Atlantis plan with terraform 1.4.0 returns zero output when nothing is changed

[adriantr]

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Overview of the Issue

Atlantis plan doesn't seem to pick up the last line of plan output which contains info about nothing being changed.

Reproduction Steps

Logs

Environment details

Additional Context

[AlessioCasco]

This is an intentional change in terraform 1.4.0

The Terraform plan renderer has been completely rewritten to aid with future Terraform Cloud integration. Users should not see any material change in the plan output between 1.3 and 1.4. If you notice any significant differences, or if Terraform fails to plan successfully due to rendering problems, please open a bug report issue.

If you have specified a different terraform version in Atlantis, it may be that you are also affected by #3199 where latest seems to be always used.

[wyardley]

This also seems to create a single empty line diff vs. "no changes", at least with one provider we use

[wyardley]

Based on hashicorp/terraform#32815, hashicorp/terraform#32822 seems to have a fix

[wyardley]

Maybe Atlantis should use something else to see if the plan had any changes, whether that's returning a generic message if there's no diff and / or if the exit code shows no changes, or chomp off that trailing newline at least and use that to figure out if there are changes?

It does look like the CLI will exit 0 if no changes, or non-zero otherwise if -detailed-exitcode is used, so that might be the most reliable way to figure out if there are changes or not?

[nitrocode]

Thanks for adding those tickets. Hopefully this will be released soon in 1.4.1.

We currently use a set of regex to determine no changes if I recall correctly. Perhaps using the exit code would work. Unsure how that exit code has changed across different terraform versions though.

[wyardley]

I don't remember exactly, but had the zip of 0.12 locally, and that's got the same info:

  -detailed-exitcode  Return detailed exit codes when the command exits. This
                      will change the meaning of exit codes to:
                      0 - Succeeded, diff is empty (no changes)
                      1 - Errored
                      2 - Succeeded, there is a diff

So I'm guessing that goes relatively far back, and is probably as stable or more stable than looking at the output.

[nitrocode]

Does 1.4.1 fix this issue?

Let's see if that fixes it before looking into the exit code

[wyardley]

Confirmed 1.4.1 resolves the issue

[nitrocode]

Thank you!