Split reconcile into prepare and reconcile

The current "reconcile" function does a lot of things, which means
it's hard to test properly, it's hard to follow the logic and
it's hard to handle all possible errors and events properly.

This splits reconcile into two parts, the first one that deals
preparing and validating the taskrun and all the resources it
depends on, the second one that actually reconciles the TaskRun
by creating the pod if required and updating the TaskRun from
the pod.

This adds events that were missing for error situations that
happen during preparation and validation.

pkg/pod/status.go

@@ -63,6 +63,10 @@ const (
 	// config error of container
 	ReasonCreateContainerConfigError = "CreateContainerConfigError"
 
+	// ReasonPodCreationFailed indicates that the reason for the current condition
+	// is that the creation of the pod backing the TaskRun failed
+	ReasonPodCreationFailed = "PodCreationFailed"
+
 	// ReasonSucceeded indicates that the reason for the finished status is that all of the steps
 	// completed successfully
 	ReasonSucceeded = "Succeeded"

pkg/reconciler/event.go

@@ -27,10 +27,10 @@ import (
 func EmitEvent(c record.EventRecorder, beforeCondition *apis.Condition, afterCondition *apis.Condition, object runtime.Object) {
 	if beforeCondition != afterCondition && afterCondition != nil {
 		// Create events when the obj result is in.
-		if afterCondition.Status == corev1.ConditionTrue {
-			c.Event(object, corev1.EventTypeNormal, "Succeeded", afterCondition.Message)
+		if afterCondition.Status == corev1.ConditionTrue || afterCondition.Status == corev1.ConditionUnknown {
+			c.Event(object, corev1.EventTypeNormal, afterCondition.Reason, afterCondition.Message)
 		} else if afterCondition.Status == corev1.ConditionFalse {
-			c.Event(object, corev1.EventTypeWarning, "Failed", afterCondition.Message)
+			c.Event(object, corev1.EventTypeWarning, afterCondition.Reason, afterCondition.Message)
 		}
 	}
 }

pkg/reconciler/taskrun/taskrun.go

@@ -79,9 +79,6 @@ var _ controller.Reconciler = (*Reconciler)(nil)
 // converge the two. It then updates the Status block of the Task Run
 // resource with the current status of the resource.
 func (c *Reconciler) Reconcile(ctx context.Context, key string) error {
-	// In case of reconcile errors, we store the error in a multierror, attempt
-	// to update, and return the original error combined with any update error
-	var merr error
 
 	// Convert the namespace/name string into a distinct namespace and name
 	namespace, name, err := cache.SplitMetaNamespaceKey(key)
@@ -182,38 +179,60 @@ func (c *Reconciler) Reconcile(ctx context.Context, key string) error {
 		return multierror.Append(err, c.updateStatusLabelsAndAnnotations(tr, original)).ErrorOrNil()
 	}
 
+	// prepare fetches all required resources, validates them together with the
+	// taskrun, runs API convertions. Errors that come out of prepare are
+	// permanent one, so in case of error we update, emit events and return
+	taskSpec, rtr, err := c.prepare(ctx, tr)
+	if err != nil {
+		c.Logger.Errorf("TaskRun prepare error: %v", err.Error())
+		after := tr.Status.GetCondition(apis.ConditionSucceeded)
+		reconciler.EmitEvent(c.Recorder, nil, after, tr)
+		// We only return an error if update failed, otherwise we don't want to
+		// reconcile an invalid TaskRun anymore
+		return c.updateStatusLabelsAndAnnotations(tr, original)
+	}
+
+	// Store the condition before reconcile
+	before := tr.Status.GetCondition(apis.ConditionSucceeded)
+
 	// Reconcile this copy of the task run and then write back any status
 	// updates regardless of whether the reconciliation errored out.
-	if err := c.reconcile(ctx, tr); err != nil {
+	if err = c.reconcile(ctx, tr, taskSpec, rtr); err != nil {
 		c.Logger.Errorf("Reconcile error: %v", err.Error())
-		merr = multierror.Append(merr, err)
 	}
-	return multierror.Append(merr, c.updateStatusLabelsAndAnnotations(tr, original)).ErrorOrNil()
+
+	// Emit events (only when ConditionSucceeded was changed)
+	after := tr.Status.GetCondition(apis.ConditionSucceeded)
+	reconciler.EmitEvent(c.Recorder, before, after, tr)
+
+	return multierror.Append(err, c.updateStatusLabelsAndAnnotations(tr, original)).ErrorOrNil()
 }
 
