Feature Request: Add Namespace Filtering Support to `k8sobserver` Extension

[Ygshvr]

Component(s)

extension/observer/k8sobserver

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

The k8sobserver extension in the OpenTelemetry Collector's receiver_creator is really useful in discovering Kubernetes resources such as pods, services, ingresses, and nodes. However, it currently lacks a built-in mechanism to filter these resources by namespace. Implementing namespace filtering would significantly enhance the flexibility and scalability of Kubernetes monitoring, especially in multi-tenant or large-scale environments.

Describe the solution you'd like

Introduce a namespaces configuration option within the k8sobserver extension. This would allow users to specify an array of namespaces to watch.
Example configuration

extensions:
  k8s_observer:
    auth_type: serviceAccount
    namespaces: [default, prod, staging]
    observe_pods: true
    observe_services: true
    observe_ingresses: true
    observe_nodes: false

receivers:
  receiver_creator:
    watch_observers: [k8s_observer]
    receivers:
      redis:
        rule: type == "port" && pod.name matches "redis"
        config:
          password: '`pod.labels["SECRET"]`'

Describe alternatives you've considered

No response

Additional context

No response

[github-actions]

Pinging code owners:

• extension/observer/k8sobserver: @dmitryax @ChrsMark

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[ChrsMark]

Thank's @Ygshvr, scoping based on k8s Namespace makes sense!

My suggestion would be to ensure consistency with other components like k8sclusterreceiver where the setting already exists and is a single string: https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/v0.124.1/receiver/k8sclusterreceiver/config.go#L46

[bacherfl]

@ChrsMark If this issue is available, I would like to work on this

[Ygshvr]

Thanks @ChrsMark for the suggestion, but my proposal was based on k8seventsreceiver and k8sobjectreceiver where it's a list. This is useful in case one has to watch multiple namespaces.

[ChrsMark]

Thanks @ChrsMark for the suggestion, but my proposal was based on k8seventsreceiver and k8sobjectreceiver where it's a list. This is useful in case one has to watch multiple namespaces.

That's interesting, I would expect those to be aligned since all fetch data from the k8s API (on cluster level).

@TylerHelmuth @dmitryax do you by any chance recall why those differ? Shouldn't we have a common pattern?