Add if/then/else support to processors

[andrewkroh]

This allows for a condition to be used with a list of processors and for a list of
processors to be executed if the condition does not match.

This is a contrived example that adds fields and tags to the event if true, otherwise it drops the event.

processors: [
  {
    "if": {
      "and": [
        {
          "equals.type": "login"
        },
        {
          "range.uid.lt": 500
        }
      ]
    },
    "then": [
      {
        "add_fields": {
          "target": "",
          "fields": {
            "uid_type": "reserved"
          }
        }
      },
      {
        "add_tags": {
          "tags": [
            "reserved_user_login"
          ]
        }
      }
    ],
    "else": {
      "drop_event": null
    }
  }
]

[ph]

@andrewkroh Excellent works I have added a few comments, feel free to consider them or not, maybe the only things to look is the case of the NIL inside the THEN branch and the tests for multiple levels of IF.

The case for multiple if, It should work but it wont be pretty in the YAML :)

[ph]

Thanks for adding this, I see that we do a nil check for the else branch, but looking at the code the then branch could be also nil.

[andrewkroh]

When the config is Unpacked the then field is is validated via validate:"required". This prevents it from ever being nil.

[ph]

Looking at the comment maybe Processors or List might be a better name?

[andrewkroh]

I didn't want to change it because it's public and used in multiple places in the code. But I agree the name isn't that great.

[ph]

oh yeah its public :(

[ph]

This will only count the top level processors and not the processors defined inside a If/Else/branch?

[andrewkroh]

It should log information about all of the processors, even nested ones. But since there are multiple calls to New you will see a few of these debug statements when using if/then/else. The last one being the complete processor tree.

=== RUN   TestIfElseThenProcessor/if-then-else-if
2019-02-14T10:04:42.904-0500	DEBUG	[conditions]	conditions/conditions.go:95	New condition range: map[uid:{<nil> <nil> <nil> 0xc0000a6dc0}]
2019-02-14T10:04:42.904-0500	DEBUG	[processors]	processors/processor.go:88	Generated new processors: add_fields={"uid_type":"reserved"}
2019-02-14T10:04:42.904-0500	DEBUG	[conditions]	conditions/conditions.go:95	New condition equals: map[uid:{500  false}]
2019-02-14T10:04:42.904-0500	DEBUG	[processors]	processors/processor.go:88	Generated new processors: add_fields={"uid_type":"eq_500"}
2019-02-14T10:04:42.904-0500	DEBUG	[processors]	processors/processor.go:88	Generated new processors: add_fields={"uid_type":"gt_500"}
2019-02-14T10:04:42.904-0500	DEBUG	[processors]	processors/processor.go:88	Generated new processors: if equals: map[uid:{500  false}] then add_fields={"uid_type":"eq_500"} else add_fields={"uid_type":"gt_500"}
2019-02-14T10:04:42.904-0500	DEBUG	[processors]	processors/processor.go:88	Generated new processors: if range: map[uid:{<nil> <nil> <nil> 0xc0000a6dc0}] then add_fields={"uid_type":"reserved"} else if equals: map[uid:{500  false}] then add_fields={"uid_type":"eq_500"} else add_fields={"uid_type":"gt_500"}

[andrewkroh]

@ph I updated the code with new test case for nesting and replied. This is ready for another look.

[ph]

@andrewkroh code LGTM, I will restart the jenkins job.. its a timeout for fetching golang.

[ph]

Jenkins test this please

[andrewkroh]

Jenkins is green. Travis is mostly green; just a metricbeat consul integration test failed.