metrics: support multi-k8s in grafana dashboards (#4099)

[ti-chi-bot]

This is an automated cherry-pick of #4099

Signed-off-by: just1900 [email protected]

What problem does this PR solve?

Issue Number: ref #4129

Problem Summary:

K8s community and organizations are increasingly deploying multiple Kubernetes clusters to improve availability, isolation and scalability. Since TiDB Operator have support deploying tidb across-kubernetes, this PR will address the multi-k8s issue without affecting existing single-cluster use case.

What is changed and how it works?

What's Changed:

• add a k8s_cluster label in all expr
• add k8s_cluster variable in Grafana templating

How it works:

• For users with single-k8s, nothing need to be changed, just use it as before.
• For users with multi-k8s:
  • first add kubernetes label to identify k8s cluster in your prometheus' external_labels.
  • set field "hide" to '0' to show variables in grafana via sed -i s/"hide": 2/"hide": 0/g <path/to/dashboard.json>
  • load it to grafana

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

metrics: support multi-k8s in grafana dashboards

[ti-chi-bot]

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[JaySon-Huang]

conflict

[JaySon-Huang]

conflict

[just1900]

working on it

[JaySon-Huang]

Resolve conflict in #4213