[jira] [Commented] (FLINK-27329) Add default value of replica of JM pod and not declare it in example yamls

["Yang Wang (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-27329?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17525394#comment-17525394 ] 

Yang Wang commented on FLINK-27329:
-----------------------------------

Could we take this opportunity to review all the default values?

Another note is that we should always having the explicit default value when introducing new fields. It will help a lot to keep the compatibility. The old running CRs do not need to be changed.

> Add default value of replica of JM pod and not declare it in example yamls
> --------------------------------------------------------------------------
>
>                 Key: FLINK-27329
>                 URL: https://issues.apache.org/jira/browse/FLINK-27329
>             Project: Flink
>          Issue Type: Improvement
>          Components: Kubernetes Operator
>            Reporter: Biao Geng
>            Assignee: Biao Geng
>            Priority: Major
>
> Currently, we do not explicitly set the default value of `replica` in `JobManagerSpec`. As a result, Java sets the default value to be zero. 
> Besides, in our examples, we explicitly declare `replica` in `JobManagerSpec` to be 1. 
> After a deeper look when debugging the exception thrown in FLINK-27310, we find it would be better to set the default value to 1 for the `replica` field and remove the declaration in examples due to following reasons:
> 1. A normal Session or Application cluster should have at least one JM. The current default value, zero, does not follow the common case.
> 2. One JM can work for k8s HA mode as well and if users really want to launch a standby JM for faster recorvery, they can declare the value of `replica` field in the yaml file. In examples, we just use the new default value(i.e. 1), which should be fine.



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