client_id="myclientid",clean_session=False)

client.on_connect = on_connect
client.on_message = on_message

client.connect("localhost",1883,60)
client.loop_forever()
```

Execute this example python program to watch for MQTT events on the console.

```py
python mqtt.py
```

Open another terminal and upload a JPEG image into `images` bucket.

```
mc cp myphoto.jpg myminio/images
```

You should receive the following event notification via MQTT once the upload completes.

```py
python mqtt.py
{“Records”:[{“eventVersion”:”2.0",”eventSource”:”aws:s3",”awsRegion”:”",”eventTime”:”2016–09–08T22:34:38.226Z”,”eventName”:”s3:ObjectCreated:Put”,”userIdentity”:{“principalId”:”minio”},”requestParameters”:{“sourceIPAddress”:”10.1.10.150:44576"},”responseElements”:{},”s3":{“s3SchemaVersion”:”1.0",”configurationId”:”Config”,”bucket”:{“name”:”images”,”ownerIdentity”:{“principalId”:”minio”},”arn”:”arn:aws:s3:::images”},”object”:{“key”:”myphoto.jpg”,”size”:200436,”sequencer”:”147279EAF9F40933"}}}],”level”:”info”,”msg”:””,”time”:”2016–09–08T15:34:38–07:00"}
```

<a name="Elasticsearch"></a>

## Publish MinIO events via Elasticsearch

Install [Elasticsearch](https://www.elastic.co/downloads/elasticsearch) server.

This notification target supports two formats: _namespace_ and _access_.

When the _namespace_ format is used, MinIO synchronizes objects in the bucket with documents in the index. For each event in the MinIO, the server creates a document with the bucket and object name from the event as the document ID. Other details of the event are stored in the body of the document. Thus if an existing object is over-written in MinIO, the corresponding document in the Elasticsearch index is updated. If an object is deleted, the corresponding document is deleted from the index.

When the _access_ format is used, MinIO appends events as documents in an Elasticsearch index. For each event, a document with the event details, with the timestamp of document set to the event's timestamp is appended to an index. The ID of the documented is randomly generated by Elasticsearch. No documents are deleted or modified in this format.

The steps below show how to use this notification target in `namespace` format. The other format is very similar and is omitted for brevity.

### Step 1: Ensure minimum requirements are met

MinIO requires a 5.x series version of Elasticsearch. This is the latest major release series. Elasticsearch provides version upgrade migration guidelines [here](https://www.elastic.co/guide/en/elasticsearch/reference/current/setup-upgrade.html).

### Step 2: Add Elasticsearch endpoint to MinIO

The Elasticsearch configuration is located in the `notify_elasticsearch` key. Create a configuration key-value pair here for your Elasticsearch instance. The key is a name for your Elasticsearch endpoint, and the value is a collection of key-value parameters described in the table below.

```
KEY:
notify_elasticsearch[:name]  publish bucket notifications to Elasticsearch endpoints

ARGS:
url*         (url)                Elasticsearch server's address, with optional authentication info
index*       (string)             Elasticsearch index to store/update events, index is auto-created
format*      (namespace*|access)  'namespace' reflects current bucket/object list and 'access' reflects a journal of object operations, defaults to 'namespace'
queue_dir    (path)               staging dir for undelivered messages e.g. '/home/events'
queue_limit  (number)             maximum limit for undelivered messages, defaults to '100000'
username     (string)             username for Elasticsearch basic-auth
password     (string)             password for Elasticsearch basic-auth
comment      (sentence)           optionally add a comment to this setting
```

or environment variables

```
KEY:
notify_elasticsearch[:name]  publish bucket notifications to Elasticsearch endpoints

ARGS:
MINIO_NOTIFY_ELASTICSEARCH_ENABLE*      (on|off)             enable notify_elasticsearch target, default is 'off'
MINIO_NOTIFY_ELASTICSEARCH_URL*         (url)                Elasticsearch server's address, with optional authentication info
MINIO_NOTIFY_ELASTICSEARCH_INDEX*       (string)             Elasticsearch index to store/update events, index is auto-created
MINIO_NOTIFY_ELASTICSEARCH_FORMAT*      (namespace*|access)  'namespace' reflects current bucket/object list and 'access' reflects a journal of object operations, defaults to 'namespace'
MINIO_NOTIFY_ELASTICSEARCH_QUEUE_DIR    (path)               staging dir for undelivered messages e.g. '/home/events'
MINIO_NOTIFY_ELASTICSEARCH_QUEUE_LIMIT  (number)             maximum limit for undelivered messages, defaults to '100000'
MINIO_NOTIFY_ELASTICSEARCH_USERNAME     (string)             username for Elasticsearch basic-auth
MINIO_NOTIFY_ELASTICSEARCH_PASSWORD     (string)             password for Elasticsearch basic-auth
MINIO_NOTIFY_ELASTICSEARCH_COMMENT      (sentence)           optionally add a comment to this setting
```

For example: `http://localhost:9200` or with authentication info `http://elastic:MagicWord@127.0.0.1:9200`.

MinIO supports persistent event store. The persistent store will backup events when the Elasticsearch broker goes offline and replays it when the broker comes back online. The event store can be configured by setting the directory path in `queue_dir` field and the maximum limit of events in the queue_dir in `queue_limit` field. For eg, the `queue_dir` can be `/home/events` and `queue_limit` can be `1000`. By default, the `queue_limit` is set to 100000.

If Elasticsearch has authentication enabled, the credentials can be supplied to MinIO via the `url` parameter formatted as `PROTO://USERNAME:PASSWORD@ELASTICSEARCH_HOST:PORT`.

To update the configuration, use `mc admin config get` command to get the current configuration.

```sh
$ mc admin config get myminio/ notify_elasticsearch
notify_elasticsearch:1 queue_limit="0"  url="" format="namespace" index="" queue_dir=""
```

Use `mc admin config set` command to update the configuration for the deployment. Restart the MinIO server to put the changes into effect. The server will print a line like `SQS ARNs: arn:minio:sqs::1:elasticsearch` at start-up if there were no errors.

```sh
$ mc admin config set myminio notify_elasticsearch:1 queue_limit="0"  url="http://127.0.0.1:9200" format="namespace" index="minio_events" queue_dir="" username="" password=""
```

Note that, you can add as many Elasticsearch server endpoint configurations as needed by providing an identifier (like "1" in the example above) for the Elasticsearch instance and an object of per-server configuration parameters.

### Step 3: Enable bucket notification using MinIO client

We will now enable bucket event notifications on a bucket named `images`. Whenever a JPEG image is created/overwritten, a new document is added or an existing document is updated in the Elasticsearch index configured above. When an existing object is deleted, the corresponding document is deleted from the index. Thus, the rows in the Elasticsearch index, reflect the `.jpg` objects in the `images` bucket.

To configure this bucket notification, we need the ARN printed by MinIO in the previous step. Additional information about ARN is available [here](http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html).

With the `mc` tool, the configuration is very simple to add. Let us say that the MinIO server is aliased as `myminio` in our mc configuration. Execute the following:

```
mc mb myminio/images
mc event add  myminio/images arn:minio:sqs::1:elasticsearch --suffix .jpg
mc event list myminio/images
arn:minio:sqs::1:elasticsearch s3:ObjectCreated:*,s3:ObjectRemoved:* Filter: suffix=”.jpg”
```

### Step 4: Test on Elasticsearch

Upload a JPEG image into `images` bucket.

```
mc cp myphoto.jpg myminio/images
```

Use curl to view contents of `minio_events` index.

