[pkg/ottl] Set method should allow dynamically setting map values to attributes

[rupeshnemade]

Is your feature request related to a problem? Please describe.

While using transform processor, we tried setting set kubernetes labels to a single attribute 'labels' in a body as below.

But Set method doesn't iterate through the map of values & instead needs all keys in array to be explicitly mentioned like below-
set(attributes["kubernetes.labels"], resource.attributes["pod_labels_app"])

Kubernetes labels is something dynamic things & we can't explicitly mention label name in OTEL processor rules.

Describe the solution you'd like

Set method in here should allow iterate through the map & fetch all values so that we can perform something like this-

set(attributes["kubernetes.labels"], resource.attributes["pod_labels_*"])

Describe alternatives you've considered

No response

Additional context

No response

[TylerHelmuth]

I can think of two ways to handle this situation:

1. Update all contexts used by the transform processor to understand that wildcard (*) in a key means "all fields in a map that match that key".
2. Create a new Factory Function that knows how to take a map and a string pattern and returns a map that contains all the fields from the input map that match the pattern. It would behave similarly to replace_all_patterns.

I would opt for the second because I like the flexibility that Factory Functions provide. I prefer putting business logic in the function vs the contexts.

@bogdandrutu @kentquirk @evan-bradley what do you think?

[evan-bradley]

I agree, I think a function would be better for this sort of operation. In addition to keeping business logic out of the contexts I think it also provides a good pattern for doing other types of matching (regex, filtering, etc.), and makes it more explicit what is going on.

[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.

Pinging code owners:

• processor/transform: @TylerHelmuth @kentquirk @bogdandrutu @evan-bradley
• pkg/ottl: @TylerHelmuth @kentquirk @bogdandrutu @evan-bradley

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

[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.

Pinging code owners:

• processor/transform: @TylerHelmuth @kentquirk @bogdandrutu @evan-bradley
• pkg/ottl: @TylerHelmuth @kentquirk @bogdandrutu @evan-bradley

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