TEP-0059: Remove scope-when-expressions-to-task feature flag

In [TEP-0007: Conditions Beta][tep-0007], we introduced `when` expressions to guard
execution of `Tasks` in `Pipelines`. To align with `Conditions`, we set scope of
`when` expressions to the guarded `Task` and its dependent `Tasks`.

In [TEP-0059: Skipping Strategies][tep-0059], we proposed changing the scope of
`when` expressions to the guarded `Task` only. This was implemented in #4085.
We provided a feature flag, `scope-when-expressions-to-task`, to support migration.
It defaulted to `false` for 9 months per our [Beta API compatibility policy][policy],
meaning that we continued to guard the `Task` and its dependent `Tasks`. Then in #4580,
we flipped the flag to `true` to guard the `Task` only by default.

In this change, we remove the `scope-when-expressions-to-task` flag and complete the
migration.

Closes #4461.

[tep-0007]: https:/tektoncd/community/blob/main/teps/0007-conditions-beta.md
[tep-0059]: https:/tektoncd/community/blob/main/teps/0059-skipping-strategies.md
[policy]: https:/tektoncd/pipeline/blob/main/api_compatibility_policy.md

config/config-feature-flags.yaml

@@ -70,10 +70,6 @@ data:
  # Setting this flag will determine which gated features are enabled.
  # Acceptable values are "stable" or "alpha".
  enable-api-fields: "stable"
- # Setting this flag to "false" scopes when expressions to guard a Task and
- # its dependent Tasks. This flag defaults to "true"; when expressions guard
- # the Task only. See TEP-0059 and Pipeline documentation for more details.
- scope-when-expressions-to-task: "true"
  # Setting this flag to "true" enables CloudEvents for Runs, as long as a
  # CloudEvents sink is configured in the config-defaults config map
  send-cloudevents-for-runs: "false"

docs/deprecations.md

@@ -23,5 +23,4 @@ being deprecated.
 | [The `PipelineRun.Spec.ServiceAccountNames` field is deprecated and will be removed.](https:/tektoncd/pipeline/issues/2614) | [v0.15.0](https:/tektoncd/pipeline/releases/tag/v0.15.0) | Beta | May 15 2021 |
 | [`Conditions` CRD is deprecated and will be removed. Use `when` expressions instead.](https:/tektoncd/community/blob/main/teps/0007-conditions-beta.md) | [v0.16.0](https:/tektoncd/pipeline/releases/tag/v0.16.0) | Alpha | Nov 02 2020 |
 | [`PipelineRunCancelled` is deprecated and will be removed](https:/tektoncd/pipeline/issues/4611) | [v0.25.0](https:/tektoncd/pipeline/releases/tag/v0.25.0) | Beta | March 15 2022 |
-| [The `scope-when-expressions-to-task` flag will be removed](https:/tektoncd/pipeline/issues/4461) | [v0.27.0](https:/tektoncd/pipeline/releases/tag/v0.27.0) | Beta | March 10 2022 |
 | [`PipelineResources` are deprecated.](https:/tektoncd/community/blob/main/teps/0074-deprecate-pipelineresources.md) | [v0.30.0](https:/tektoncd/pipeline/releases/tag/v0.30.0) | Alpha | Dec 20 2021 |

docs/install.md

@@ -386,10 +386,6 @@ use of custom tasks in pipelines.
 most stable features to be used. Set it to "alpha" to allow [alpha
 features](#alpha-features) to be used.
 
-- `scope-when-expressions-to-task`: set this flag to "true" to scope `when` expressions to guard a `Task` only. Set it
- to "false" to guard a `Task` and its dependent `Tasks`. It defaults to "true". For more information, see [guarding
- `Task` execution using `when` expressions](pipelines.md#guard-task-execution-using-whenexpressions).
-
 - `embedded-status`: set this flag to "full" to enable full embedding of `TaskRun` and `Run` statuses in the 
  `PipelineRun` status. Set it to "minimal" to populate the `ChildReferences` field in the `PipelineRun` status with
  name, kind, and API version information for each `TaskRun` and `Run` in the `PipelineRun` instead. Set it to "both" to 

docs/pipelines.md

@@ -578,25 +578,6 @@ There are a lot of scenarios where `when` expressions can be really useful. Some
 
