[IMPROVEMENT] Add PVC namespace to longhorn_volume metrics

[antoninferrand]

Is your improvement request related to a feature? Please describe (👍 if you like this request)

In [IMPROVEMENT] Add pvc name to longhorn_volume metrics you added the PVC name to the volume metrics, however to entirely define a PVC we also need the namespace (multiple PVC can have the same name if they are in different namespaces).

Describe the solution you'd like

Add a "namespace" label to all longhorn_volume metrics, and fill it with the PVC namespace from v.Status.KubernetesStatus.Namespace.

Describe alternatives you've considered

n/a

Additional context

n/a

PRs

As the change is very similar to what you did a few months ago, I created the same PRs, let me know if this is a mistake.

• feat(metrics): add pvc namespace to volume metrics
• test(metrics): PVC namespace included in volume metrics
• doc(metrics): add pvc namespace to volume metrics

[longhorn-io-github-bot]

Pre Ready-For-Testing Checklist

• Where is the reproduce steps/test steps documented?
  The reproduce steps/test steps are at:

• Is there a workaround for the issue? If so, where is it documented?
  The workaround is at:

• Does the PR include the explanation for the fix or the feature?

• Does the PR include deployment change (YAML/Chart)? If so, where are the PRs for both YAML file and Chart?
  The PR for the YAML change is at:
  The PR for the chart change is at:

• Have the backend code been merged (Manager, Engine, Instance Manager, BackupStore etc) (including backport-needed/*)?
  The PR is at
  feat(metrics): add pvc namespace to volume metrics longhorn-manager#2284

• Which areas/issues this PR might have potential impacts on?
  Area
  Issues

• If labeled: require/LEP Has the Longhorn Enhancement Proposal PR submitted?
  The LEP PR is at

• If labeled: area/ui Has the UI issue filed or ready to be merged (including backport-needed/*)?
  The UI issue/PR is at

• If labeled: require/doc Has the necessary document PR submitted or merged (including backport-needed/*)?
  The documentation issue/PR is at
  doc(metrics): add pvc namespace to volume metrics website#796

• If labeled: require/automation-e2e Has the end-to-end test plan been merged? Have QAs agreed on the automation test case? If only test case skeleton w/o implementation, have you created an implementation issue (including backport-needed/*)
  The automation skeleton PR is at
  The automation test case PR is at
  The issue of automation test case implementation is at (please create by the template)
  test(metrics): PVC namespace included in volume metrics longhorn-tests#1585

• If labeled: require/automation-engine Has the engine integration test been merged (including backport-needed/*)?
  The engine automation PR is at

• If labeled: require/manual-test-plan Has the manual test plan been documented?
  The updated manual test plan is at

• If the fix introduces the code for backward compatibility Has a separate issue been filed with the label release/obsolete-compatibility?
  The compatibility issue is filed at

[roger-ryao]

Verified on master-head 20231115

• longhorn master-head 74d829d
• longhorn-manager master-head longhorn/longhorn-manager@d49f1f9

Test Steps:

1. Create vol-0 with PV/PVC in the longhorn-system namespace.
2. Create vol-1 with PV/PVC in the local namespace.
3. Create vol-2 with PV/PVC in the default namespace.
4. Create vol-3 without PV/PVC
5. Attach volumes to the node.
6. Execute the command curl -sSL http://$longhorn_manager_ip:$longhorn_backend_service_port/metrics | grep longhorn_volume | grep pvc_namespace

Result Passed

• After executing the command, we observed the corresponding PVC value in the metrics.
• require/auto-e2e-test
  • add case test_volume_metrics longhorn-tests#1531
• require/doc
  • doc(metrics): add pvc namespace to volume metrics website#796