[processor/routing] OTTL statements doesn't work without from_attribute

[vchirikov]

Component(s)

processor/routing

What happened?

Description

According to the docs
We should be able to use OTTL statements without from_attribute and other "conventional routing items"

opentelemetry-collector-contrib/processor/routingprocessor/README.md

Lines 66 to 85 in fa262b4

	```yaml
	processors:
	routing:
	default_exporters:
	- jaeger
	table:
	- statement: route() where resource.attributes["X-Tenant"] == "acme"
	exporters: [jaeger/acme]
	- statement: delete_key(resource.attributes, "X-Tenant") where IsMatch(resource.attributes["X-Tenant"], ".*corp") == true
	exporters: [jaeger/ecorp]
	exporters:
	jaeger:
	endpoint: localhost:14250
	jaeger/acme:
	endpoint: localhost:24250
	jaeger/ecorp:
	endpoint: localhost:34250
	```

But if I try to use it without from_attribute the collector won't start.

p.s. and it will be useful to add an example of filtering k8s logs for example into 2 elasticsearchexporters based on OTTL, because it's unclear how to not route to all exporters in case of similar attributes (for example how to route only one container from the pod into exporter)

Collector version

0.66.0

Environment information

Environment

Docker image otel/opentelemetry-collector-contrib:0.66.0

OpenTelemetry Collector configuration

processors:
  routing:
    default_exporters: [elasticsearch/default]
    table:
      - statement: route() where (resource.attributes["k8s.namespace.name"] == "infra" and resource.attributes["k8s.container.name"] != "access-logs") or resource.attributes["k8s.namespace.name"] == "flux-system"
        exporters: [elasticsearch/infra]
      - statement: route() where resource.attributes["k8s.namespace.name"] == "infra" and resource.attributes["k8s.container.name"] == "access-logs"
        exporters: [elasticsearch/ingress]
      - statement: route() where resource.attributes["k8s.namespace.name"] == "staging" and resource.attributes["k8s.container.name"] == "app"
        exporters: [elasticsearch/apps]

Log output

Error: invalid configuration: processor "routing" has invalid configuration: invalid attribute to read the route's value from: the FromAttribute property is empty
2022-11-30 13:55:57.699034 I | collector server run finished with error: invalid configuration: processor "routing" has invalid configuration: invalid attribute to read the route's value from: the FromAttribute property is empty

Additional context

#3746 looks like similar

[github-actions]

Pinging code owners:

• processor/routing: @jpkrohling @kovrus

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[jpkrohling]

@kovrus, are you able to handle this one?

[vchirikov]

I checked with 2 otel collectors, with config like this:

  receivers:
    jaeger: null
    otlp:
      protocols:
        grpc:
          endpoint: 0.0.0.0:4317
        http: null
    prometheus: null
    zipkin: null

  processors:
    batch: {}
    memory_limiter: null
    routing:
      from_attribute: service.name
      default_exporters: [logging]
      table:
        - statement: route() where resource.attributes["service.name"] == "123"
          exporters: [otlp]

  exporters:
    logging:
      verbosity: detailed
      sampling_initial: 1000
      sampling_thereafter: 2000
    otlp:
      endpoint: otel-2:4317
      tls:
        insecure: true
        insecure_skip_verify: true
  service:
    extensions:
      - health_check
    pipelines:
      logs:
        receivers:
          - otlp
        processors:  []
        exporters:
          - logging
      metrics: null
      traces:
        receivers:
          - otlp
        processors:
          - routing
        exporters:
          - otlp
          - logging

and all traces were in logging exporter:

2022-12-01T16:22:56.741Z	info	ResourceSpans #0
Resource SchemaURL: 
Resource attributes:
+     -> service.name: Str(123)
     -> service.instance.id: Str(5464a388-9ee0-4c63-b858-3d910597adba)
     -> k8s.pod.ip: Str(127.0.0.1)
ScopeSpans #0
ScopeSpans SchemaURL: 
InstrumentationScope opentelemetry 1.0.0
Span #0
    Trace ID       : e6b6b12325d04a35c368ae67b629bece
    Parent ID      : 
    ID             : 4c8c253d2b3f97f3
    Name           : Parent_01
    Kind           : Internal
    Start time     : 2022-12-01 16:22:56.7316525 +0000 UTC
    End time       : 2022-12-01 16:22:56.7316554 +0000 UTC
    Status code    : Unset
    Status message : 
	{"kind": "exporter", "data_type": "traces", "name": "logging"}

Please check the config, because seems like the OTTL feature doesn't work at all in routing processor

upd:

Well, I found out that that OTTL doesn't work without these settings:

      from_attribute: __ # required to start processor, could be anything
      attribute_source: resource # statements on a resource don't work without this

[kovrus]

@jpkrohling please assign it to me