Delete source branch on merge (#1357)

Co-authored-by: Tapaszto, Istvan <istvan.tapaszto@msciintegration.onmicrosoft.com>

runatlantis.io/docs/repo-level-atlantis-yaml.md

@@ -46,11 +46,13 @@ need to be defined.
 ```yaml
 version: 3
 automerge: true
+delete_source_branch_on_merge: true
 projects:
 - name: my-project-name
   dir: .
   workspace: default
   terraform_version: v0.11.0
+  delete_source_branch_on_merge: true
   autoplan:
     when_modified: ["*.tf", "../modules/**.tf"]
     enabled: true
@@ -189,13 +191,15 @@ See [Custom Workflow Use Cases: Custom Backend Config](custom-workflows.html#cus
 ```yaml
 version:
 automerge:
+delete_source_branch_on_merge:
 projects:
 workflows:
 ```
 | Key                           | Type                                                     | Default | Required | Description                                                 |
 |-------------------------------|----------------------------------------------------------|---------|----------|-------------------------------------------------------------|
 | version                       | int                                                      | none    | **yes**  | This key is required and must be set to `3`                 |
-| automerge                     | bool                                                     | `false` | no       | Automatically merge pull request when all plans are applied |
+| automerge                     | bool                                                     | `false` | no       | Automatically merges pull request when all plans are applied|
+| delete_source_branch_on_merge | bool                                                     | `false` | no       | Automatically deletes the source branch on merge            |
 | projects                      | array[[Project](repo-level-atlantis-yaml.html#project)]  | `[]`    | no       | Lists the projects in this repo                             |
 | workflows<br />*(restricted)* | map[string: [Workflow](custom-workflows.html#reference)] | `{}`    | no       | Custom workflows                                            |
 
@@ -204,6 +208,7 @@ workflows:
 name: myname
 dir: mydir
 workspace: myworkspace
+delete_source_branch_on_merge:
 autoplan:
 terraform_version: 0.11.0
 apply_requirements: ["approved"]
@@ -216,6 +221,7 @@ workflow: myworkflow
 | dir                                    | string                | none        | **yes**  | The directory of this project relative to the repo root. For example if the project was under `./project1` then use `project1`. Use `.` to indicate the repo root.                                                    |
 | workspace                              | string                | `"default"` | no       | The [Terraform workspace](https://www.terraform.io/docs/state/workspaces.html) for this project. Atlantis will switch to this workplace when planning/applying and will create it if it doesn't exist.                |
 | autoplan                               | [Autoplan](#autoplan) | none        | no       | A custom autoplan configuration. If not specified, will use the autoplan config. See [Autoplanning](autoplanning.html).                                                                                               |
+| delete_source_branch_on_merge          | bool                  | `false`     | no       | Automatically deletes the source branch on merge                                                                                                                                                                      |
 | terraform_version                      | string                | none        | no       | A specific Terraform version to use when running commands for this project. Must be [Semver compatible](https://semver.org/), ex. `v0.11.0`, `0.12.0-beta1`.                                                          |
 | apply_requirements<br />*(restricted)* | array[string]         | none        | no       | Requirements that must be satisfied before `atlantis apply` can be run. Currently the only supported requirements are `approved` and `mergeable`. See [Apply Requirements](apply-requirements.html) for more details. |
 | workflow <br />*(restricted)*          | string                | none        | no       | A custom workflow. If not specified, Atlantis will use its default workflow.                                                                                                                                          |

runatlantis.io/docs/server-side-repo-config.md

@@ -42,7 +42,7 @@ repos:
 
   # allowed_overrides specifies which keys can be overridden by this repo in
   # its atlantis.yaml file.
-  allowed_overrides: [apply_requirements, workflow]
+  allowed_overrides: [apply_requirements, workflow, delete_source_branch_on_merge]
 
   # allowed_workflows specifies which workflows the repos that match 
   # are allowed to select.
@@ -52,6 +52,10 @@ repos:
   # workflows. If false (default), the repo can only use server-side defined
   # workflows.
   allow_custom_workflows: true
+
+  # delete_source_branch_on_merge defines whether the source branch would be deleted on merge
+  # If false (default), the source branch won't be deleted on merge
+  delete_source_branch_on_merge: true
 
   # pre_workflow_hooks defines arbitrary list of scripts to execute before workflow execution.
   pre_workflow_hooks: 
@@ -366,14 +370,15 @@ If you set a workflow with the key `default`, it will override this.
