[k8sattributesprocessor] Support set resource attributes from environment variables of k8s pods

[chenlujjj]

Component(s)

processor/k8sattributes

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

We are using the receiver creator with prometheus simple receiver as the receiver inside to automatically discover pods with prometheus.io/scrape: "true" annotations and collect metrics from them. The problem is that the service.name labels in the metrics are prometheus_simple/<ip:port>, but we want them be the real service name of the applications.

Describe the solution you'd like

Currently the k8sattributesprocessor can set resource attributes from k8s labels and annotations of pods, namespaces and nodes. If it can also extract pod environment variables, such as the OTEL_RESOURCE_ATTRIBUTES, OTEL_SERVICE_NAME, and set them as the resource attributes, that would help to solve the problem above.

Describe alternatives you've considered

No response

Additional context

No response

[github-actions]

Pinging code owners:

• processor/k8sattributes: @dmitryax @rmfitzpatrick @fatsheep9146 @TylerHelmuth

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[TylerHelmuth]

Is prometheus_simple from prometheus_simple/<ip:port> the service name? If so, extracting the value from the resource attribute via the transformprocessor is a better way to go. https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/pkg/ottl/ottlfuncs#extractpatterns

[chenlujjj]

Hi @TylerHelmuth , metrics service.name label is set as prometheus_simple/<ip:port> by the prometheus_simple receiver. The logic should be at this line of code.

So I came up with the idea to use k8sattributesprocessor to set the service.name from pod environment variable. Say if the pod has an environment variable OTEL_SERVICE_NAME=foo or OTEL_RESOURCE_ATTRIBUTES=service.name=foo, then the service.name label will be set as foo