 #### Guarding a `Task` and its dependent `Tasks`
 
-> :warning: **Scoping `when` expressions to a `Task` and its dependent `Tasks` is deprecated.**
->
-> Consider migrating to scoping `when` expressions to the guarded `Task` only instead.
-> Read more in the [documentation](#guarding-a-task-only) and [TEP-0059: Skipping Strategies][tep-0059].
-> 
-[tep-0059]: https:/tektoncd/community/blob/main/teps/0059-skipping-strategies.md
-
-To guard a `Task` and its dependent `Tasks`, set the global default scope of `when` expressions to `Task` using the
-`scope-when-expressions-to-task` field in [`config/config-feature-flags.yaml`](install.md#customizing-the-pipelines-controller-behavior)
-by changing it to "false".
-
-When `when` expressions evaluate to `False`, and `scope-when-expressions-to-task` is set to "false", the `Task` and 
-its dependent `Tasks` will be skipped while the rest of the `Pipeline` will execute. Dependencies between `Tasks` can
-be either ordering ([`runAfter`](https:/tektoncd/pipeline/blob/main/docs/pipelines.md#using-the-runafter-parameter))
-or resource (e.g. [`Results`](https:/tektoncd/pipeline/blob/main/docs/pipelines.md#using-results))
-dependencies, as further described in [configuring execution order](#configuring-the-task-execution-order). The global
-default scope of `when` expressions is set to a `Task` only; `scope-when-expressions-to-task` field in 
-[`config/config-feature-flags.yaml`](install.md#customizing-the-pipelines-controller-behavior) defaults to "true".
-
 To guard a `Task` and its dependent Tasks:
 - cascade the `when` expressions to the specific dependent `Tasks` to be guarded as well
 - compose the `Task` and its dependent `Tasks` as a unit to be guarded and executed together using `Pipelines` in `Pipelines`
@@ -798,8 +779,8 @@ tasks:
  name: slack-msg
 ```
 
-With `when` expressions scoped to `Task`, if `manual-approval` is skipped, execution of its dependent `Tasks` 
-(`slack-msg`, `build-image` and `deploy-image`) would be unblocked regardless:
+If `manual-approval` is skipped, execution of its dependent `Tasks` (`slack-msg`, `build-image` and `deploy-image`) 
+would be unblocked regardless:
 - `build-image` and `deploy-image` should be executed successfully
 - `slack-msg` will be skipped because it is missing the `approver` `Result` from `manual-approval`
  - dependents of `slack-msg` would have been skipped too if it had any of them

pkg/apis/config/feature_flags.go

@@ -51,8 +51,6 @@ const (
  DefaultEnableTektonOciBundles = false
  // DefaultEnableCustomTasks is the default value for "enable-custom-tasks".
  DefaultEnableCustomTasks = false
- // DefaultScopeWhenExpressionsToTask is the default value for "scope-when-expressions-to-task".
- DefaultScopeWhenExpressionsToTask = true
  // DefaultEnableAPIFields is the default value for "enable-api-fields".
  DefaultEnableAPIFields = StableAPIFields
  // DefaultSendCloudEventsForRuns is the default value for "send-cloudevents-for-runs".
@@ -67,7 +65,6 @@ const (
  enableTektonOCIBundles = "enable-tekton-oci-bundles"
  enableCustomTasks = "enable-custom-tasks"
  enableAPIFields = "enable-api-fields"
- scopeWhenExpressionsToTask = "scope-when-expressions-to-task"
  sendCloudEventsForRuns = "send-cloudevents-for-runs"