 :::
 
 ### Repo
-| Key                    | Type     | Default | Required | Description                                                                                                                                                                                                                                                                                              |
-|------------------------|----------|---------|----------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| id                     | string   | none    | yes      | Value can be a regular expression when specified as /<regex>/ or an exact string match. Repo IDs are of the form `{vcs hostname}/{org}/{name}`, ex. `github.com/owner/repo`. Hostname is specified without scheme or port. For Bitbucket Server, {org} is the **name** of the project, not the key. |
-| workflow               | string   | none    | no       | A custom workflow.                                                                                                                                                                                                                                                                                       |
-| apply_requirements     | []string | none    | no       | Requirements that must be satisfied before `atlantis apply` can be run. Currently the only supported requirements are `approved` and `mergeable`. See [Apply Requirements](apply-requirements.html) for more details.                                                                                    |
-| allowed_overrides      | []string | none    | no       | A list of restricted keys that `atlantis.yaml` files can override. The only supported keys are `apply_requirements` and `workflow`                                                                                                                                                                       |
-| allowed_workflows      | []string | none    | no       | A list of workflows that `atlantis.yaml` files can select from.                                                                                                                                                                        |
-| allow_custom_workflows | bool     | false   | no       | Whether or not to allow [Custom Workflows](custom-workflows.html).                                                                                                                                                                       |
+| Key                           | Type     | Default | Required | Description                                                                                                                                                                                                                                                                                              |
+|-------------------------------|----------|---------|----------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| id                            | string   | none    | yes      | Value can be a regular expression when specified as /<regex>/ or an exact string match. Repo IDs are of the form `{vcs hostname}/{org}/{name}`, ex. `github.com/owner/repo`. Hostname is specified without scheme or port. For Bitbucket Server, {org} is the **name** of the project, not the key. |
+| workflow                      | string   | none    | no       | A custom workflow.                                                                                                                                                                                                                                                                                       |
+| apply_requirements            | []string | none    | no       | Requirements that must be satisfied before `atlantis apply` can be run. Currently the only supported requirements are `approved` and `mergeable`. See [Apply Requirements](apply-requirements.html) for more details.                                                                                    |
+| allowed_overrides             | []string | none    | no       | A list of restricted keys that `atlantis.yaml` files can override. The only supported keys are `apply_requirements`, `workflow` and `delete_source_branch_on_merge`                                                                                                                                      |
+| allowed_workflows             | []string | none    | no       | A list of workflows that `atlantis.yaml` files can select from.                                                                                                                                                                        |
+| allow_custom_workflows        | bool     | false   | no       | Whether or not to allow [Custom Workflows](custom-workflows.html).                                                                                                                                                                       |
+| delete_source_branch_on_merge | bool     | false   | no       | Whether or not to delete the source branch on merge (only AzureDevOps and GitLab support)                                                                                                                                                                      |
 
 
 :::tip Notes

server/events/apply_command_runner.go

@@ -158,7 +158,7 @@ func (a *ApplyCommandRunner) Run(ctx *CommandContext, cmd *CommentCommand) {
 	a.updateCommitStatus(ctx, pullStatus)
 
 	if a.autoMerger.automergeEnabled(projectCmds) {
-		a.autoMerger.automerge(ctx, pullStatus)
+		a.autoMerger.automerge(ctx, pullStatus, a.autoMerger.deleteSourceBranchOnMergeEnabled(projectCmds))
 	}
 }
 

server/events/automerger.go

@@ -12,7 +12,7 @@ type AutoMerger struct {
 	GlobalAutomerge bool
 }
 
-func (c *AutoMerger) automerge(ctx *CommandContext, pullStatus models.PullStatus) {
+func (c *AutoMerger) automerge(ctx *CommandContext, pullStatus models.PullStatus, deleteSourceBranchOnMerge bool) {
 	// We only automerge if all projects have been successfully applied.