```
$ curl  "http://localhost:9200/minio_events/_search?pretty=true"
{
  "took" : 40,
  "timed_out" : false,
  "_shards" : {
    "total" : 5,
    "successful" : 5,
    "failed" : 0
  },
  "hits" : {
    "total" : 1,
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "minio_events",
        "_type" : "event",
        "_id" : "images/myphoto.jpg",
        "_score" : 1.0,
        "_source" : {
          "Records" : [
            {
              "eventVersion" : "2.0",
              "eventSource" : "minio:s3",
              "awsRegion" : "",
              "eventTime" : "2017-03-30T08:00:41Z",
              "eventName" : "s3:ObjectCreated:Put",
              "userIdentity" : {
                "principalId" : "minio"
              },
              "requestParameters" : {
                "sourceIPAddress" : "127.0.0.1:38062"
              },
              "responseElements" : {
                "x-amz-request-id" : "14B09A09703FC47B",
                "x-minio-origin-endpoint" : "http://192.168.86.115:9000"
              },
              "s3" : {
                "s3SchemaVersion" : "1.0",
                "configurationId" : "Config",
                "bucket" : {
                  "name" : "images",
                  "ownerIdentity" : {
                    "principalId" : "minio"
                  },
                  "arn" : "arn:aws:s3:::images"
                },
                "object" : {
                  "key" : "myphoto.jpg",
                  "size" : 6474,
                  "eTag" : "a3410f4f8788b510d6f19c5067e60a90",
                  "sequencer" : "14B09A09703FC47B"
                }
              },
              "source" : {
                "host" : "127.0.0.1",
                "port" : "38062",
                "userAgent" : "MinIO (linux; amd64) minio-go/2.0.3 mc/2017-02-15T17:57:25Z"
              }
            }
          ]
        }
      }
    ]
  }
}
```

This output shows that a document has been created for the event in Elasticsearch.

Here we see that the document ID is the bucket and object name. In case `access` format was used, the document ID would be automatically generated by Elasticsearch.

<a name="Redis"></a>

## Publish MinIO events via Redis

Install [Redis](http://redis.io/download) server. For illustrative purposes, we have set the database password as "yoursecret".

This notification target supports two formats: _namespace_ and _access_.

When the _namespace_ format is used, MinIO synchronizes objects in the bucket with entries in a hash. For each entry, the key is formatted as "bucketName/objectName" for an object that exists in the bucket, and the value is the JSON-encoded event data about the operation that created/replaced the object in MinIO. When objects are updated or deleted, the corresponding entry in the hash is also updated or deleted.

When the _access_ format is used, MinIO appends events to a list using [RPUSH](https://redis.io/commands/rpush). Each item in the list is a JSON encoded list with two items, where the first item is a timestamp string, and the second item is a JSON object containing event data about the operation that happened in the bucket. No entries appended to the list are updated or deleted by MinIO in this format.

The steps below show how to use this notification target in `namespace` and `access` format.

### Step 1: Add Redis endpoint to MinIO

The MinIO server configuration file is stored on the backend in json format.The Redis configuration is located in the `redis` key under the `notify` top-level key. Create a configuration key-value pair here for your Redis instance. The key is a name for your Redis endpoint, and the value is a collection of key-value parameters described in the table below.

```
KEY:
notify_redis[:name]  publish bucket notifications to Redis datastores

ARGS:
address*     (address)            Redis server's address. For example: `localhost:6379`
key*         (string)             Redis key to store/update events, key is auto-created
format*      (namespace*|access)  'namespace' reflects current bucket/object list and 'access' reflects a journal of object operations, defaults to 'namespace'
password     (string)             Redis server password
queue_dir    (path)               staging dir for undelivered messages e.g. '/home/events'
queue_limit  (number)             maximum limit for undelivered messages, defaults to '100000'
comment      (sentence)           optionally add a comment to this setting
```

or environment variables

```
KEY:
notify_redis[:name]  publish bucket notifications to Redis datastores

ARGS:
MINIO_NOTIFY_REDIS_ENABLE*      (on|off)             enable notify_redis target, default is 'off'
MINIO_NOTIFY_REDIS_KEY*         (string)             Redis key to store/update events, key is auto-created
MINIO_NOTIFY_REDIS_FORMAT*      (namespace*|access)  'namespace' reflects current bucket/object list and 'access' reflects a journal of object operations, defaults to 'namespace'
MINIO_NOTIFY_REDIS_PASSWORD     (string)             Redis server password
MINIO_NOTIFY_REDIS_QUEUE_DIR    (path)               staging dir for undelivered messages e.g. '/home/events'
MINIO_NOTIFY_REDIS_QUEUE_LIMIT  (number)             maximum limit for undelivered messages, defaults to '100000'
MINIO_NOTIFY_REDIS_COMMENT      (sentence)           optionally add a comment to this setting
```

MinIO supports persistent event store. The persistent store will backup events when the Redis broker goes offline and replays it when the broker comes back online. The event store can be configured by setting the directory path in `queue_dir` field and the maximum limit of events in the queue_dir in `queue_limit` field. For eg, the `queue_dir` can be `/home/events` and `queue_limit` can be `1000`. By default, the `queue_limit` is set to 100000.

To update the configuration, use `mc admin config get` command to get the current configuration.

```sh
$ mc admin config get myminio/ notify_redis
notify_redis:1 address="" format="namespace" key="" password="" queue_dir="" queue_limit="0"
```

Use `mc admin config set` command to update the configuration for the deployment.Restart the MinIO server to put the changes into effect. The server will print a line like `SQS ARNs: arn:minio:sqs::1:redis` at start-up if there were no errors.

```sh
$ mc admin config set myminio/ notify_redis:1 address="127.0.0.1:6379" format="namespace" key="bucketevents" password="yoursecret" queue_dir="" queue_limit="0"
```

Note that, you can add as many Redis server endpoint configurations as needed by providing an identifier (like "1" in the example above) for the Redis instance and an object of per-server configuration parameters.

### Step 2: Enable bucket notification using MinIO client

We will now enable bucket event notifications on a bucket named `images`. Whenever a JPEG image is created/overwritten, a new key is added or an existing key is updated in the Redis hash configured above. When an existing object is deleted, the corresponding key is deleted from the Redis hash. Thus, the rows in the Redis hash, reflect the `.jpg` objects in the `images` bucket.

To configure this bucket notification, we need the ARN printed by MinIO in the previous step. Additional information about ARN is available [here](http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html).

With the `mc` tool, the configuration is very simple to add. Let us say that the MinIO server is aliased as `myminio` in our mc configuration. Execute the following:

```
mc mb myminio/images
mc event add myminio/images arn:minio:sqs::1:redis --suffix .jpg
mc event list myminio/images
arn:minio:sqs::1:redis s3:ObjectCreated:*,s3:ObjectRemoved:* Filter: suffix=”.jpg”
```

### Step 3: Test on Redis

Start the `redis-cli` Redis client program to inspect the contents in Redis. Run the `monitor` Redis command. This prints each operation performed on Redis as it occurs.

```
redis-cli -a yoursecret
127.0.0.1:6379> monitor
OK
```

Open another terminal and upload a JPEG image into `images` bucket.

```
mc cp myphoto.jpg myminio/images
```

In the previous terminal, you will now see the operation that MinIO performs on Redis:

