enhance: report a GitHub-style "Set up job" section (#1089)

Reshapes the job log's "Set up job" section to mirror `actions/runner`:

- runner name/version, then `Runner Information` (labels, task, job, repository, event) and `Operating System` groups
- every required action downloaded up front under `Prepare all required actions`, each as `Download action repository '<action>@<ref>' (SHA:<sha>)`
- `Complete job name` closes the section

Downloading up front is the one behavioral change: the same set was already fetched during the pre stage regardless of a step's `if`, now just before the first pre step, so a download failure is reported against the job rather than a step.

---------

Co-authored-by: silverwind <me@silverwind.io>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1089
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>

act/runner/job_executor.go

@@ -71,9 +71,67 @@ func reportStepError(ctx context.Context, rc *RunContext, err error) {
 	rc.markFailed()
 }
 
+// actionPreparer is implemented by steps that download an action before they run, so the job
+// executor can fetch all of them up front.
+type actionPreparer interface {
+	prepareActionExecutor() common.Executor
+	actionDownloadInfo() (reference, sha string, ok bool)
+}
+
+// printPrepareActions downloads every action the job uses before its first step runs and reports
+// them as actions/runner's "Prepare all required actions" section does. The steps still call
+// prepareActionExecutor themselves; it is a no-op once the action is resolved here.
+func printPrepareActions(rc *RunContext, preparers []actionPreparer) common.Executor {
+	return func(ctx context.Context) error {
+		if len(preparers) == 0 {
+			return nil
+		}
+
+		rawLogger := common.Logger(ctx).WithField(rawOutputField, true)
+		rawLogger.Infof("Prepare all required actions")
+
+		for _, preparer := range preparers {
+			if err := preparer.prepareActionExecutor()(ctx); err != nil {
+				// No step has run yet, so the failure belongs to the job.
+				reportStepError(ctx, rc, err)
+				return err
+			}
+			reference, sha, ok := preparer.actionDownloadInfo()
+			if !ok {
+				continue
+			}
+			if sha == "" {
+				rawLogger.Infof("Download action repository '%s'", reference)
+			} else {
+				rawLogger.Infof("Download action repository '%s' (SHA:%s)", reference, sha)
+			}
+		}
+		return nil
+	}
+}
+
+// printCompleteJobName closes the setup section the way actions/runner ends its "Set up job" step.
+func printCompleteJobName(rc *RunContext) common.Executor {
+	return func(ctx context.Context) error {
+		// Name holds a matrix combination; JobName is the shared name GitHub reports.
+		name := rc.JobName
+		if name == "" {
+			name = rc.Name
+		}
+		if name == "" && rc.Run != nil {
+			name = rc.Run.JobID
+		}
+		common.Logger(ctx).WithField(rawOutputField, true).Infof("Complete job name: %s", name)
+		return nil
+	}
+}
+
 func newJobExecutor(info jobInfo, sf stepFactory, rc *RunContext) common.Executor {
 	steps := make([]common.Executor, 0)
 	preSteps := make([]common.Executor, 0)
+	// Collected separately: every action is downloaded before the first pre step runs.
+	stepPreSteps := make([]common.Executor, 0)
+	preparers := make([]actionPreparer, 0)
 	var postExecutor common.Executor
 
 	steps = append(steps, func(ctx context.Context) error {
@@ -120,9 +178,13 @@ func newJobExecutor(info jobInfo, sf stepFactory, rc *RunContext) common.Executo
 			return common.NewErrorExecutor(err)
 		}
 
+		if preparer, ok := step.(actionPreparer); ok {
+			preparers = append(preparers, preparer)
+		}
+
 		stepIdx := stepModel.Number
 		preExec := step.pre()
-		preSteps = append(preSteps, useStepLogger(rc, stepModel, stepStagePre, func(ctx context.Context) error {
+		stepPreSteps = append(stepPreSteps, useStepLogger(rc, stepModel, stepStagePre, func(ctx context.Context) error {
 			rc.CurrentStepIndex = stepIdx
 			preErr := preExec(ctx)
 			if preErr != nil {
@@ -164,6 +226,11 @@ func newJobExecutor(info jobInfo, sf stepFactory, rc *RunContext) common.Executo
 		}
 	}
 
+	// The setup section of the job log: download the actions, run the pre steps, then name the job.
+	preSteps = append(preSteps, printPrepareActions(rc, preparers))
+	preSteps = append(preSteps, stepPreSteps...)
+	preSteps = append(preSteps, printCompleteJobName(rc))
+
 	postExecutor = postExecutor.Finally(func(ctx context.Context) error {
 		jobError := common.JobError(ctx)
 		var err error