 	for _, p := range pullStatus.Projects {
 		if p.Status != models.AppliedPlanStatus {
@@ -29,7 +29,9 @@ func (c *AutoMerger) automerge(ctx *CommandContext, pullStatus models.PullStatus
 
 	// Make the API call to perform the merge.
 	ctx.Log.Info("automerging pull request")
-	err := c.VCSClient.MergePull(ctx.Pull)
+	var pullOptions models.PullRequestOptions
+	pullOptions.DeleteSourceBranchOnMerge = deleteSourceBranchOnMerge
+	err := c.VCSClient.MergePull(ctx.Pull, pullOptions)
 
 	if err != nil {
 		ctx.Log.Err("automerging failed: %s", err)
@@ -48,3 +50,9 @@ func (c *AutoMerger) automergeEnabled(projectCmds []models.ProjectCommandContext
 		// Otherwise we check if this repo is configured for automerging.
 		(len(projectCmds) > 0 && projectCmds[0].AutomergeEnabled)
 }
+
+// deleteSourceBranchOnMergeEnabled returns true if we should delete the source branch on merge in this context.
+func (c *AutoMerger) deleteSourceBranchOnMergeEnabled(projectCmds []models.ProjectCommandContext) bool {
+	//check if this repo is configured for automerging.
+	return (len(projectCmds) > 0 && projectCmds[0].DeleteSourceBranchOnMerge)
+}

server/events/command_runner.go

@@ -339,6 +339,4 @@ func (c *DefaultCommandRunner) logPanics(baseRepo models.Repo, pullNum int, logg
 	}
 }
 
-// automergeComment is the comment that gets posted when Atlantis automatically
-// merges the PR.
 var automergeComment = `Automatically merging because all plans have been successfully applied.`

server/events/command_runner_test.go

@@ -649,8 +649,12 @@ func TestApplyWithAutoMerge_VSCMerge(t *testing.T) {
 	autoMerger.GlobalAutomerge = true
 	defer func() { autoMerger.GlobalAutomerge = false }()
 
+	pullOptions := models.PullRequestOptions{
+		DeleteSourceBranchOnMerge: false,
+	}
+
 	ch.RunCommentCommand(fixtures.GithubRepo, &fixtures.GithubRepo, nil, fixtures.User, fixtures.Pull.Num, &events.CommentCommand{Name: models.ApplyCommand})
-	vcsClient.VerifyWasCalledOnce().MergePull(modelPull)
+	vcsClient.VerifyWasCalledOnce().MergePull(modelPull, pullOptions)
 }
 
 func TestRunApply_DiscardedProjects(t *testing.T) {
@@ -688,7 +692,8 @@ func TestRunApply_DiscardedProjects(t *testing.T) {
 	When(workingDir.GetPullDir(matchers.AnyModelsRepo(), matchers.AnyModelsPullRequest())).