```
127.0.0.1:6379> monitor
OK
1490686879.650649 [0 172.17.0.1:44710] "PING"
1490686879.651061 [0 172.17.0.1:44710] "HSET" "minio_events" "images/myphoto.jpg" "{\"Records\":[{\"eventVersion\":\"2.0\",\"eventSource\":\"minio:s3\",\"awsRegion\":\"\",\"eventTime\":\"2017-03-28T07:41:19Z\",\"eventName\":\"s3:ObjectCreated:Put\",\"userIdentity\":{\"principalId\":\"minio\"},\"requestParameters\":{\"sourceIPAddress\":\"127.0.0.1:52234\"},\"responseElements\":{\"x-amz-request-id\":\"14AFFBD1ACE5F632\",\"x-minio-origin-endpoint\":\"http://192.168.86.115:9000\"},\"s3\":{\"s3SchemaVersion\":\"1.0\",\"configurationId\":\"Config\",\"bucket\":{\"name\":\"images\",\"ownerIdentity\":{\"principalId\":\"minio\"},\"arn\":\"arn:aws:s3:::images\"},\"object\":{\"key\":\"myphoto.jpg\",\"size\":2586,\"eTag\":\"5d284463f9da279f060f0ea4d11af098\",\"sequencer\":\"14AFFBD1ACE5F632\"}},\"source\":{\"host\":\"127.0.0.1\",\"port\":\"52234\",\"userAgent\":\"MinIO (linux; amd64) minio-go/2.0.3 mc/2017-02-15T17:57:25Z\"}}]}"
```

Here we see that MinIO performed `HSET` on `minio_events` key.

In case, `access` format was used, then `minio_events` would be a list, and the MinIO server would have performed an `RPUSH` to append to the list. A consumer of this list would ideally use `BLPOP` to remove list items from the left-end of the list.

<a name="NATS"></a>

## Publish MinIO events via NATS

Install NATS from [here](http://nats.io/).

### Step 1: Add NATS endpoint to MinIO

MinIO supports persistent event store. The persistent store will backup events when the NATS broker goes offline and replays it when the broker comes back online. The event store can be configured by setting the directory path in `queue_dir` field and the maximum limit of events in the queue_dir in `queue_limit` field. For eg, the `queue_dir` can be `/home/events` and `queue_limit` can be `1000`. By default, the `queue_limit` is set to 100000.

```
KEY:
notify_nats[:name]  publish bucket notifications to NATS endpoints

ARGS:
address*                          (address)   NATS server address e.g. '0.0.0.0:4222'
subject*                          (string)    NATS subscription subject
username                          (string)    NATS username
password                          (string)    NATS password
token                             (string)    NATS token
tls                               (on|off)    set to 'on' to enable TLS
tls_skip_verify                   (on|off)    trust server TLS without verification, defaults to "on" (verify)
ping_interval                     (duration)  client ping commands interval in s,m,h,d. Disabled by default
streaming                         (on|off)    set to 'on', to use streaming NATS server
streaming_async                   (on|off)    set to 'on', to enable asynchronous publish
streaming_max_pub_acks_in_flight  (number)    number of messages to publish without waiting for ACKs
streaming_cluster_id              (string)    unique ID for NATS streaming cluster
cert_authority                    (string)    path to certificate chain of the target NATS server
client_cert                       (string)    client cert for NATS mTLS auth
client_key                        (string)    client cert key for NATS mTLS auth
queue_dir                         (path)      staging dir for undelivered messages e.g. '/home/events'
queue_limit                       (number)    maximum limit for undelivered messages, defaults to '100000'
comment                           (sentence)  optionally add a comment to this setting
```

or environment variables
```
KEY:
notify_nats[:name]  publish bucket notifications to NATS endpoints

ARGS:
MINIO_NOTIFY_NATS_ENABLE*                           (on|off)    enable notify_nats target, default is 'off'
MINIO_NOTIFY_NATS_ADDRESS*                          (address)   NATS server address e.g. '0.0.0.0:4222'
MINIO_NOTIFY_NATS_SUBJECT*                          (string)    NATS subscription subject
MINIO_NOTIFY_NATS_USERNAME                          (string)    NATS username
MINIO_NOTIFY_NATS_PASSWORD                          (string)    NATS password
MINIO_NOTIFY_NATS_TOKEN                             (string)    NATS token
MINIO_NOTIFY_NATS_TLS                               (on|off)    set to 'on' to enable TLS
MINIO_NOTIFY_NATS_TLS_SKIP_VERIFY                   (on|off)    trust server TLS without verification, defaults to "on" (verify)
MINIO_NOTIFY_NATS_PING_INTERVAL                     (duration)  client ping commands interval in s,m,h,d. Disabled by default
MINIO_NOTIFY_NATS_STREAMING                         (on|off)    set to 'on', to use streaming NATS server
MINIO_NOTIFY_NATS_STREAMING_ASYNC                   (on|off)    set to 'on', to enable asynchronous publish
MINIO_NOTIFY_NATS_STREAMING_MAX_PUB_ACKS_IN_FLIGHT  (number)    number of messages to publish without waiting for ACKs
MINIO_NOTIFY_NATS_STREAMING_CLUSTER_ID              (string)    unique ID for NATS streaming cluster
MINIO_NOTIFY_NATS_CERT_AUTHORITY                    (string)    path to certificate chain of the target NATS server
MINIO_NOTIFY_NATS_CLIENT_CERT                       (string)    client cert for NATS mTLS auth
MINIO_NOTIFY_NATS_CLIENT_KEY                        (string)    client cert key for NATS mTLS auth
MINIO_NOTIFY_NATS_QUEUE_DIR                         (path)      staging dir for undelivered messages e.g. '/home/events'
MINIO_NOTIFY_NATS_QUEUE_LIMIT                       (number)    maximum limit for undelivered messages, defaults to '100000'
MINIO_NOTIFY_NATS_COMMENT                           (sentence)  optionally add a comment to this setting
```

To update the configuration, use `mc admin config get` command to get the current configuration file for the minio deployment.

```sh
$ mc admin config get myminio/ notify_nats
notify_nats:1 password="yoursecret" streaming_max_pub_acks_in_flight="10" subject="" address="0.0.0.0:4222"  token="" username="yourusername" ping_interval="0" queue_limit="0" tls="off" tls_skip_verify="off" streaming_async="on" queue_dir="" streaming_cluster_id="test-cluster" streaming_enable="on"
```

Use `mc admin config set` command to update the configuration for the deployment.Restart MinIO server to reflect config changes. `bucketevents` is the subject used by NATS in this example.

```sh
$ mc admin config set myminio notify_nats:1 password="yoursecret" streaming_max_pub_acks_in_flight="10" subject="" address="0.0.0.0:4222"  token="" username="yourusername" ping_interval="0" queue_limit="0" tls="off" streaming_async="on" queue_dir="" streaming_cluster_id="test-cluster" streaming_enable="on"
```

MinIO server also supports [NATS Streaming mode](http://nats.io/documentation/streaming/nats-streaming-intro/) that offers additional functionality like `At-least-once-delivery`, and `Publisher rate limiting`. To configure MinIO server to send notifications to NATS Streaming server, update the MinIO server configuration file as follows:

Read more about sections `cluster_id`, `client_id` on [NATS documentation](https://github.com/nats-io/nats-streaming-server/blob/master/README.md). Section `maxPubAcksInflight` is explained [here](https://github.com/nats-io/stan.go#publisher-rate-limiting).

### Step 2: Enable bucket notification using MinIO client

We will enable bucket event notification to trigger whenever a JPEG image is uploaded or deleted from `images` bucket on `myminio` server. Here ARN value is `arn:minio:sqs::1:nats`. To understand more about ARN please follow [AWS ARN](http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html) documentation.

```
mc mb myminio/images
mc event add myminio/images arn:minio:sqs::1:nats --suffix .jpg
mc event list myminio/images
arn:minio:sqs::1:nats s3:ObjectCreated:*,s3:ObjectRemoved:* Filter: suffix=”.jpg”
```

### Step 3: Test on NATS

If you use NATS server, check out this sample program below to log the bucket notification added to NATS.

```go
package main

// Import Go and NATS packages
import (
	"log"
	"runtime"

	"github.com/nats-io/nats.go"
)

func main() {

	// Create server connection
	natsConnection, _ := nats.Connect("nats://yourusername:yoursecret@localhost:4222")
	log.Println("Connected")

	// Subscribe to subject
	log.Printf("Subscribing to subject 'bucketevents'\n")
	natsConnection.Subscribe("bucketevents", func(msg *nats.Msg) {

		// Handle the message
		log.Printf("Received message '%s\n", string(msg.Data)+"'")
	})

	// Keep the connection alive
	runtime.Goexit()
}
```

```
go run nats.go
2016/10/12 06:39:18 Connected
2016/10/12 06:39:18 Subscribing to subject 'bucketevents'
```

Open another terminal and upload a JPEG image into `images` bucket.

```
mc cp myphoto.jpg myminio/images
```

The example `nats.go` program prints event notification to console.

