metrics: support multi-k8s in grafana dashboards (#4658)

[ti-chi-bot]

This is an automated cherry-pick of #4658

Signed-off-by: just1900 legendj228@gmail.com

What problem does this PR solve?

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.

Issue Number: close #4665

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

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation
• Need to update key monitor metrics in both TiCDC document and official document

Release note

metrics: support multi-k8s in grafana dashboards

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has not been approved.

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[ti-chi-bot]

@ti-chi-bot: This cherry pick PR is for a release branch and has not yet been approved by release team.
Adding the do-not-merge/cherry-pick-not-approved label.

To merge this cherry pick, it must first be approved by the collaborators.

AFTER it has been approved by collaborators, please ping the release team in a comment to request a cherry pick review.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (release-5.3@9c6e109). Click here to learn what that means.
The diff coverage is n/a.

@@               Coverage Diff                @@
##             release-5.3      #4708   +/-   ##
================================================
  Coverage               ?   55.6050%           
================================================
  Files                  ?        222           
  Lines                  ?      23791           
  Branches               ?          0           
================================================
  Hits                   ?      13229           
  Misses                 ?       9231           
  Partials               ?       1331           

[purelind]

/run-integration-test

[ti-chi-bot]

@ti-chi-bot: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
jenkins-ticdc/verify	db08c03	link	true	/test verify

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[ti-chi-bot]

@ti-chi-bot: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
jenkins-ticdc/verify	db08c03	link	true	/test verify

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[ti-chi-bot]

This pull request is closed because its related version has closed automatic cherry-picking.
If it's still needed, you can reopen it or just regenerate it using bot,
see:

https://prow.tidb.net/command-help#cherrypick
https://book.prow.tidb.net/#/plugins/cherrypicker