How to detect changes in plan step

[palakraina]

Hi team,
My plan step looks like this

- name: Terraform Plan with comment
        id: plan
        uses: OP5dev/tf-via-pr@v13
        with:
          working-directory: "./xyz"
          command: plan                     
          validate: true                    
          format: false
          comment-pr: always                    
          arg-detailed-exitcode: true
          show-args: true

   In my apply step, I want to run only if I detect any changes in plan step. How to get it correctly?
   Context: I want to keep my apply step separate and only run if `plan` step has detected changes. I tried using exit code but the step always gives exitcode 0.

[rdhar]

This is likely because of "hashicorp/setup-terraform" being used without terraform_wrapper: false, as documented in their repo's open issue. Here's how to work around it to meet your given requirements:

- name: Checkout repo
  uses: actions/checkout@v4

- name: Setup Terraform
  uses: hashicorp/setup-terraform@v3
  with:
    terraform_wrapper: false

- name: Terraform Plan
  id: plan
  uses: op5dev/tf-via-pr@v13
  with:
    working-directory: "./xyz"
    command: plan
    arg-lock: false
    validate: true

- name: Terraform Apply
  uses: op5dev/tf-via-pr@v13
  if: steps.plan.outputs.exitcode == 2
  with:
    working-directory: "./xyz"
    command: apply
    arg-lock: true

You don't need to give the following inputs, as they are set automatically to sensible defaults:

• comment-pr
• arg-detailed-exitcode
• show-args
• format

---

There are plenty more workflow examples you can pick-and-mix from.

#1 example ⤴ Runs on pull_request (plan) and push (apply) events with Terraform, AWS authentication and cache.	#2 example ⤴ Runs on pull_request (plan) and merge_group (apply) events with OpenTofu in matrix strategy.
#3 example ⤴ Runs on pull_request (plan) and push (apply) events with fmt/validate checks and TFLint.	#4 example ⤴ Runs on pull_request (plan) and push (apply) events with conditional jobs based on plan file.
#5 example ⤴ Runs on labeled and workflow_dispatch manual events on GitHub Enterprise (GHE) self-hosted runner.	#6 example ⤴ Runs on schedule cron event with -refresh-only to open an issue on configuration drift.

[palakraina]

Thank you so much!
It worked using terraform_wrapper: false.
Soo helpful!
I actually found another workaround by checking needs.plan.outputs.diff != ''
I was going through the actions and realise it sets diff as well which also helped in finding if anything was changed.
but, I prefer checking exitcode

[rdhar]

That's great to hear this answer solved it! Yes, I'd trust exitcode over diff-based workarounds as well.

The above snippet should also work for you, without needing any of the extraneous inputs.

Please consider ⭐ this project, if you or your team find it useful.

[palakraina]

Yes, I removed the extraneous inputs and it works fine! Definitely, this project is a ⭐ ; (did it)
This is super useful!
I have got another question - I had another PR and realised just now that `changes comment got pushed to both PRs - even though the other one was unrelated. Is there anything I could be missing to avoid this?
Some context : I have different workflows based on the folder/file changed.
I have two PRs when I updated the second PR, plan changes got also commented out in my first unrelated PR.

[rdhar]

That seems odd, it shouldn't be possible for this action to update a comment to an unrelated PR from which it was triggered.

It might help share (obfuscated) snippets of your workflow in order to troubleshoot.

[palakraina]

I will try to reproduce again and share. For now, the major concern is resolved around getting changes for apply step. Thanks for your quick help