Plan stale when applying PR that only changes the lock file

[florianmutter]

Question

We have a PR where we moved terraform files to a different folder. tfaction updated the lock file in the PR and plan was successful ("No changes"). After merging apply failed and said the plan is stale. It created a followup PR that we can merge and nothing fails.

Does anyone have an idea what might beging wrong here? There was no PR merged inbetween.

Background of the question

No response

Example Code

No response

Note

No response

[suzuki-shunsuke]

the lock file means .terraform.lock.hcl, right?

After merging apply failed and said the plan is stale.

tfaction stores the plan file at GitHub Artifacts and uses it when running terraform apply.

https://suzuki-shunsuke.github.io/tfaction/docs/feature/plan-file

tfaction/terraform-apply/download_plan_file.sh

Lines 1 to 26 in 9d8c235

	#!/usr/bin/env bash
	set -euo pipefail
	filename=tfplan.binary
	artifact_name=terraform_plan_file_${TFACTION_TARGET//\//__}
	branch=$CI_INFO_HEAD_REF
	workflow=$PLAN_WORKFLOW_NAME
	pr_head_sha=$(jq -r ".head.sha" "$CI_INFO_TEMP_DIR/pr.json")
	body=$(gh run list -w "$workflow" -b "$branch" -L 1 --json headSha,databaseId --jq '.[0]')
	run_id=$(echo "$body" | jq -r ".databaseId")
	head_sha=$(echo "$body" | jq -r ".headSha")
	if [ "$head_sha" != "$pr_head_sha" ]; then
	echo "::error::workflow run's headSha is different from the associated pull request's head sha"
	github-comment post -k invalid-workflow-sha \
	-var "wf_sha:$head_sha" -var "pr_sha:$pr_head_sha"
	exit 1
	fi
	tempdir=$(mktemp -d)
	gh run download -D "$tempdir" -n "$artifact_name" "$run_id"
	cp "$tempdir/$filename" tfplan.binary

I think your failure means the plan file is stale, but basically tfaction updates plan files if necessary, so this issue won't occur.

https://suzuki-shunsuke.github.io/tfaction/docs/feature/auto-update-related-prs

If you merged pull requests regarding the same working directory at the same time,
then the issue may occur.

1. PR A is merged
2. PR B is merged
3. apply of PR A is run
4. tfaction can't update the plan file of PR B because PR B is already merged
5. apply of PR B fails because the plan file is stale

[florianmutter]

After carefully checking I noticed a run of the old pipeline between the plan creation and running apply. This was the old pipeline that we are migration away from.

Sorry for taking up your time again and thank you very much for the help