```
go run nats.go
2016/10/12 06:51:26 Connected
2016/10/12 06:51:26 Subscribing to subject 'bucketevents'
2016/10/12 06:51:33 Received message '{"EventType":"s3:ObjectCreated:Put","Key":"images/myphoto.jpg","Records":[{"eventVersion":"2.0","eventSource":"aws:s3","awsRegion":"","eventTime":"2016-10-12T13:51:33Z","eventName":"s3:ObjectCreated:Put","userIdentity":{"principalId":"minio"},"requestParameters":{"sourceIPAddress":"[::1]:57106"},"responseElements":{},"s3":{"s3SchemaVersion":"1.0","configurationId":"Config","bucket":{"name":"images","ownerIdentity":{"principalId":"minio"},"arn":"arn:aws:s3:::images"},"object":{"key":"myphoto.jpg","size":56060,"eTag":"1d97bf45ecb37f7a7b699418070df08f","sequencer":"147CCD1AE054BFD0"}}}],"level":"info","msg":"","time":"2016-10-12T06:51:33-07:00"}
```

If you use NATS Streaming server, check out this sample program below to log the bucket notification added to NATS.

```go
package main

// Import Go and NATS packages
import (
	"fmt"
	"runtime"

	"github.com/nats-io/stan.go"
)

func main() {

	var stanConnection stan.Conn

	subscribe := func() {
		fmt.Printf("Subscribing to subject 'bucketevents'\n")
		stanConnection.Subscribe("bucketevents", func(m *stan.Msg) {

			// Handle the message
			fmt.Printf("Received a message: %s\n", string(m.Data))
		})
	}


	stanConnection, _ = stan.Connect("test-cluster", "test-client", stan.NatsURL("nats://yourusername:yoursecret@0.0.0.0:4222"), stan.SetConnectionLostHandler(func(c stan.Conn, _ error) {
		go func() {
			for {
				// Reconnect if the connection is lost.
				if stanConnection == nil || stanConnection.NatsConn() == nil ||  !stanConnection.NatsConn().IsConnected() {
					stanConnection, _ = stan.Connect("test-cluster", "test-client", stan.NatsURL("nats://yourusername:yoursecret@0.0.0.0:4222"), stan.SetConnectionLostHandler(func(c stan.Conn, _ error) {
						if c.NatsConn() != nil {
							c.NatsConn().Close()
						}
						_ = c.Close()
					}))
					if stanConnection != nil {
						subscribe()
					}

				}
			}

		}()
	}))

	// Subscribe to subject
	subscribe()

	// Keep the connection alive
	runtime.Goexit()
}

```

```
go run nats.go
2017/07/07 11:47:40 Connected
2017/07/07 11:47:40 Subscribing to subject 'bucketevents'
```

Open another terminal and upload a JPEG image into `images` bucket.

```
mc cp myphoto.jpg myminio/images
```

The example `nats.go` program prints event notification to console.

```
Received a message: {"EventType":"s3:ObjectCreated:Put","Key":"images/myphoto.jpg","Records":[{"eventVersion":"2.0","eventSource":"minio:s3","awsRegion":"","eventTime":"2017-07-07T18:46:37Z","eventName":"s3:ObjectCreated:Put","userIdentity":{"principalId":"minio"},"requestParameters":{"sourceIPAddress":"192.168.1.80:55328"},"responseElements":{"x-amz-request-id":"14CF20BD1EFD5B93","x-minio-origin-endpoint":"http://127.0.0.1:9000"},"s3":{"s3SchemaVersion":"1.0","configurationId":"Config","bucket":{"name":"images","ownerIdentity":{"principalId":"minio"},"arn":"arn:aws:s3:::images"},"object":{"key":"myphoto.jpg","size":248682,"eTag":"f1671feacb8bbf7b0397c6e9364e8c92","contentType":"image/jpeg","userDefined":{"content-type":"image/jpeg"},"versionId":"1","sequencer":"14CF20BD1EFD5B93"}},"source":{"host":"192.168.1.80","port":"55328","userAgent":"MinIO (linux; amd64) minio-go/2.0.4 mc/DEVELOPMENT.GOGET"}}],"level":"info","msg":"","time":"2017-07-07T11:46:37-07:00"}
```

<a name="PostgreSQL"></a>

## Publish MinIO events via PostgreSQL

> NOTE: Until release RELEASE.2020-04-10T03-34-42Z PostgreSQL notification used to support following options:
>
> ```
> host                (hostname)           Postgres server hostname (used only if `connection_string` is empty)
> port                (port)               Postgres server port, defaults to `5432` (used only if `connection_string` is empty)
> username            (string)             database username (used only if `connection_string` is empty)
> password            (string)             database password (used only if `connection_string` is empty)
> database            (string)             database name (used only if `connection_string` is empty)
> ```
>
> These are now deprecated, if you plan to upgrade to any releases after *RELEASE.2020-04-10T03-34-42Z* make sure
> to migrate to only using *connection_string* option. To migrate, once you have upgraded all the servers use the
> following command to update the existing notification targets.
>
> ```
> mc admin config set myminio/ notify_postgres[:name] connection_string="host=hostname port=2832 username=psqluser password=psqlpass database=bucketevents"
> ```
>
> Please make sure this step is carried out, without this step PostgreSQL notification targets will not work,
> an error message will be shown on the console upon server upgrade/restart, make sure to follow the above
> instructions appropriately. For further questions please join our https://slack.min.io

Install [PostgreSQL](https://www.postgresql.org/) database server. For illustrative purposes, we have set the "postgres" user password as `password` and created a database called `minio_events` to store the events.

This notification target supports two formats: _namespace_ and _access_.

When the _namespace_ format is used, MinIO synchronizes objects in the bucket with rows in the table. It creates rows with two columns: key and value. The key is the bucket and object name of an object that exists in MinIO. The value is JSON encoded event data about the operation that created/replaced the object in MinIO. When objects are updated or deleted, the corresponding row from this table is updated or deleted respectively.

When the _access_ format is used, MinIO appends events to a table. It creates rows with two columns: event_time and event_data. The event_time is the time at which the event occurred in the MinIO server. The event_data is the JSON encoded event data about the operation on an object. No rows are deleted or modified in this format.

The steps below show how to use this notification target in `namespace` format. The other format is very similar and is omitted for brevity.

### Step 1: Ensure minimum requirements are met

MinIO requires PostgreSQL version 9.5 or above. MinIO uses the [`INSERT ON CONFLICT`](https://www.postgresql.org/docs/9.5/static/sql-insert.html#SQL-ON-CONFLICT) (aka UPSERT) feature, introduced in version 9.5 and the [JSONB](https://www.postgresql.org/docs/9.4/static/datatype-json.html) data-type introduced in version 9.4.

### Step 2: Add PostgreSQL endpoint to MinIO

The PostgreSQL configuration is located in the `notify_postgresql` key. Create a configuration key-value pair here for your PostgreSQL instance. The key is a name for your PostgreSQL endpoint, and the value is a collection of key-value parameters described in the table below.

