Promoting onError to beta

Pipeline 0.27 was released in August 2021 which introduced an alpha feature to
specify onError in a step. This feature was implemented in the PR #4106:
#4106

To enable this feature, the Tekton Pipeline deployment had to set
enable-api-fields to alpha.

After discussing this in the API WG:
https://docs.google.com/document/d/17PodAxG8hV351fBhSu7Y_OIPhGTVgj6OJ2lPphYYRpU/edit#heading=h.ig94pf1w10xc
We have sent an email out to collect the feedback from the users.  @skaegi is
looking forward to this promotion.

This commit is updating task validation to no longer require enable-api-fields
is set to alpha.
The documentation is updated to moved it out of the alpha section.
The example yamls moved out of alpha.
Updated e2e to not include alpha flag.

docs/install.md

@@ -399,7 +399,6 @@ Features currently in "alpha" are:
 | [Hermetic Execution Mode](./hermetic.md)                                        | [TEP-0025](https://github.com/tektoncd/community/blob/main/teps/0025-hermekton.md)                          | [v0.25.0](https://github.com/tektoncd/pipeline/releases/tag/v0.25.0) |                             |
 | [Graceful Termination](./pipelineruns.md#gracefully-cancelling-a-pipelinerun)   | [TEP-0058](https://github.com/tektoncd/community/blob/main/teps/0058-graceful-pipeline-run-termination.md)  | [v0.25.0](https://github.com/tektoncd/pipeline/releases/tag/v0.25.0) |                             |
 | [`PipelineRun` Timeouts](./pipelineruns.md#configuring-a-failure-timeout)       | [TEP-0046](https://github.com/tektoncd/community/blob/main/teps/0046-finallytask-execution-post-timeout.md) | [v0.25.0](https://github.com/tektoncd/pipeline/releases/tag/v0.25.0) |                             |
-| [Specifying `onError` for a `Step`](./tasks.md#specifying-onerror-for-a-step)   | [TEP-0040](https://github.com/tektoncd/community/blob/main/teps/0040-ignore-step-errors.md)                 | [v0.27.0](https://github.com/tektoncd/pipeline/releases/tag/v0.27.0) |                             |
 | [Implicit `Parameters`](./taskruns.md#implicit-parameters)                      | [TEP-0023](https://github.com/tektoncd/community/blob/main/teps/0023-implicit-mapping.md)                   | [v0.28.0](https://github.com/tektoncd/pipeline/releases/tag/v0.28.0) |                             |
 | [Windows Scrips](./tasks.md#windows-scripts)                                    | [TEP-0057](https://github.com/tektoncd/community/blob/main/teps/0057-windows-support.md)                    | [v0.28.0](https://github.com/tektoncd/pipeline/releases/tag/v0.28.0) |                             |
 

docs/tasks.md

@@ -335,9 +335,6 @@ steps:
 
 #### Specifying `onError` for a `step`
 
-This is an alpha feature. The `enable-api-fields` feature flag [must be set to `"alpha"`](./install.md)
-to specify `onError` for a `step`.
-
 When a `step` in a `task` results in a failure, the rest of the steps in the `task` are skipped and the `taskRun` is
 declared a failure. If you would like to ignore such step errors and continue executing the rest of the steps in
 the task, you can specify `onError` for such a `step`.
@@ -386,8 +383,8 @@ kubectl get tr taskrun-unit-test-t6qcl -o json | jq .status
   ],
 ```
 
-For an end-to-end example, see [the taskRun ignoring a step error](../examples/v1beta1/taskruns/alpha/ignore-step-error.yaml)
-and [the pipelineRun ignoring a step error](../examples/v1beta1/pipelineruns/alpha/ignore-step-error.yaml).
+For an end-to-end example, see [the taskRun ignoring a step error](../examples/v1beta1/taskruns/ignore-step-error.yaml)
+and [the pipelineRun ignoring a step error](../examples/v1beta1/pipelineruns/ignore-step-error.yaml).
 
 #### Accessing Step's `exitCode` in subsequent `Steps`
 

pkg/apis/pipeline/v1beta1/task_validation.go

@@ -222,7 +222,6 @@ func validateStep(ctx context.Context, s Step, names sets.String) (errs *apis.Fi
 	}
 
 	if s.OnError != "" {
-		errs = errs.Also(ValidateEnabledAPIFields(ctx, "step onError", config.AlphaAPIFields).ViaField("steps"))
 		if s.OnError != "continue" && s.OnError != "stopAndFail" {
 			errs = errs.Also(&apis.FieldError{
 				Message: fmt.Sprintf("invalid value: %v", s.OnError),

pkg/apis/pipeline/v1beta1/task_validation_test.go

@@ -1178,13 +1178,7 @@ func TestStepOnError(t *testing.T) {
 			ts := &v1beta1.TaskSpec{
 				Steps: tt.steps,
 			}
-			featureFlags, _ := config.NewFeatureFlagsFromMap(map[string]string{
-				"enable-api-fields": "alpha",
-			})
-			cfg := &config.Config{
-				FeatureFlags: featureFlags,
-			}
-			ctx := config.ToContext(context.Background(), cfg)
+			ctx := context.Background()
 			ts.SetDefaults(ctx)
 			err := ts.Validate(ctx)
 			if tt.expectedError == nil && err != nil {
@@ -1241,18 +1235,6 @@ func TestIncompatibleAPIVersions(t *testing.T) {
 				}},
 			}},
 		},
-	}, {
-		name:            "step onError requires alpha",
-		requiredVersion: "alpha",
-		spec: v1beta1.TaskSpec{
-			Steps: []v1beta1.Step{{
-				OnError: "continue",
-				Container: corev1.Container{
-					Image: "image",
-					Args:  []string{"arg"},
-				},
-			}},
-		},
 	}, {
 		name:            "windows script support requires alpha",
 		requiredVersion: "alpha",

test/ignore_step_error_test.go

@@ -31,7 +31,7 @@ func TestMissingResultWhenStepErrorIsIgnored(t *testing.T) {
 	ctx := context.Background()
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
-	c, namespace := setup(ctx, t, requireAlphaFeatureFlags)
+	c, namespace := setup(ctx, t)
 	knativetest.CleanupOnInterrupt(func() { tearDown(ctx, t, c, namespace) }, t.Logf)
 	defer tearDown(ctx, t, c, namespace)