fix: Update workspace list implementation to tolerate warnings present in stdout output

[SarahFrench]

Note: This is likely to be flaky once warnings start being present in the command's stdout output. The best resolution is to add machine-readable output support to the workspace commands! I'm working on this.

Related Issue

N/A

Description

I'm proposing some changes to the workspace list command to migrate it from using cli.Ui to view.View when rendering human-readable output. The command doesn't support machine-readable output, yet.

That migration process will cause warning diagnostics to be sent to stdout instead of stderr, which is what happens currently. Due to this, terraform-exec is written to parse workspace list's human-readable output under the assumption that stdout will only include the list of workspaces. This assumption is currently correct but might not be in future.

If a warning is present in stdout the current parsing code will assume every non-empty line is a workspace name.

This PR introduces some light filtering of non-empty lines to determine if the string is part of a warning or a workspace name. This is based on how Terraform validates workspace names; URL escaping.

Rollback Plan

• If a change needs to be reverted, we will roll out an update to the code within 7 days.

Changes to Security Controls

N/A

[SarahFrench]

This change is motivated by this update to Terraform Core, but it can be merged independently of that PR. Due to that I'm opening this PR for review.

[radeksimko]

I don't really like processing the output like that but aside from what you already suggested and are working on (JSON output) I don't think we have any better options sadly. 😹 😭

[radeksimko]

oof, this is precisely why we need JSON output. Kinda regret we even added support for this command here so early. 😂 😭

[SarahFrench]

FWIW I felt very dirty adding this code 😭 , but I'm working on JSON output!

[SarahFrench]

I'll save merging this for when the JSON output for workspace list is further along. Potentially this PR could be merged alongside a change to add -json support here in terraform-exec.

[radeksimko]

I'll save merging this for when the JSON output for workspace list is further along. Potentially this PR could be merged alongside a change to add -json support here in terraform-exec.

I think that merging both at the same time makes sense but keep in mind that we tend to maintain some level of compatibility within terraform-exec and so like with other commands with discussed, this implies initially introducing the JSON version as WorkspaceListJSON and later, in terraform-exec v1 making WorkspaceList consume JSON by default and phasing out the *JSON suffixed variation.

All that is to say that this patch will stay around until at least v1 and JSON cannot directly replace it yet.