feat: use StatefulSet to manage meta Pods

[arkbriar]

Signed-off-by: arkbriar [email protected]

What's changed and what's your intention?

PLEASE DO NOT LEAVE THIS EMPTY !!!

Please explain IN DETAIL what the changes are in this PR and why they are needed:

• Use StatefulSet instead of Deployment to manage the meta Pods. For reasons for this change, please refer to feat: start meta node with statefulset #311.
• I have deleted the tests for the meta workload objects. It's not expected, but adding tests in the current framework is hard. I will try to optimize the test cases later.
• This is a breaking change. When upgrading from the lower versions, a user must execute the following command to make the operator work again (but be noticed the commands have side effects of terminating the meta nodes).

kubectl delete deploy -l risingwave/component=meta -A

Checklist

• I have written the necessary docs and comments
• I have added necessary unit tests and integration tests

Refer to a related PR or issue link (optional)

close #311
relates to #313

[codecov]

Codecov Report

Merging #312 (3f5a0f4) into main (c868be4) will decrease coverage by 0.85%.
The diff coverage is 45.00%.

@@            Coverage Diff             @@
##             main     #312      +/-   ##
==========================================
- Coverage   76.46%   75.61%   -0.85%     
==========================================
  Files          52       52              
  Lines        5022     5028       +6     
==========================================
- Hits         3840     3802      -38     
- Misses       1115     1160      +45     
+ Partials       67       66       -1     

Flag	Coverage Δ
unittests	75.61% <45.00%> (-0.85%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/factory/risingwave_object_factory.go	90.47% <36.84%> (-3.20%)	⬇️
pkg/manager/risingwave_controller_manager_impl.go	41.29% <41.17%> (ø)
pkg/controller/risingwave_controller.go	65.64% <100.00%> (ø)

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[shanicky]

LGTM!
Thank you very much!
But we may need to add -endpoint=$(POD_NAME) to argsForMeta after the PR risingwavelabs/risingwave#7179 merged

[arkbriar]

But we may need to add -endpoint=$(POD_NAME) to argsForMeta after the PR risingwavelabs/risingwave#7179 merged

Let's update the operator, then.

[CAJan93]

What is the consequence of this? Will deleting the PVC Retention Policy Type also trigger a deletion of the PV? If so, do we want that? Does this mean that all pods loose their data if we scale the stateful set?

[arkbriar]

Nope, it means

• when deleting the StatefulSet, all PVCs from the PVC template will be deleted
• when scaling down the Pod of the StatefulSet, the corresponding PVC will also be deleted (and then the cloud controller should delete the PV as well)

You can check the details here.

For meta nodes, AFAIK, we won't have PVCs. Even if we have, that's for cache purposes and could be safely deleted.

[CAJan93]

LGTM

[arkbriar]

Since the test coverage drops, the mergify won't merge it. Will merge it manually. The improvement of the test coverage is planned in #313.