```
KEY:
notify_postgres[:name]  publish bucket notifications to Postgres databases

ARGS:
connection_string*   (string)             Postgres server connection-string e.g. "host=localhost port=5432 dbname=minio_events user=postgres password=password sslmode=disable"
table*               (string)             DB table name to store/update events, table is auto-created
format*              (namespace*|access)  'namespace' reflects current bucket/object list and 'access' reflects a journal of object operations, defaults to 'namespace'
queue_dir            (path)               staging dir for undelivered messages e.g. '/home/events'
queue_limit          (number)             maximum limit for undelivered messages, defaults to '100000'
max_open_connections (number)             maximum number of open connections to the database, defaults to '2'
comment              (sentence)           optionally add a comment to this setting
```

or environment variables
```
KEY:
notify_postgres[:name]  publish bucket notifications to Postgres databases

ARGS:
MINIO_NOTIFY_POSTGRES_ENABLE*              (on|off)             enable notify_postgres target, default is 'off'
MINIO_NOTIFY_POSTGRES_CONNECTION_STRING*   (string)             Postgres server connection-string e.g. "host=localhost port=5432 dbname=minio_events user=postgres password=password sslmode=disable"
MINIO_NOTIFY_POSTGRES_TABLE*               (string)             DB table name to store/update events, table is auto-created
MINIO_NOTIFY_POSTGRES_FORMAT*              (namespace*|access)  'namespace' reflects current bucket/object list and 'access' reflects a journal of object operations, defaults to 'namespace'
MINIO_NOTIFY_POSTGRES_QUEUE_DIR            (path)               staging dir for undelivered messages e.g. '/home/events'
MINIO_NOTIFY_POSTGRES_QUEUE_LIMIT          (number)             maximum limit for undelivered messages, defaults to '100000'
MINIO_NOTIFY_POSTGRES_COMMENT              (sentence)           optionally add a comment to this setting
MINIO_NOTIFY_POSTGRES_MAX_OPEN_CONNECTIONS (number)             maximum number of open connections to the database, defaults to '2'
```

> NOTE: If the `max_open_connections` key or the environment variable `MINIO_NOTIFY_POSTGRES_MAX_OPEN_CONNECTIONS` is set to `0`, There will be no limit set on the number of
> open connections to the database. This setting is generally NOT recommended as the behavior may be inconsistent during recursive deletes in `namespace` format.

MinIO supports persistent event store. The persistent store will backup events when the PostgreSQL connection goes offline and replays it when the broker comes back online. The event store can be configured by setting the directory path in `queue_dir` field and the maximum limit of events in the queue_dir in `queue_limit` field. For eg, the `queue_dir` can be `/home/events` and `queue_limit` can be `1000`. By default, the `queue_limit` is set to 100000.

Note that for illustration here, we have disabled SSL. In the interest of security, for production this is not recommended.
To update the configuration, use `mc admin config get` command to get the current configuration.

```sh
$ mc admin config get myminio notify_postgres
notify_postgres:1 queue_dir="" connection_string="" queue_limit="0"  table="" format="namespace"
```

Use `mc admin config set` command to update the configuration for the deployment. Restart the MinIO server to put the changes into effect. The server will print a line like `SQS ARNs: arn:minio:sqs::1:postgresql` at start-up if there were no errors.

```sh
$ mc admin config set myminio notify_postgres:1 connection_string="host=localhost port=5432 dbname=minio_events user=postgres password=password sslmode=disable" table="bucketevents" format="namespace"
```

Note that, you can add as many PostgreSQL server endpoint configurations as needed by providing an identifier (like "1" in the example above) for the PostgreSQL instance and an object of per-server configuration parameters.

### Step 3: Enable bucket notification using MinIO client

We will now enable bucket event notifications on a bucket named `images`. Whenever a JPEG image is created/overwritten, a new row is added or an existing row is updated in the PostgreSQL configured above. When an existing object is deleted, the corresponding row is deleted from the PostgreSQL table. Thus, the rows in the PostgreSQL table, reflect the `.jpg` objects in the `images` bucket.

To configure this bucket notification, we need the ARN printed by MinIO in the previous step. Additional information about ARN is available [here](http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html).

With the `mc` tool, the configuration is very simple to add. Let us say that the MinIO server is aliased as `myminio` in our mc configuration. Execute the following:

```
# Create bucket named `images` in myminio
mc mb myminio/images
# Add notification configuration on the `images` bucket using the MySQL ARN. The --suffix argument filters events.
mc event add myminio/images arn:minio:sqs::1:postgresql --suffix .jpg
# Print out the notification configuration on the `images` bucket.
mc event list myminio/images
mc event list myminio/images
arn:minio:sqs::1:postgresql s3:ObjectCreated:*,s3:ObjectRemoved:* Filter: suffix=”.jpg”
```

### Step 4: Test on PostgreSQL

Open another terminal and upload a JPEG image into `images` bucket.

```
mc cp myphoto.jpg myminio/images
```

Open PostgreSQL terminal to list the rows in the `bucketevents` table.

```
$ psql -h 127.0.0.1 -U postgres -d minio_events
minio_events=# select * from bucketevents;

key                 |                      value
--------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 images/myphoto.jpg | {"Records": [{"s3": {"bucket": {"arn": "arn:aws:s3:::images", "name": "images", "ownerIdentity": {"principalId": "minio"}}, "object": {"key": "myphoto.jpg", "eTag": "1d97bf45ecb37f7a7b699418070df08f", "size": 56060, "sequencer": "147CE57C70B31931"}, "configurationId": "Config", "s3SchemaVersion": "1.0"}, "awsRegion": "", "eventName": "s3:ObjectCreated:Put", "eventTime": "2016-10-12T21:18:20Z", "eventSource": "aws:s3", "eventVersion": "2.0", "userIdentity": {"principalId": "minio"}, "responseElements": {}, "requestParameters": {"sourceIPAddress": "[::1]:39706"}}]}
(1 row)
```

<a name="MySQL"></a>

## Publish MinIO events via MySQL

> NOTE: Until release RELEASE.2020-04-10T03-34-42Z MySQL notification used to support following options:
>
> ```
> host         (hostname)           MySQL server hostname (used only if `dsn_string` is empty)
> port         (port)               MySQL server port (used only if `dsn_string` is empty)
> username     (string)             database username (used only if `dsn_string` is empty)
> password     (string)             database password (used only if `dsn_string` is empty)
> database     (string)             database name (used only if `dsn_string` is empty)
> ```
>
> These are now deprecated, if you plan to upgrade to any releases after *RELEASE.2020-04-10T03-34-42Z* make sure
> to migrate to only using *dsn_string* option. To migrate, once you have upgraded all the servers use the
> following command to update the existing notification targets.
>
> ```
> mc admin config set myminio/ notify_mysql[:name] dsn_string="mysqluser:mysqlpass@tcp(localhost:2832)/bucketevents"
> ```
>
> Please make sure this step is carried out, without this step MySQL notification targets will not work,
> an error message will be shown on the console upon server upgrade/restart, make sure to follow the above
> instructions appropriately. For further questions please join our https://slack.min.io

Install MySQL from [here](https://dev.mysql.com/downloads/mysql/). For illustrative purposes, we have set the root password as `password` and created a database called `miniodb` to store the events.

This notification target supports two formats: _namespace_ and _access_.

When the _namespace_ format is used, MinIO synchronizes objects in the bucket with rows in the table. It creates rows with two columns: key_name and value. The key_name is the bucket and object name of an object that exists in MinIO. The value is JSON encoded event data about the operation that created/replaced the object in MinIO. When objects are updated or deleted, the corresponding row from this table is updated or deleted respectively.

When the _access_ format is used, MinIO appends events to a table. It creates rows with two columns: event_time and event_data. The event_time is the time at which the event occurred in the MinIO server. The event_data is the JSON encoded event data about the operation on an object. No rows are deleted or modified in this format.

The steps below show how to use this notification target in `namespace` format. The other format is very similar and is omitted for brevity.

### Step 1: Ensure minimum requirements are met

MinIO requires MySQL version 5.7.8 or above. MinIO uses the [JSON](https://dev.mysql.com/doc/refman/5.7/en/json.html) data-type introduced in version 5.7.8. We tested this setup on MySQL 5.7.17.

### Step 2: Add MySQL server endpoint configuration to MinIO

The MySQL configuration is located in the `notify_mysql` key. Create a configuration key-value pair here for your MySQL instance. The key is a name for your MySQL endpoint, and the value is a collection of key-value parameters described in the table below.

```
KEY:
notify_mysql[:name]  publish bucket notifications to MySQL databases. When multiple MySQL server endpoints are needed, a user specified "name" can be added for each configuration, (e.g."notify_mysql:myinstance").

