Suggestion to allow for conditional ingestor outputs

[jblackman]

Logstash allows us to wrap an output (or input) in a condition block. Could I propose adding a condition: key to the logstash_parser.outputs array? For example:

instance_groups:
- name: ingestor
  jobs:
  - name: ingestor_syslog
    properties:
      logstash_parser:
        outputs:
        - plugin: foo
          options:
            key: "value"
          condition:  '[syslog_program] == "gorouter"'

and this would produce output config like:

outputs {
  if [syslog_program] == "gorouter" {
    foo {
      key => "value"
    }
  }
}

Happy to create a PR for this. I just want to get some feedback if this is an appropriate way to make the change. An alternative would be to create a output_overrides parameter to allow complete customisability, similar to filter_overrides.

[jblackman]

It could also be extended to else blocks with a minor change:

outputs:
- plugin: foo
  options:
    key: "value"
  condition:  'if [syslog_program] == "gorouter"'
- plugin: bar
  options:
    key: "value"
  condition:  'else'

which would produce:

outputs {
  if [syslog_program] == "gorouter" {
    foo {
      key => "value"
    }
  }
  else {
    bar {
      key => "value"
    }
  }
}