Fix rejoin_after_leave behavior

[anth0d]

This will effectively change the default behavior of Serf to not rejoin after leave, which (I believe...) is actually the documented behavior. But this could be perceived as a breaking change by some cluster operators who may be accustomed to server nodes ignoring leave events.

Alternative approaches which would not change the default behavior would be

• use a bool pointer in this config field in order to be able to discern nil (not configured) from intentionally false, and default to true as exists today
• introduce a new config field disable_rejoin_after_leave which would default to false and therefore continue to produce the current behavior

In any case, docs probably need to be updated here and if necessary, a behavior change be communicated out.

[vercel]

@anth0d is attempting to deploy a commit to the HashiCorp Team on Vercel.

A member of the Team first needs to authorize it.

[tgross]

Hi @anth0d this looks great! A few remaining items:

• If you run make cl that'll create a changelog entry file (it should read something like "Fixed a bug where the rejoin_after_leave configuration was not respected).
• This does seem like the sort of thing that could catch out users, so maybe we add a note to the version-specific upgrade guide for Nomad 1.4.4 as well. That'll be found in https://github.com/hashicorp/nomad/blob/main/website/content/docs/upgrade/upgrade-specific.mdx
• For some reason GHA didn't run on this PR, so we haven't run most of the CI testing on it. I'll try to figure that out but if you have any suggestions I'm all ears 😁

[tgross]

@anth0d I think we've got the CI issue fixed. Would you mind rebasing on main to verify that?

[tgross]

One last docs item to fix and this will be good-to-go @anth0d!

[anth0d]

Thanks @tgross, could you authorize the new preview app deployment?

[tgross]

LGTM! Thanks for sticking this out @anth0d!

Preview link for docs: https://nomad-1wafiobcv-hashicorp.vercel.app/nomad/docs/upgrade/upgrade-specific#server-rejoin_after_leave-default-false-now-enforced

[github-actions]

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