feat(api): add has_git_branch variable to purge (#5765)

Author: richardlt

docs/content/docs/concepts/workflow/retention.md

@@ -29,6 +29,7 @@ Retention policy is defined through a lua condition. This condition should be ev
 
 You will be able to use these variables in conditions:
   * **run_days_before** (number): count of days between Workflow creation date and now.
+  * **has_git_branch** (string: true|false): True if a *git.branch* variable is set **(added in 0.48.1)**.
   * **git_branch_exist** (string: true|false): True if a *git.branch* variable is set and branch still exists on the git repository.
   * **run_status** (string: Success|Fail|...): the Workflow Run status.
   * **gerrit_change_merged** (string: true|false): to identify if the gerrit change has been merged.
@@ -41,6 +42,19 @@ Examples:
   -- Keep Run for 365 days
   return run_days_before < 365
 ````
+```lua
+  -- Keep Run for 365 days if git_branch is set and exists in VCS or only 2 days for removed branches
+  -- Else keep Run for 365 days if no git_branch info is set
+  if(has_git_branch == "true") then
+    if(git_branch_exist == "true") then
+      return run_days_before < 365
+    else
+      return run_days_before < 2
+    end
+  else 
+    return run_days_before < 365
+  end
+```
 ```lua
   -- Keep Run for ever
   return true

engine/api/purge/purge_run.go

@@ -28,6 +28,7 @@ type MarkAsDeleteOptions struct {
 const (
 	RunStatus          = "run_status"
 	RunDaysBefore      = "run_days_before"
+	RunHasGitBranch    = "has_git_branch"
 	RunGitBranchExist  = "git_branch_exist"
 	RunChangeExist     = "gerrit_change_exist"
 	RunChangeMerged    = "gerrit_change_merged"
@@ -36,7 +37,7 @@ const (
 )
 
 func GetRetentionPolicyVariables() []string {
-	return []string{RunDaysBefore, RunStatus, RunGitBranchExist, RunChangeMerged, RunChangeAbandoned, RunChangeDayBefore, RunChangeExist}
+	return []string{RunDaysBefore, RunStatus, RunHasGitBranch, RunGitBranchExist, RunChangeMerged, RunChangeAbandoned, RunChangeDayBefore, RunChangeExist}
 }
 
 func markWorkflowRunsToDelete(ctx context.Context, store cache.Store, db *gorp.DbMap, workflowRunsMarkToDelete *stats.Int64Measure) error {
@@ -218,10 +219,14 @@ func purgeComputeVariables(ctx context.Context, luaCheck *luascript.Check, run s
 	}
 
 	// If we have a branch in payload, check if it exists on repository branches list
-	if b, has := vars["git.branch"]; has {
-		_, exist := branchesMap[b]
-		vars[RunGitBranchExist] = strconv.FormatBool(exist)
+	b, has := vars["git.branch"]
+	var exist bool
+	if has {
+		_, exist = branchesMap[b]
 	}
+	vars[RunHasGitBranch] = strconv.FormatBool(has)
+	vars[RunGitBranchExist] = strconv.FormatBool(exist)
+
 	vars[RunStatus] = run.Status
 
 	varsFloats[RunDaysBefore] = math.Floor(time.Now().Sub(run.LastModified).Hours() / 24)