github.com/Jeffail/benthos/v3@v3.65.0/website/docs/components/outputs/mqtt.md

---
title: mqtt
type: output
status: stable
categories: ["Services"]
---

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     THIS FILE IS AUTOGENERATED!

     To make changes please edit the contents of:
     lib/output/mqtt.go
-->

import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';


Pushes messages to an MQTT broker.


<Tabs defaultValue="common" values={[
  { label: 'Common', value: 'common', },
  { label: 'Advanced', value: 'advanced', },
]}>

<TabItem value="common">

```yaml
# Common config fields, showing default values
output:
  label: ""
  mqtt:
    urls:
      - tcp://localhost:1883
    topic: benthos_topic
    client_id: benthos_output
    qos: 1
    connect_timeout: 30s
    write_timeout: 3s
    retained: false
    max_in_flight: 1
```

</TabItem>
<TabItem value="advanced">

```yaml
# All config fields, showing default values
output:
  label: ""
  mqtt:
    urls:
      - tcp://localhost:1883
    topic: benthos_topic
    client_id: benthos_output
    dynamic_client_id_suffix: ""
    qos: 1
    connect_timeout: 30s
    write_timeout: 3s
    retained: false
    retained_interpolated: ""
    will:
      enabled: false
      qos: 0
      retained: false
      topic: ""
      payload: ""
    user: ""
    password: ""
    keepalive: 30
    tls:
      enabled: false
      skip_cert_verify: false
      enable_renegotiation: false
      root_cas: ""
      root_cas_file: ""
      client_certs: []
    max_in_flight: 1
```

</TabItem>
</Tabs>

The `topic` field can be dynamically set using function interpolations
described [here](/docs/configuration/interpolation#bloblang-queries). When sending batched
messages these interpolations are performed per message part.

## Performance

This output benefits from sending multiple messages in flight in parallel for
improved performance. You can tune the max number of in flight messages with the
field `max_in_flight`.

## Fields

### `urls`

A list of URLs to connect to. If an item of the list contains commas it will be expanded into multiple URLs.


Type: `array`  
Default: `["tcp://localhost:1883"]`  

```yaml
# Examples

urls:
  - tcp://localhost:1883
```

### `topic`

The topic to publish messages to.


Type: `string`  
Default: `"benthos_topic"`  

### `client_id`

An identifier for the client connection.


Type: `string`  
Default: `"benthos_output"`  

### `dynamic_client_id_suffix`

Append a dynamically generated suffix to the specified `client_id` on each run of the pipeline. This can be useful when clustering Benthos producers.


Type: `string`  
Default: `""`  

| Option | Summary |
|---|---|
| `nanoid` | append a nanoid of length 21 characters |


### `qos`

The QoS value to set for each message.


Type: `int`  
Default: `1`  
Options: `0`, `1`, `2`.

### `connect_timeout`

The maximum amount of time to wait in order to establish a connection before the attempt is abandoned.


Type: `string`  
Default: `"30s"`  
Requires version 3.58.0 or newer  

```yaml
# Examples

connect_timeout: 1s

connect_timeout: 500ms
```

### `write_timeout`

The maximum amount of time to wait to write data before the attempt is abandoned.


Type: `string`  
Default: `"3s"`  
Requires version 3.58.0 or newer  

```yaml
# Examples

write_timeout: 1s

write_timeout: 500ms
```

### `retained`

Set message as retained on the topic.


Type: `bool`  
Default: `false`  

### `retained_interpolated`

Override the value of `retained` with an interpolable value, this allows it to be dynamically set based on message contents. The value must resolve to either `true` or `false`.
This field supports [interpolation functions](/docs/configuration/interpolation#bloblang-queries).


Type: `string`  
Default: `""`  
Requires version 3.59.0 or newer  

### `will`

Set last will message in case of Benthos failure


Type: `object`  

### `will.enabled`

Whether to enable last will messages.


Type: `bool`  
Default: `false`  

### `will.qos`

Set QoS for last will message.


Type: `int`  
Default: `0`  
Options: `0`, `1`, `2`.

### `will.retained`

Set retained for last will message.


Type: `bool`  
Default: `false`  

### `will.topic`

Set topic for last will message.


Type: `string`  
Default: `""`  

### `will.payload`

Set payload for last will message.


Type: `string`  
Default: `""`  

### `user`

A username to connect with.


Type: `string`  
Default: `""`  

### `password`

A password to connect with.


Type: `string`  
Default: `""`  

### `keepalive`

Max seconds of inactivity before a keepalive message is sent.


Type: `int`  
Default: `30`  

### `tls`

Custom TLS settings can be used to override system defaults.


Type: `object`  
Requires version 3.45.0 or newer  

### `tls.enabled`

Whether custom TLS settings are enabled.


Type: `bool`  
Default: `false`  

### `tls.skip_cert_verify`

Whether to skip server side certificate verification.


Type: `bool`  
Default: `false`  

### `tls.enable_renegotiation`

Whether to allow the remote server to repeatedly request renegotiation. Enable this option if you're seeing the error message `local error: tls: no renegotiation`.


Type: `bool`  
Default: `false`  
Requires version 3.45.0 or newer  

### `tls.root_cas`

An optional root certificate authority to use. This is a string, representing a certificate chain from the parent trusted root certificate, to possible intermediate signing certificates, to the host certificate.


Type: `string`  
Default: `""`  

```yaml
# Examples

root_cas: |-
  -----BEGIN CERTIFICATE-----
  ...
  -----END CERTIFICATE-----
```

### `tls.root_cas_file`

An optional path of a root certificate authority file to use. This is a file, often with a .pem extension, containing a certificate chain from the parent trusted root certificate, to possible intermediate signing certificates, to the host certificate.


Type: `string`  
Default: `""`  

```yaml
# Examples

root_cas_file: ./root_cas.pem
```

### `tls.client_certs`

A list of client certificates to use. For each certificate either the fields `cert` and `key`, or `cert_file` and `key_file` should be specified, but not both.


Type: `array`  
Default: `[]`  

```yaml
# Examples

client_certs:
  - cert: foo
    key: bar

client_certs:
  - cert_file: ./example.pem
    key_file: ./example.key
```

### `tls.client_certs[].cert`

A plain text certificate to use.


Type: `string`  
Default: `""`  

### `tls.client_certs[].key`

A plain text certificate key to use.


Type: `string`  
Default: `""`  

### `tls.client_certs[].cert_file`

The path to a certificate to use.


Type: `string`  
Default: `""`  

### `tls.client_certs[].key_file`

The path of a certificate key to use.


Type: `string`  
Default: `""`  

### `max_in_flight`

The maximum number of messages to have in flight at a given time. Increase this to improve throughput.


Type: `int`  
Default: `1`