feat: Flag to disable custom [Atlantis] commit messages on PR merge

[oliverisaac]

what

When PR's are merged in they are given the commit message:

[Atlantis] Automatically merging after successful apply

This makes it hard to track which PR applies to which commit.

This flag would allow us to turn off this behavior.

why

• The custom [Atlantis] Automatically merging after successful apply message makes it hard to audit which PR applies to which commit.

tests

• I duplicated tests related to the delete_source_branch_on_merge flag

references

The merge commit message is optional for gitlab and azdo:

GitLab: https://docs.gitlab.com/ee/api/merge_requests.html#merge-a-merge-request

AzDo: https://learn.microsoft.com/en-us/rest/api/azure/devops/git/pull-requests/update?view=azure-devops-rest-5.1#gitpullrequestcompletionoptions

[jamengual]

isn't this possible with Custom templates? did you look into that?

[oliverisaac]

I don't think so? The commit message is hard coded in the azure provider: https://github.com/runatlantis/atlantis/pull/3120/files#diff-58c908ca04501c732469c627f38c2df5c07a233e149bf7d49396dc2550c20d99L328

Unless custom templates would be used in another way?

[jamengual]

@krrrr38 do you happen to know?

[krrrr38]

Custom template manages only PR comments. Currently commit messages are not managed by template.

---

BTW how about add just pull number into commit message? New config seems to be too much.

example diff

diff --git a/server/events/vcs/common/common.go b/server/events/vcs/common/common.go
index 7a41b1d8..a1de298b 100644
--- a/server/events/vcs/common/common.go
+++ b/server/events/vcs/common/common.go
@@ -3,12 +3,15 @@
 package common

 import (
+       "fmt"
        "math"
 )

 // AutomergeCommitMsg is the commit message Atlantis will use when automatically
 // merging pull requests.
-const AutomergeCommitMsg = "[Atlantis] Automatically merging after successful apply"
+func AutomergeCommitMsg(pullNum int) string {
+       return fmt.Sprintf("[Atlantis] Automatically merging after successful apply #%d", pullNum)
+}

 // SplitComment splits comment into a slice of comments that are under maxSize.
 // It appends sepEnd to all comments that have a following comment.
diff --git a/server/events/vcs/gitlab_client.go b/server/events/vcs/gitlab_client.go
index e530ab80..84715f43 100644
--- a/server/events/vcs/gitlab_client.go
+++ b/server/events/vcs/gitlab_client.go
@@ -295,7 +295,7 @@ func (g *GitlabClient) WaitForSuccessPipeline(ctx context.Context, pull models.P

 // MergePull merges the merge request.
 func (g *GitlabClient) MergePull(pull models.PullRequest, pullOptions models.PullRequestOptions) error {
-       commitMsg := common.AutomergeCommitMsg
+       commitMsg := common.AutomergeCommitMsg(pull.Num)

[LanceSandino]

This would be a really cool feature to have 😄

[nitrocode]

I agree with @krrrr38 . Instead of adding a new flag, it seems better to mention the PR number in the merge message.

What do you think @oliverisaac ?

[oliverisaac]

It seems better to mention the PR number in the merge message.

I'm totally okay with that answer: I was trying to maintain backwards compatibility but if we're okay with modifying the commit message I'm all for that :) Much easier!

[oliverisaac]

I've rebased the PR as discussed above

[nitrocode]

@oliverisaac please merge the default branch into the feature branch again in order to resolve the test failure

[oliverisaac]

I've merged in main, thanks!

[nitrocode]

Thank you @oliverisaac !