github.com/Jeffail/benthos/v3@v3.65.0/website/docs/components/outputs/drop_on.md (about) 1 --- 2 title: drop_on 3 type: output 4 status: stable 5 categories: ["Utility"] 6 --- 7 8 <!-- 9 THIS FILE IS AUTOGENERATED! 10 11 To make changes please edit the contents of: 12 lib/output/drop_on.go 13 --> 14 15 import Tabs from '@theme/Tabs'; 16 import TabItem from '@theme/TabItem'; 17 18 19 Attempts to write messages to a child output and if the write fails for one of a list of configurable reasons the message is dropped instead of being reattempted. 20 21 ```yaml 22 # Config fields, showing default values 23 output: 24 label: "" 25 drop_on: 26 error: false 27 back_pressure: "" 28 output: {} 29 ``` 30 31 Regular Benthos outputs will apply back pressure when downstream services aren't accessible, and Benthos retries (or nacks) all messages that fail to be delivered. However, in some circumstances, or for certain output types, we instead might want to relax these mechanisms, which is when this output becomes useful. 32 33 ## Fields 34 35 ### `error` 36 37 Whether messages should be dropped when the child output returns an error. For example, this could be when an http_client output gets a 4XX response code. 38 39 40 Type: `bool` 41 Default: `false` 42 43 ### `back_pressure` 44 45 An optional duration string that determines the maximum length of time to wait for a given message to be accepted by the child output before the message should be dropped instead. The most common reason for an output to block is when waiting for a lost connection to be re-established. Once a message has been dropped due to back pressure all subsequent messages are dropped immediately until the output is ready to process them again. Note that if `error` is set to `false` and this field is specified then messages dropped due to back pressure will return an error response. 46 47 48 Type: `string` 49 Default: `""` 50 51 ```yaml 52 # Examples 53 54 back_pressure: 30s 55 56 back_pressure: 1m 57 ``` 58 59 ### `output` 60 61 A child output. 62 63 64 Type: `output` 65 Default: `{}` 66 67 ## Examples 68 69 <Tabs defaultValue="Dropping failed HTTP requests" values={[ 70 { label: 'Dropping failed HTTP requests', value: 'Dropping failed HTTP requests', }, 71 { label: 'Dropping from outputs that cannot connect', value: 'Dropping from outputs that cannot connect', }, 72 ]}> 73 74 <TabItem value="Dropping failed HTTP requests"> 75 76 In this example we have a fan_out broker, where we guarantee delivery to our Kafka output, but drop messages if they fail our secondary HTTP client output. 77 78 ```yaml 79 output: 80 broker: 81 pattern: fan_out 82 outputs: 83 - kafka: 84 addresses: [ foobar:6379 ] 85 topic: foo 86 - drop_on: 87 error: true 88 output: 89 http_client: 90 url: http://example.com/foo/messages 91 verb: POST 92 ``` 93 94 </TabItem> 95 <TabItem value="Dropping from outputs that cannot connect"> 96 97 Most outputs that attempt to establish and long-lived connection will apply back-pressure when the connection is lost. The following example has a websocket output where if it takes longer than 10 seconds to establish a connection, or recover a lost one, pending messages are dropped. 98 99 ```yaml 100 output: 101 drop_on: 102 back_pressure: 10s 103 output: 104 websocket: 105 url: ws://example.com/foo/messages 106 ``` 107 108 </TabItem> 109 </Tabs> 110 111