ARGS:
dsn_string*          (string)             MySQL data-source-name connection string e.g. "<user>:<password>@tcp(<host>:<port>)/<database>"
table*               (string)             DB table name to store/update events, table is auto-created
format*              (namespace*|access)  'namespace' reflects current bucket/object list and 'access' reflects a journal of object operations, defaults to 'namespace'
queue_dir            (path)               staging dir for undelivered messages e.g. '/home/events'
queue_limit          (number)             maximum limit for undelivered messages, defaults to '100000'
max_open_connections (number)             maximum number of open connections to the database, defaults to '2'
comment              (sentence)           optionally add a comment to this setting
```

or environment variables
```
KEY:
notify_mysql[:name]  publish bucket notifications to MySQL databases

ARGS:
MINIO_NOTIFY_MYSQL_ENABLE*              (on|off)             enable notify_mysql target, default is 'off'
MINIO_NOTIFY_MYSQL_DSN_STRING*          (string)             MySQL data-source-name connection string e.g. "<user>:<password>@tcp(<host>:<port>)/<database>"
MINIO_NOTIFY_MYSQL_TABLE*               (string)             DB table name to store/update events, table is auto-created
MINIO_NOTIFY_MYSQL_FORMAT*              (namespace*|access)  'namespace' reflects current bucket/object list and 'access' reflects a journal of object operations, defaults to 'namespace'
MINIO_NOTIFY_MYSQL_QUEUE_DIR            (path)               staging dir for undelivered messages e.g. '/home/events'
MINIO_NOTIFY_MYSQL_QUEUE_LIMIT          (number)             maximum limit for undelivered messages, defaults to '100000'
MINIO_NOTIFY_MYSQL_MAX_OPEN_CONNECTIONS (number)             maximum number of open connections to the database, defaults to '2'
MINIO_NOTIFY_MYSQL_COMMENT              (sentence)           optionally add a comment to this setting
```

> NOTE: If the `max_open_connections` key or the environment variable `MINIO_NOTIFY_MYSQL_MAX_OPEN_CONNECTIONS` is set to `0`, There will be no limit set on the number of
> open connections to the database. This setting is generally NOT recommended as the behavior may be inconsistent during recursive deletes in `namespace` format.

`dsn_string` is required and is of form `"<user>:<password>@tcp(<host>:<port>)/<database>"`

MinIO supports persistent event store. The persistent store will backup events if MySQL connection goes offline and then replays the stored events when the broken connection comes back up. The event store can be configured by setting a directory path in `queue_dir` field, and the maximum number of events, which can be stored in a `queue_dir`, in `queue_limit` field. For example, `queue_dir` can be set to `/home/events` and `queue_limit` can be set to `1000`. By default, the `queue_limit` is set to `100000`.

Before updating the configuration, let's start with `mc admin config get` command to get the current configuration.

```sh
$ mc admin config get myminio/ notify_mysql
notify_mysql:myinstance enable=off format=namespace host= port= username= password= database= dsn_string= table= queue_dir= queue_limit=0
```

Use `mc admin config set` command to update MySQL notification configuration for the deployment with `dsn_string` parameter:

```sh
$ mc admin config set myminio notify_mysql:myinstance table="minio_images" dsn_string="root:xxxx@tcp(172.17.0.1:3306)/miniodb"
```

Note that, you can add as many MySQL server endpoint configurations as needed by providing an identifier (like "myinstance" in the example above) for each MySQL instance desired.

Restart the MinIO server to put the changes into effect. The server will print a line like `SQS ARNs: arn:minio:sqs::myinstance:mysql` at start-up, if there are no errors.

### Step 3: Enable bucket notification using MinIO client

We will now setup bucket notifications on a bucket named `images`. Whenever a JPEG image object is created/overwritten, a new row is added or an existing row is updated in the MySQL table configured above. When an existing object is deleted, the corresponding row is deleted from the MySQL table. Thus, the rows in the MySQL table, reflect the `.jpg` objects in the `images` bucket.

To configure this bucket notification, we need the ARN printed by MinIO in the previous step. Additional information about ARN is available [here](http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html).

With the `mc` tool, the configuration is very simple to add. Let us say that the MinIO server is aliased as `myminio` in our mc configuration. Execute the following:

```
# Create bucket named `images` in myminio
mc mb myminio/images
# Add notification configuration on the `images` bucket using the MySQL ARN. The --suffix argument filters events.
mc event add myminio/images arn:minio:sqs::myinstance:mysql --suffix .jpg
# Print out the notification configuration on the `images` bucket.
mc event list myminio/images
arn:minio:sqs::myinstance:mysql s3:ObjectCreated:*,s3:ObjectRemoved:*,s3:ObjectAccessed:* Filter: suffix=”.jpg”
```

### Step 4: Test on MySQL

Open another terminal and upload a JPEG image into `images` bucket:

```
mc cp myphoto.jpg myminio/images
```

Open MySQL terminal and list the rows in the `minio_images` table.

```
$ mysql -h 172.17.0.1 -P 3306 -u root -p miniodb
mysql> select * from minio_images;
+--------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| key_name           | value                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
+--------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| images/myphoto.jpg | {"Records": [{"s3": {"bucket": {"arn": "arn:aws:s3:::images", "name": "images", "ownerIdentity": {"principalId": "minio"}}, "object": {"key": "myphoto.jpg", "eTag": "467886be95c8ecfd71a2900e3f461b4f", "size": 26, "sequencer": "14AC59476F809FD3"}, "configurationId": "Config", "s3SchemaVersion": "1.0"}, "awsRegion": "", "eventName": "s3:ObjectCreated:Put", "eventTime": "2017-03-16T11:29:00Z", "eventSource": "aws:s3", "eventVersion": "2.0", "userIdentity": {"principalId": "minio"}, "responseElements": {"x-amz-request-id": "14AC59476F809FD3", "x-minio-origin-endpoint": "http://192.168.86.110:9000"}, "requestParameters": {"sourceIPAddress": "127.0.0.1:38260"}}]} |
+--------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)

```

<a name="apache-kafka"></a>

## Publish MinIO events via Kafka

Install Apache Kafka from [here](http://kafka.apache.org/).

### Step 1: Ensure minimum requirements are met

MinIO requires Kafka version 0.10 or 0.9. Internally MinIO uses the [Shopify/sarama](https://github.com/Shopify/sarama/) library and so has the same version compatibility as provided by this library.

### Step 2: Add Kafka endpoint to MinIO

MinIO supports persistent event store. The persistent store will backup events when the kafka broker goes offline and replays it when the broker comes back online. The event store can be configured by setting the directory path in `queue_dir` field and the maximum limit of events in the queue_dir in `queue_limit` field. For eg, the `queue_dir` can be `/home/events` and `queue_limit` can be `1000`. By default, the `queue_limit` is set to 100000.

```
KEY:
notify_kafka[:name]  publish bucket notifications to Kafka endpoints

ARGS:
brokers*         (csv)       comma separated list of Kafka broker addresses
topic            (string)    Kafka topic used for bucket notifications
sasl_username    (string)    username for SASL/PLAIN or SASL/SCRAM authentication
sasl_password    (string)    password for SASL/PLAIN or SASL/SCRAM authentication
sasl_mechanism   (string)    sasl authentication mechanism, default 'PLAIN'
tls_client_auth  (string)    clientAuth determines the Kafka server's policy for TLS client auth
sasl             (on|off)    set to 'on' to enable SASL authentication
tls              (on|off)    set to 'on' to enable TLS
tls_skip_verify  (on|off)    trust server TLS without verification, defaults to "on" (verify)
client_tls_cert  (path)      path to client certificate for mTLS auth
client_tls_key   (path)      path to client key for mTLS auth
queue_dir        (path)      staging dir for undelivered messages e.g. '/home/events'
queue_limit      (number)    maximum limit for undelivered messages, defaults to '100000'
version          (string)    specify the version of the Kafka cluster e.g '2.2.0'
comment          (sentence)  optionally add a comment to this setting
```

or environment variables
```
KEY:
notify_kafka[:name]  publish bucket notifications to Kafka endpoints

