cli: Restore -lock and -lock-timeout init flags

[alisdair]

The -lock and -lock-timeout flags were removed in #27464 prior to the release of 1.0 as they were thought to have no effect. This is not true in the case of state migrations when changing backends. This commit restores these flags, and adds test coverage for locking during backend state migration.

Documentation does not need to be updated, as it currently shows that the flags are present. I intend to backport this change to 1.0 because I believe this removal was a bug.

Fixes #29765.

[apparentlymart]

While updating the usages for these boolean options we've gradually been trying to update them to show the argument as the user would type it rather than the default behavior, because historically folks got confused by us only showing a usage that changes nothing.

In this case I think -lock is already the default (please correct me if I'm wrong!), so I'd prefer to write this as something like:

  -lock=false         Don't hold a state lock during the operation. This is
                      dangerous if others might concurrently run commands
                      against the same workspace.

(I took the above from the terraform plan -help, which we updated as part of the CLI consistency work we did in the run-up to v1.0.)

It seems like I neglected to update terraform init -help in general during that work, for whatever reason, since I see various other ones here that seem to just re-state the default, rather than showing how to disable the thing that's on by default:

• -backend=true
• -get=true
• -input=true

I'm not sure why I didn't update these along with the others in that earlier work, but if you'd be willing to do some "while in the area" updates here it'd be nice to get these all lined up with the other usages. Other than -input I don't think the rest of these are present in any other commands so there isn't a convenient existing wording to copy from somewhere else, but of course the general idea here is to just reword it to be a "don't" or "disable" sentence instead of a "do" or "enable" sentence, in each case.

I also notice -upgrade=false here, which I think ought to just be -upgrade and talk about overriding the default behavior of selecting exactly the version recorded in the lock file, if any.

[alisdair]

Good catch, thanks! I've updated the help output for these arguments.

[jspiro]

Thank you!!!!!

[github-actions]

I'm going to lock this pull request because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active contributions.
If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.