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switch

The switch output type allows you to route messages to different outputs based on their contents.

# Common config fields, showing default values
output:
label: ""
switch:
retry_until_success: true
cases: []

Messages must successfully route to one or more outputs, otherwise this is considered an error and the message is reprocessed. In order to explicitly drop messages that do not match your cases add one final case with a drop output.

Examples

The most common use for a switch output is to multiplex messages across a range of output destinations. The following config checks the contents of the field type of messages and sends foo type messages to an amqp_1 output, bar type messages to a gcp_pubsub output, and everything else to a redis_streams output.

Outputs can have their own processors associated with them, and in this example the redis_streams output has a processor that enforces the presence of a type field before sending it.

output:
switch:
cases:
- check: this.type == "foo"
output:
amqp_1:
url: amqps://guest:guest@localhost:5672/
target_address: queue:/the_foos
- check: this.type == "bar"
output:
gcp_pubsub:
project: dealing_with_mike
topic: mikes_bars
- output:
redis_streams:
url: tcp://localhost:6379
stream: everything_else
processors:
- bloblang: |
root = this
root.type = this.type | "unknown"

Fields

retry_until_success

If a selected output fails to send a message this field determines whether it is reattempted indefinitely. If set to false the error is instead propagated back to the input level.

If a message can be routed to >1 outputs it is usually best to set this to true in order to avoid duplicate messages being routed to an output.

Type: bool
Default: true

strict_mode

This field determines whether an error should be reported if no condition is met. If set to true, an error is propagated back to the input level. The default behavior is false, which will drop the message.

Type: bool
Default: false

max_in_flight

The maximum number of parallel message batches to have in flight at any given time. Note that if a child output has a higher max_in_flight then the switch output will automatically match it, therefore this value is the minimum max_in_flight to set in cases where the child values can't be inferred (such as when using resource outputs as children).

Type: int
Default: 1

cases

A list of switch cases, outlining outputs that can be routed to.

Type: array
Default: []

# Examples
cases:
- check: this.urls.contains("http://benthos.dev")
continue: true
output:
cache:
key: ${!json("id")}
target: foo
- output:
s3:
bucket: bar
path: ${!json("id")}

cases[].check

A Bloblang query that should return a boolean value indicating whether a message should be routed to the case output. If left empty the case always passes.

Type: string
Default: ""

# Examples
check: this.type == "foo"
check: this.contents.urls.contains("https://benthos.dev/")

cases[].output

An output for messages that pass the check to be routed to.

Type: output
Default: {}

cases[].continue

Indicates whether, if this case passes for a message, the next case should also be tested.

Type: bool
Default: false