Test rerouting works for input packages (and normal integrations) that provide type: metrics

[gsantoro]

As a follow up of this comment and this issue, we would like to test if rerouting is enabled (it has the correct permissions) for a sample input package prometheus_input. No code changes should be required. Similar test has been done before for input packages with type: logs, so this is just to test that it behaves similarly for type: metrics data sets.

[gsantoro]

make sure the testing is done against Kubernetes from source since 8.9.0-SNAPSHOT today doesn't have the code changes made in fleet to support dynamic_dataset/namespace

[gsantoro]

I have done some testing with the following setup:

1. Elastic-package to setup stack with 8.9.0-SNAPSHOT
2. Stop kibana container and start Kibana from source
3. Setup elastic-agent running in k8s with Fleet and connect with the elastic-package network
4. setup a sample pod exporting prometheus-like metrics so that you can have an endpoint reachable by the prometheus integration
5. add prometheus integration to the agent policy
6. once everything is setup. you can check if there is an entry for metrics-*-* in one of the elastic-agent api keys.

[gsantoro]

I can confirm that metrics-*-* is correctly added to the permissions of the API for an agent with an input package for metrics. Here I have used the Prometheus input integration for testing.

Since this integration Prometheus Input is currently in Technical preview it can only be found when enabling Display beta integrations in Kibana in the list of integrations

[gsantoro]

i can also confirm that the same behaviour is valid for non input packages (aka normal integrations).

I temporarily created a 1.5.1 version of prometheus with the code changes in the manifest

# Ensures agents have permissions to write data to `logs-*-*`
elasticsearch.dynamic_dataset: true
elasticsearch.dynamic_namespace: true

for the datastream collector and then tested it similarly to prometheus_input input package. permissions are correctly added to the api keys