 		ThenReturn(tmp, nil)
 	ch.RunCommentCommand(fixtures.GithubRepo, &fixtures.GithubRepo, &pull, fixtures.User, fixtures.Pull.Num, &events.CommentCommand{Name: models.ApplyCommand})
-	vcsClient.VerifyWasCalled(Never()).MergePull(matchers.AnyModelsPullRequest())
+
+	vcsClient.VerifyWasCalled(Never()).MergePull(matchers.AnyModelsPullRequest(), matchers.AnyModelsPullRequestOptions())
 }
 
 func TestRunCommentCommand_DrainOngoing(t *testing.T) {

server/events/models/models.go

@@ -171,6 +171,13 @@ type PullRequest struct {
 	BaseRepo Repo
 }
 
+// PullRequestOptions is used to set optional paralmeters for PullRequest
+type PullRequestOptions struct {
+	// When DeleteSourceBranchOnMerge flag is set to true VCS deletes the source branch after the PR is merged
+	// Applied by GitLab & AzureDevops
+	DeleteSourceBranchOnMerge bool
+}
+
 type PullRequestState int
 
 const (
@@ -391,6 +398,8 @@ type ProjectCommandContext struct {
 	// PolicySets represent the policies that are run on the plan as part of the
 	// policy check stage
 	PolicySets valid.PolicySets
+	// DeleteSourceBranchOnMerge will attempt to allow a branch to be deleted when merged (AzureDevOps & GitLab Support Only)
+	DeleteSourceBranchOnMerge bool
 }
 
 // GetShowResultFileName returns the filename (not the path) to store the tf show result

server/events/project_command_builder.go

@@ -25,6 +25,8 @@ const (
 	DefaultParallelApplyEnabled = false
 	// DefaultParallelPlanEnabled is the default for the parallel plan setting.
 	DefaultParallelPlanEnabled = false
+	// DefaultDeleteSourceBranchOnMerge being false is the default setting whether or not to remove a source branch on merge
+	DefaultDeleteSourceBranchOnMerge = false
 )
 
 func NewProjectCommandBuilder(
@@ -235,6 +237,7 @@ func (p *DefaultProjectCommandBuilder) buildPlanAllCommands(ctx *CommandContext,
 					commentFlags,
 					repoDir,
 					repoCfg.Automerge,
+					mergedCfg.DeleteSourceBranchOnMerge,
 					repoCfg.ParallelApply,
 					repoCfg.ParallelPlan,
 					verbose,
@@ -261,6 +264,7 @@ func (p *DefaultProjectCommandBuilder) buildPlanAllCommands(ctx *CommandContext,
 					commentFlags,
 					repoDir,
 					DefaultAutomergeEnabled,
+					pCfg.DeleteSourceBranchOnMerge,
 					DefaultParallelApplyEnabled,
 					DefaultParallelPlanEnabled,
 					verbose,
@@ -451,10 +455,12 @@ func (p *DefaultProjectCommandBuilder) buildProjectCommandCtx(ctx *CommandContex
 	var projCtxs []models.ProjectCommandContext
 	var projCfg valid.MergedProjectCfg
 	automerge := DefaultAutomergeEnabled
+	deleteBranchOnMerge := DefaultDeleteSourceBranchOnMerge
 	parallelApply := DefaultParallelApplyEnabled
 	parallelPlan := DefaultParallelPlanEnabled
 	if repoCfgPtr != nil {
 		automerge = repoCfgPtr.Automerge
+		deleteBranchOnMerge = projCfg.DeleteSourceBranchOnMerge
 		parallelApply = repoCfgPtr.ParallelApply
 		parallelPlan = repoCfgPtr.ParallelPlan
 	}
@@ -477,8 +483,9 @@ func (p *DefaultProjectCommandBuilder) buildProjectCommandCtx(ctx *CommandContex
 					commentFlags,
 					repoDir,
 					automerge,
-					parallelApply,
+					deleteBranchOnMerge,
 					parallelPlan,
+					parallelApply,
 					verbose,
 				)...)
 		}
@@ -492,8 +499,9 @@ func (p *DefaultProjectCommandBuilder) buildProjectCommandCtx(ctx *CommandContex
 				commentFlags,
 				repoDir,
 				automerge,
-				parallelApply,
+				deleteBranchOnMerge,
 				parallelPlan,
+				parallelApply,
 				verbose,
 			)...)
 	}
@@ -503,7 +511,6 @@ func (p *DefaultProjectCommandBuilder) buildProjectCommandCtx(ctx *CommandContex
 	}
 
 	return projCtxs, nil
-
 }
 
 // validateWorkspaceAllowed returns an error if repoCfg defines projects in