Try

Executes a list of child processors on messages only if no prior processors have failed (or the errors have been cleared).

# Config fields, showing default values
label: ""
try: []

This processor behaves similarly to the for_each processor, where a list of child processors are applied to individual messages of a batch. However, if a message has failed any prior processor (before or during the try block) then that message will skip all following processors.

For example, with the following config:

pipeline:
  processors:
    - resource: foo
    - try:
      - resource: bar
      - resource: baz
      - resource: buz

If the processor bar fails for a particular message, that message will skip the processors baz and buz. Similarly, if bar succeeds but baz does not then buz will be skipped. If the processor foo fails for a message then none of bar, baz or buz are executed on that message.

This processor is useful for when child processors depend on the successful output of previous processors. This processor can be followed with a catch processor for defining child processors to be applied only to failed messages.

More information about error handing can be found here.

Nesting within a catch block

In some cases it might be useful to nest a try block within a catch block, since the catch processor only clears errors after executing its child processors. This means a nested try processor will not execute unless the errors are explicitly cleared beforehand.

This can be done by inserting an empty catch block before the try block like as follows:

pipeline:
  processors:
    - resource: foo
    - catch:
      - log:
          level: ERROR
          message: "Foo failed due to: ${! error() }"
      - catch: [] # Clear prior error
      - try:
        - resource: bar
        - resource: baz