-func (c *Reconciler) reconcile(ctx context.Context, tr *v1alpha1.TaskRun) error {
+// TODO(afrittoli) for now we return spec and resources. In future we should store
+// them in the TaskRun.Status so we don't need to re-run `prepare` at every
+// reconcile.
+func (c *Reconciler) prepare(ctx context.Context, tr *v1alpha1.TaskRun) (*v1alpha1.TaskSpec, *resources.ResolvedTaskResources, error) {
 	// We may be reading a version of the object that was stored at an older version
 	// and may not have had all of the assumed default specified.
 	tr.SetDefaults(contexts.WithUpgradeViaDefaulting(ctx))
 
 	if err := tr.ConvertTo(ctx, &v1beta1.TaskRun{}); err != nil {
 		if ce, ok := err.(*v1beta1.CannotConvertError); ok {
 			tr.Status.MarkResourceNotConvertible(ce)
-			return nil
+			return nil, nil, nil
 		}
-		return err
+		return nil, nil, err
 	}
 
 	getTaskFunc, kind := c.getTaskFunc(tr)
 	taskMeta, taskSpec, err := resources.GetTaskData(ctx, tr, getTaskFunc)
 	if err != nil {
 		if ce, ok := err.(*v1beta1.CannotConvertError); ok {
 			tr.Status.MarkResourceNotConvertible(ce)
-			return nil
 		}
 		c.Logger.Errorf("Failed to determine Task spec to use for taskrun %s: %v", tr.Name, err)
 		tr.Status.MarkResourceFailed(podconvert.ReasonFailedResolution, err)
-		return nil
+		return nil, nil, err
 	}
 
 	// Propagate labels from Task to TaskRun.
@@ -249,19 +268,19 @@ func (c *Reconciler) reconcile(ctx context.Context, tr *v1alpha1.TaskRun) error
 	if err != nil {
 		c.Logger.Errorf("Failed to resolve references for taskrun %s: %v", tr.Name, err)
 		tr.Status.MarkResourceFailed(podconvert.ReasonFailedResolution, err)
-		return nil
+		return nil, nil, err
 	}
 
 	if err := ValidateResolvedTaskResources(tr.Spec.Params, rtr); err != nil {
 		c.Logger.Errorf("TaskRun %q resources are invalid: %v", tr.Name, err)
 		tr.Status.MarkResourceFailed(podconvert.ReasonFailedValidation, err)
-		return nil
+		return nil, nil, err
 	}
 
 	if err := workspace.ValidateBindings(taskSpec.Workspaces, tr.Spec.Workspaces); err != nil {
 		c.Logger.Errorf("TaskRun %q workspaces are invalid: %v", tr.Name, err)
 		tr.Status.MarkResourceFailed(podconvert.ReasonFailedValidation, err)
-		return nil
+		return nil, nil, err
 	}
 
 	// Initialize the cloud events if at least a CloudEventResource is defined
@@ -275,8 +294,15 @@ func (c *Reconciler) reconcile(ctx context.Context, tr *v1alpha1.TaskRun) error
 	}
 	cloudevent.InitializeCloudEvents(tr, prs)
 
+	return taskSpec, rtr, nil
+}
+
+func (c *Reconciler) reconcile(ctx context.Context, tr *v1alpha1.TaskRun,
+	taskSpec *v1alpha1.TaskSpec, rtr *resources.ResolvedTaskResources) error {
 	// Get the TaskRun's Pod if it should have one. Otherwise, create the Pod.
 	var pod *corev1.Pod
+	var err error
+
 	if tr.Status.PodName != "" {
 		pod, err = c.KubeClientSet.CoreV1().Pods(tr.Namespace).Get(tr.Status.PodName, metav1.GetOptions{})
 		if k8serrors.IsNotFound(err) {
@@ -303,7 +329,7 @@ func (c *Reconciler) reconcile(ctx context.Context, tr *v1alpha1.TaskRun) error
 
 	if pod == nil {
 		if tr.HasVolumeClaimTemplate() {
-			if err = c.pvcHandler.CreatePersistentVolumeClaimsForWorkspaces(tr.Spec.Workspaces, tr.GetOwnerReference(), tr.Namespace); err != nil {
+			if err := c.pvcHandler.CreatePersistentVolumeClaimsForWorkspaces(tr.Spec.Workspaces, tr.GetOwnerReference(), tr.Namespace); err != nil {
 				c.Logger.Errorf("Failed to create PVC for TaskRun %s: %v", tr.Name, err)
 				tr.Status.MarkResourceFailed(volumeclaim.ReasonCouldntCreateWorkspacePVC,
 					fmt.Errorf("Failed to create PVC for TaskRun %s workspaces correctly: %s",
@@ -312,6 +338,7 @@ func (c *Reconciler) reconcile(ctx context.Context, tr *v1alpha1.TaskRun) error
 			}
 
 			taskRunWorkspaces := applyVolumeClaimTemplates(tr.Spec.Workspaces, tr.GetOwnerReference())
+			// This is used by createPod below. Changes to the Spec are not updated.
 			tr.Spec.Workspaces = taskRunWorkspaces
 		}
 
