Allow to specify resource label as 'from_attribute' in routingprocessor

[maxsivkov]

Is your feature request related to a problem? Please describe.
No

Describe the solution you'd like
Currently from_attribute can reference http header only. Allowing to specify resource label (from the ResourceSpansSlice struct) as from_attribute allows to route traces based on attributes gathered earlier. For example to route trace to specific exporter based on a pod name (gathered by k8sprocessor)

Describe alternatives you've considered
Cannot find out any

Additional context
Each resource should be processed individually based on a resource's attribute value.
In this case batching will not work.
may be we need to introduce additional parameter like attribute_source with values FromHeader and FromResource.

Currently I am studying opentelemetry, so I may be wrong with terminology.
with 'resource attributes' I mean attribute from the following map
https://github.com/open-telemetry/opentelemetry-collector/blob/c71f5bbe77492603f52a19a857d5db3de3bce2d3/consumer/pdata/generated_resource.go#L47

[pmalek-sumo]

@maxsivkov 👋

Haven't #5694 and #5869 covered what you've described above?

[github-actions]

This issue has been inactive for 60 days. It will be closed in 60 days if there is no activity. To ping code owners by adding a component label, see Adding Labels via Comments, or if you are unsure of which component this issue relates to, please ping @open-telemetry/collector-contrib-triagers. If this issue is still relevant, please ping the code owners or leave a comment explaining why it is still relevant. Otherwise, please close it.

[kovrus]

@maxsivkov The routing processor is able to do that with both conventional configuration and OTTL statements, see Readme.

@jpkrohling can you please close the issue?

[vchirikov]

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

Logs:

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

@kovrus / @jpkrohling looks like OTTL in routing doesn't work without from_attribute, isn't it?
How can I achieve something like this?
p.s. otel/opentelemetry-collector-contrib:0.66.0 version

---

upd: created a new issue for this