Ensure workflow status failure if command fails in backendless mode (#…

…1760)

Fixes #1658

Error handling in backendless mode was incorrect, resulting in the
workflow exit status to be success even if the command execution failed.
This patch addresses this issue.

The following are some additional notes of this fix:

- When `allAppliesSuccessful` is false, we need to call
  `ReportErrorAndExit()` to ensure that the workflow fails with a
  non-zero exit status.
- Since `ReportErrorAndExit()` invokes `os.Exit()` immediately, it
  should be called after setting the status of the pull request.
- Contrary to intuition, `atLeastOneApply` is counted even if plan
  command, so we need to use `scheduler.IsPlanJobs()` to determine if
  the current workflow is plan or apply.

cli/pkg/github/github.go

@@ -276,16 +276,14 @@ func GitHubCI(lock core_locking.Lock, policyCheckerProvider core_policy.PolicyCh
 		jobs = digger.SortedCommandsByDependency(jobs, &dependencyGraph)
 
 		allAppliesSuccessful, atLeastOneApply, err := digger.RunJobs(jobs, &githubPrService, &githubPrService, lock, reporter, planStorage, policyChecker, comment_updater.NoopCommentUpdater{}, backendApi, "", false, false, "0", currentDir)
-		if err != nil {
-			usage.ReportErrorAndExit(githubActor, fmt.Sprintf("Failed to run commands. %s", err), 8)
+		if !allAppliesSuccessful || err != nil {
 			// aggregate status checks: failure
-			if allAppliesSuccessful {
-				if atLeastOneApply {
-					githubPrService.SetStatus(prNumber, "failure", "digger/apply")
-				} else {
-					githubPrService.SetStatus(prNumber, "failure", "digger/plan")
-				}
+			if scheduler.IsPlanJobs(jobs) {
+				githubPrService.SetStatus(prNumber, "failure", "digger/plan")
+			} else {
+				githubPrService.SetStatus(prNumber, "failure", "digger/apply")
 			}
+			usage.ReportErrorAndExit(githubActor, fmt.Sprintf("Failed to run commands. %s", err), 8)
 		}
 
 		if diggerConfig.AutoMerge && allAppliesSuccessful && atLeastOneApply && coversAllImpactedProjects {
@@ -295,10 +293,10 @@ func GitHubCI(lock core_locking.Lock, policyCheckerProvider core_policy.PolicyCh
 
 		if allAppliesSuccessful {
 			// aggreate status checks: success
-			if atLeastOneApply {
-				githubPrService.SetStatus(prNumber, "success", "digger/apply")
-			} else {
+			if scheduler.IsPlanJobs(jobs) {
 				githubPrService.SetStatus(prNumber, "success", "digger/plan")
+			} else {
+				githubPrService.SetStatus(prNumber, "success", "digger/apply")
 			}
 		}