@@ -337,19 +364,14 @@ func (c *Reconciler) reconcile(ctx context.Context, tr *v1alpha1.TaskRun) error
 		}
 	}
 
-	before := tr.Status.GetCondition(apis.ConditionSucceeded)
-
 	// Convert the Pod's status to the equivalent TaskRun Status.
 	tr.Status = podconvert.MakeTaskRunStatus(c.Logger, *tr, pod, *taskSpec)
 
 	if err := updateTaskRunResourceResult(tr, pod.Status); err != nil {
 		return err
 	}
 
-	after := tr.Status.GetCondition(apis.ConditionSucceeded)
-
-	reconciler.EmitEvent(c.Recorder, before, after, tr)
-	c.Logger.Infof("Successfully reconciled taskrun %s/%s with status: %#v", tr.Name, tr.Namespace, after)
+	c.Logger.Infof("Successfully reconciled taskrun %s/%s with status: %#v", tr.Name, tr.Namespace, tr.Status.GetCondition(apis.ConditionSucceeded))
 
 	return nil
 }
@@ -445,33 +467,31 @@ func (c *Reconciler) getTaskFunc(tr *v1alpha1.TaskRun) (resources.GetTask, v1alp
 }
 
 func (c *Reconciler) handlePodCreationError(tr *v1alpha1.TaskRun, err error) {
-	var reason, msg string
-	var succeededStatus corev1.ConditionStatus
+	var msg string
 	if isExceededResourceQuotaError(err) {
-		succeededStatus = corev1.ConditionUnknown
-		reason = podconvert.ReasonExceededResourceQuota
 		backoff, currentlyBackingOff := c.timeoutHandler.GetBackoff(tr)
 		if !currentlyBackingOff {
 			go c.timeoutHandler.SetTaskRunTimer(tr, time.Until(backoff.NextAttempt))
 		}
 		msg = fmt.Sprintf("TaskRun Pod exceeded available resources, reattempted %d times", backoff.NumAttempts)
+		tr.Status.SetCondition(&apis.Condition{
+			Type:    apis.ConditionSucceeded,
+			Status:  corev1.ConditionUnknown,
+			Reason:  podconvert.ReasonExceededResourceQuota,
+			Message: fmt.Sprintf("%s: %v", msg, err),
+		})
 	} else {
-		succeededStatus = corev1.ConditionFalse
-		reason = podconvert.ReasonCouldntGetTask
+		// The pod creation failed, not because of quota issues. The most likely
+		// reason is that something is wrong with the spec of the Task
+		msg = fmt.Sprintf("failed to create task run pod %q: %v. Maybe ", tr.Name, err)
 		if tr.Spec.TaskRef != nil {
-			msg = fmt.Sprintf("Missing or invalid Task %s/%s", tr.Namespace, tr.Spec.TaskRef.Name)
+			msg += fmt.Sprintf("missing or invalid Task %s/%s", tr.Namespace, tr.Spec.TaskRef.Name)
 		} else {
-			msg = "Invalid TaskSpec"
+			msg += "invalid TaskSpec"
 		}
+		tr.Status.MarkResourceFailed(podconvert.ReasonCouldntGetTask, errors.New(msg))
 	}
-	tr.Status.SetCondition(&apis.Condition{
-		Type:    apis.ConditionSucceeded,
-		Status:  succeededStatus,
-		Reason:  reason,
-		Message: fmt.Sprintf("%s: %v", msg, err),
-	})
-	c.Recorder.Eventf(tr, corev1.EventTypeWarning, "BuildCreationFailed", "Failed to create build pod %q: %v", tr.Name, err)
-	c.Logger.Errorf("Failed to create build pod for task %q: %v", tr.Name, err)
+	c.Logger.Error("Failed to create task run pod for task %q: %v", tr.Name, err)
 }
 
 // failTaskRun stops a TaskRun with the provided Reason

pkg/reconciler/taskrun/taskrun_test.go

@@ -1219,7 +1219,7 @@ func TestReconcilePodFetchError(t *testing.T) {
 	})
 
 	if err := c.Reconciler.Reconcile(context.Background(), getRunName(taskRun)); err == nil {
-		t.Fatal("expected error when reconciling a Task for which we couldn't get the corresponding Build Pod but got nil")
+		t.Fatal("expected error when reconciling a Task for which we couldn't get the corresponding Pod but got nil")
 	}
 }