ARGS:
MINIO_NOTIFY_KAFKA_ENABLE*          (on|off)                enable notify_kafka target, default is 'off'
MINIO_NOTIFY_KAFKA_BROKERS*         (csv)                   comma separated list of Kafka broker addresses
MINIO_NOTIFY_KAFKA_TOPIC            (string)                Kafka topic used for bucket notifications
MINIO_NOTIFY_KAFKA_SASL_USERNAME    (string)                username for SASL/PLAIN or SASL/SCRAM authentication
MINIO_NOTIFY_KAFKA_SASL_PASSWORD    (string)                password for SASL/PLAIN or SASL/SCRAM authentication
MINIO_NOTIFY_KAFKA_SASL_MECHANISM   (plain*|sha256|sha512)  sasl authentication mechanism, default 'plain'
MINIO_NOTIFY_KAFKA_TLS_CLIENT_AUTH  (string)                clientAuth determines the Kafka server's policy for TLS client auth
MINIO_NOTIFY_KAFKA_SASL             (on|off)                set to 'on' to enable SASL authentication
MINIO_NOTIFY_KAFKA_TLS              (on|off)                set to 'on' to enable TLS
MINIO_NOTIFY_KAFKA_TLS_SKIP_VERIFY  (on|off)                trust server TLS without verification, defaults to "on" (verify)
MINIO_NOTIFY_KAFKA_CLIENT_TLS_CERT  (path)                  path to client certificate for mTLS auth
MINIO_NOTIFY_KAFKA_CLIENT_TLS_KEY   (path)                  path to client key for mTLS auth
MINIO_NOTIFY_KAFKA_QUEUE_DIR        (path)                  staging dir for undelivered messages e.g. '/home/events'
MINIO_NOTIFY_KAFKA_QUEUE_LIMIT      (number)                maximum limit for undelivered messages, defaults to '100000'
MINIO_NOTIFY_KAFKA_COMMENT          (sentence)              optionally add a comment to this setting
MINIO_NOTIFY_KAFKA_VERSION          (string)                specify the version of the Kafka cluster e.g. '2.2.0'
```

To update the configuration, use `mc admin config get` command to get the current configuration.

```sh
$ mc admin config get myminio/ notify_kafka
notify_kafka:1 tls_skip_verify="off"  queue_dir="" queue_limit="0" sasl="off" sasl_password="" sasl_username="" tls_client_auth="0" tls="off" brokers="" topic="" client_tls_cert="" client_tls_key="" version=""
```

Use `mc admin config set` command to update the configuration for the deployment. Restart the MinIO server to put the changes into effect. The server will print a line like `SQS ARNs: arn:minio:sqs::1:kafka` at start-up if there were no errors.`bucketevents` is the topic used by kafka in this example.

```sh
$ mc admin config set myminio notify_kafka:1 tls_skip_verify="off"  queue_dir="" queue_limit="0" sasl="off" sasl_password="" sasl_username="" tls_client_auth="0" tls="off" client_tls_cert="" client_tls_key="" brokers="localhost:9092,localhost:9093" topic="bucketevents" version=""
```

### Step 3: Enable bucket notification using MinIO client

We will enable bucket event notification to trigger whenever a JPEG image is uploaded or deleted from `images` bucket on `myminio` server. Here ARN value is `arn:minio:sqs::1:kafka`. To understand more about ARN please follow [AWS ARN](http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html) documentation.

```
mc mb myminio/images
mc event add  myminio/images arn:minio:sqs::1:kafka --suffix .jpg
mc event list myminio/images
arn:minio:sqs::1:kafka s3:ObjectCreated:*,s3:ObjectRemoved:* Filter: suffix=”.jpg”
```

### Step 4: Test on Kafka

We used [kafkacat](https://github.com/edenhill/kafkacat) to print all notifications on the console.

```
kafkacat -C -b localhost:9092 -t bucketevents
```

Open another terminal and upload a JPEG image into `images` bucket.

```
mc cp myphoto.jpg myminio/images
```

`kafkacat` prints the event notification to the console.

```
kafkacat -b localhost:9092 -t bucketevents
{
    "EventName": "s3:ObjectCreated:Put",
    "Key": "images/myphoto.jpg",
    "Records": [
        {
            "eventVersion": "2.0",
            "eventSource": "minio:s3",
            "awsRegion": "",
            "eventTime": "2019-09-10T17:41:54Z",
            "eventName": "s3:ObjectCreated:Put",
            "userIdentity": {
                "principalId": "AKIAIOSFODNN7EXAMPLE"
            },
            "requestParameters": {
                "accessKey": "AKIAIOSFODNN7EXAMPLE",
                "region": "",
                "sourceIPAddress": "192.168.56.192"
            },
            "responseElements": {
                "x-amz-request-id": "15C3249451E12784",
                "x-minio-deployment-id": "751a8ba6-acb2-42f6-a297-4cdf1cf1fa4f",
                "x-minio-origin-endpoint": "http://192.168.97.83:9000"
            },
            "s3": {
                "s3SchemaVersion": "1.0",
                "configurationId": "Config",
                "bucket": {
                    "name": "images",
                    "ownerIdentity": {
                        "principalId": "AKIAIOSFODNN7EXAMPLE"
                    },
                    "arn": "arn:aws:s3:::images"
                },
                "object": {
                    "key": "myphoto.jpg",
                    "size": 6474,
                    "eTag": "430f89010c77aa34fc8760696da62d08-1",
                    "contentType": "image/jpeg",
                    "userMetadata": {
                        "content-type": "image/jpeg"
                    },
                    "versionId": "1",
                    "sequencer": "15C32494527B46C5"
                }
            },
            "source": {
                "host": "192.168.56.192",
                "port": "",
                "userAgent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:69.0) Gecko/20100101 Firefox/69.0"
            }
        }
    ]
}
```

<a name="webhooks"></a>

## Publish MinIO events via Webhooks

[Webhooks](https://en.wikipedia.org/wiki/Webhook) are a way to receive information when it happens, rather than continually polling for that data.

### Step 1: Add Webhook endpoint to MinIO

MinIO supports persistent event store. The persistent store will backup events when the webhook goes offline and replays it when the broker comes back online. The event store can be configured by setting the directory path in `queue_dir` field and the maximum limit of events in the queue_dir in `queue_limit` field. For eg, the `queue_dir` can be `/home/events` and `queue_limit` can be `1000`. By default, the `queue_limit` is set to 100000.

```
KEY:
notify_webhook[:name]  publish bucket notifications to webhook endpoints

ARGS:
endpoint*    (url)       webhook server endpoint e.g. http://localhost:8080/minio/events
auth_token   (string)    opaque string or JWT authorization token
queue_dir    (path)      staging dir for undelivered messages e.g. '/home/events'
queue_limit  (number)    maximum limit for undelivered messages, defaults to '100000'
client_cert  (string)    client cert for Webhook mTLS auth
client_key   (string)    client cert key for Webhook mTLS auth
comment      (sentence)  optionally add a comment to this setting
```

or environment variables
```
KEY:
notify_webhook[:name]  publish bucket notifications to webhook endpoints

ARGS:
MINIO_NOTIFY_WEBHOOK_ENABLE*      (on|off)    enable notify_webhook target, default is 'off'
MINIO_NOTIFY_WEBHOOK_ENDPOINT*    (url)       webhook server endpoint e.g. http://localhost:8080/minio/events
MINIO_NOTIFY_WEBHOOK_AUTH_TOKEN   (string)    opaque string or JWT authorization token
MINIO_NOTIFY_WEBHOOK_QUEUE_DIR    (path)      staging dir for undelivered messages e.g. '/home/events'
MINIO_NOTIFY_WEBHOOK_QUEUE_LIMIT  (number)    maximum limit for undelivered messages, defaults to '100000'
MINIO_NOTIFY_WEBHOOK_COMMENT      (sentence)  optionally add a comment to this setting
MINIO_NOTIFY_WEBHOOK_CLIENT_CERT  (string)    client cert for Webhook mTLS auth
MINIO_NOTIFY_WEBHOOK_CLIENT_KEY   (string)    client cert key for Webhook mTLS auth   
```

```sh
$ mc admin config get myminio/ notify_webhook
notify_webhook:1 endpoint="" auth_token="" queue_limit="0" queue_dir="" client_cert="" client_key=""
```

Use `mc admin config set` command to update the configuration for the deployment. Here the endpoint is the server listening for webhook notifications. Save the settings and restart the MinIO server for changes to take effect. Note that the endpoint needs to be live and reachable when you restart your MinIO server.

```sh
$ mc admin config set myminio notify_webhook:1 queue_limit="0"  endpoint="http://localhost:3000" queue_dir=""
```

### Step 2: Enable bucket notification using MinIO client

We will enable bucket event notification to trigger whenever a JPEG image is uploaded to `images` bucket on `myminio` server. Here ARN value is `arn:minio:sqs::1:webhook`. To learn more about ARN please follow [AWS ARN](http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html) documentation.

```
mc mb myminio/images
mc mb myminio/images-thumbnail
mc event add myminio/images arn:minio:sqs::1:webhook --event put --suffix .jpg
```

Check if event notification is successfully configured by

```
mc event list myminio/images
```

You should get a response like this

```
arn:minio:sqs::1:webhook   s3:ObjectCreated:*   Filter: suffix=".jpg"
```

### Step 3: Test with Thumbnailer

We used [Thumbnailer](https://github.com/minio/thumbnailer) to listen for MinIO notifications when a new JPEG file is uploaded (HTTP PUT). Triggered by a notification, Thumbnailer uploads a thumbnail of new image to MinIO server. To start with, download and install Thumbnailer.

```
git clone https://github.com/minio/thumbnailer/
npm install
```

Then open the Thumbnailer config file at `config/webhook.json` and add the configuration for your MinIO server and then start Thumbnailer by

```
NODE_ENV=webhook node thumbnail-webhook.js
```

Thumbnailer starts running at `http://localhost:3000/`. Next, configure the MinIO server to send notifications to this URL (as mentioned in step 1) and use `mc` to set up bucket notifications (as mentioned in step 2). Then upload a JPEG image to MinIO server by

```
mc cp ~/images.jpg myminio/images
.../images.jpg:  8.31 KB / 8.31 KB ┃▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓┃ 100.00% 59.42 KB/s 0s
```

Wait a few moments, then check the bucket’s contents with mc ls — you will see a thumbnail appear.

```
mc ls myminio/images-thumbnail
[2017-02-08 11:39:40 IST]   992B images-thumbnail.jpg
```

<a name="NSQ"></a>

## Publish MinIO events to NSQ

Install an NSQ Daemon from [here](https://nsq.io/). Or use the following Docker
command for starting an nsq daemon:

```
docker run --rm -p 4150-4151:4150-4151 nsqio/nsq /nsqd
```

### Step 1: Add NSQ endpoint to MinIO

MinIO supports persistent event store. The persistent store will backup events when the NSQ broker goes offline and replays it when the broker comes back online. The event store can be configured by setting the directory path in `queue_dir` field and the maximum limit of events in the queue_dir in `queue_limit` field. For eg, the `queue_dir` can be `/home/events` and `queue_limit` can be `1000`. By default, the `queue_limit` is set to 100000.

To update the configuration, use `mc admin config get` command to get the current configuration for `notify_nsq`.

```
KEY:
notify_nsq[:name]  publish bucket notifications to NSQ endpoints

ARGS:
nsqd_address*    (address)   NSQ server address e.g. '127.0.0.1:4150'
topic*           (string)    NSQ topic
tls              (on|off)    set to 'on' to enable TLS
tls_skip_verify  (on|off)    trust server TLS without verification, defaults to "on" (verify)
queue_dir        (path)      staging dir for undelivered messages e.g. '/home/events'
queue_limit      (number)    maximum limit for undelivered messages, defaults to '100000'
comment          (sentence)  optionally add a comment to this setting
```

or environment variables
```
KEY:
notify_nsq[:name]  publish bucket notifications to NSQ endpoints

ARGS:
MINIO_NOTIFY_NSQ_ENABLE*          (on|off)    enable notify_nsq target, default is 'off'
MINIO_NOTIFY_NSQ_NSQD_ADDRESS*    (address)   NSQ server address e.g. '127.0.0.1:4150'
MINIO_NOTIFY_NSQ_TOPIC*           (string)    NSQ topic
MINIO_NOTIFY_NSQ_TLS              (on|off)    set to 'on' to enable TLS
MINIO_NOTIFY_NSQ_TLS_SKIP_VERIFY  (on|off)    trust server TLS without verification, defaults to "on" (verify)
MINIO_NOTIFY_NSQ_QUEUE_DIR        (path)      staging dir for undelivered messages e.g. '/home/events'
MINIO_NOTIFY_NSQ_QUEUE_LIMIT      (number)    maximum limit for undelivered messages, defaults to '100000'
MINIO_NOTIFY_NSQ_COMMENT          (sentence)  optionally add a comment to this setting
```

```sh
$ mc admin config get myminio/ notify_nsq
notify_nsq:1 nsqd_address="" queue_dir="" queue_limit="0"  tls="off" tls_skip_verify="off" topic=""
```

Use `mc admin config set` command to update the configuration for the deployment. Restart the MinIO server to put the changes into effect. The server will print a line like `SQS ARNs: arn:minio:sqs::1:nsq` at start-up if there were no errors.

```sh
$ mc admin config set myminio notify_nsq:1 nsqd_address="127.0.0.1:4150" queue_dir="" queue_limit="0" tls="off" tls_skip_verify="on" topic="minio"
```

Note that, you can add as many NSQ daemon endpoint configurations as needed by providing an identifier (like "1" in the example above) for the NSQ instance and an object of per-server configuration parameters.

### Step 2: Enable bucket notification using MinIO client

We will enable bucket event notification to trigger whenever a JPEG image is uploaded or deleted `images` bucket on `myminio` server. Here ARN value is `arn:minio:sqs::1:nsq`.

```
mc mb myminio/images
mc event add  myminio/images arn:minio:sqs::1:nsq --suffix .jpg
mc event list myminio/images
arn:minio:sqs::1:nsq s3:ObjectCreated:*,s3:ObjectRemoved:* Filter: suffix=”.jpg”
```

### Step 3: Test on NSQ

The simplest test is to download `nsq_tail` from [nsq github](https://github.com/nsqio/nsq/releases)

```
./nsq_tail -nsqd-tcp-address 127.0.0.1:4150 -topic minio
```

Open another terminal and upload a JPEG image into `images` bucket.

```
mc cp gopher.jpg myminio/images
```

You should receive the following event notification via NSQ once the upload completes.

```
{"EventName":"s3:ObjectCreated:Put","Key":"images/gopher.jpg","Records":[{"eventVersion":"2.0","eventSource":"minio:s3","awsRegion":"","eventTime":"2018-10-31T09:31:11Z","eventName":"s3:ObjectCreated:Put","userIdentity":{"principalId":"21EJ9HYV110O8NVX2VMS"},"requestParameters":{"sourceIPAddress":"10.1.1.1"},"responseElements":{"x-amz-request-id":"1562A792DAA53426","x-minio-origin-endpoint":"http://10.0.3.1:9000"},"s3":{"s3SchemaVersion":"1.0","configurationId":"Config","bucket":{"name":"images","ownerIdentity":{"principalId":"21EJ9HYV110O8NVX2VMS"},"arn":"arn:aws:s3:::images"},"object":{"key":"gopher.jpg","size":162023,"eTag":"5337769ffa594e742408ad3f30713cd7","contentType":"image/jpeg","userMetadata":{"content-type":"image/jpeg"},"versionId":"1","sequencer":"1562A792DAA53426"}},"source":{"host":"","port":"","userAgent":"MinIO (linux; amd64) minio-go/v6.0.8 mc/DEVELOPMENT.GOGET"}}]}
```