  embeddedStatus = "embedded-status"
 )
@@ -124,9 +121,6 @@ func NewFeatureFlagsFromMap(cfgMap map[string]string) (*FeatureFlags, error) {
  if err := setFeature(requireGitSSHSecretKnownHostsKey, DefaultRequireGitSSHSecretKnownHosts, &tc.RequireGitSSHSecretKnownHosts); err != nil {
  return nil, err
  }
- if err := setFeature(scopeWhenExpressionsToTask, DefaultScopeWhenExpressionsToTask, &tc.ScopeWhenExpressionsToTask); err != nil {
- return nil, err
- }
  if err := setEnabledAPIFields(cfgMap, DefaultEnableAPIFields, &tc.EnableAPIFields); err != nil {
  return nil, err
  }

pkg/apis/config/feature_flags_test.go

@@ -36,7 +36,6 @@ func TestNewFeatureFlagsFromConfigMap(t *testing.T) {
  {
  expectedConfig: &config.FeatureFlags{
  RunningInEnvWithInjectedSidecars: config.DefaultRunningInEnvWithInjectedSidecars,
- ScopeWhenExpressionsToTask: config.DefaultScopeWhenExpressionsToTask,
  EnableAPIFields: "stable",
  EmbeddedStatus: config.DefaultEmbeddedStatus,
  },
@@ -49,7 +48,6 @@ func TestNewFeatureFlagsFromConfigMap(t *testing.T) {
  RequireGitSSHSecretKnownHosts: true,
  EnableTektonOCIBundles: true,
  EnableCustomTasks: true,
- ScopeWhenExpressionsToTask: true,
  EnableAPIFields: "alpha",
  SendCloudEventsForRuns: true,
  EmbeddedStatus: "both",
@@ -65,7 +63,6 @@ func TestNewFeatureFlagsFromConfigMap(t *testing.T) {
  EnableCustomTasks: true,
 
  RunningInEnvWithInjectedSidecars: config.DefaultRunningInEnvWithInjectedSidecars,
- ScopeWhenExpressionsToTask: config.DefaultScopeWhenExpressionsToTask,
  EmbeddedStatus: config.DefaultEmbeddedStatus,
  },
  fileName: "feature-flags-enable-api-fields-overrides-bundles-and-custom-tasks",
@@ -77,7 +74,6 @@ func TestNewFeatureFlagsFromConfigMap(t *testing.T) {
  EnableCustomTasks: true,
 
  RunningInEnvWithInjectedSidecars: config.DefaultRunningInEnvWithInjectedSidecars,
- ScopeWhenExpressionsToTask: config.DefaultScopeWhenExpressionsToTask,
  EmbeddedStatus: config.DefaultEmbeddedStatus,
  },
  fileName: "feature-flags-bundles-and-custom-tasks",
@@ -97,7 +93,6 @@ func TestNewFeatureFlagsFromEmptyConfigMap(t *testing.T) {
  FeatureFlagsConfigEmptyName := "feature-flags-empty"
  expectedConfig := &config.FeatureFlags{
  RunningInEnvWithInjectedSidecars: true,
- ScopeWhenExpressionsToTask: config.DefaultScopeWhenExpressionsToTask,
  EnableAPIFields: "stable",
  EmbeddedStatus: config.DefaultEmbeddedStatus,
  }
@@ -144,8 +139,6 @@ func TestNewFeatureFlagsConfigMapErrors(t *testing.T) {
  fileName: "feature-flags-invalid-enable-api-fields",
  }, {
  fileName: "feature-flags-invalid-embedded-status",
- }, {
- fileName: "feature-flags-invalid-scope-when-expressions-to-task",
  }} {
  t.Run(tc.fileName, func(t *testing.T) {
  cm := test.ConfigMapFromTestFile(t, tc.fileName)

pkg/apis/config/testdata/feature-flags-all-flags-set.yaml

@@ -23,7 +23,6 @@ data:
  require-git-ssh-secret-known-hosts: "true"
  enable-tekton-oci-bundles: "true"
  enable-custom-tasks: "true"
- scope-when-expressions-to-task: "true"
  enable-api-fields: "alpha"
  send-cloudevents-for-runs: "true"
  embedded-status: "both"

pkg/reconciler/pipelinerun/pipelinerun.go

@@ -462,11 +462,10 @@ func (c *Reconciler) reconcile(ctx context.Context, pr *v1beta1.PipelineRun, get
  // Build PipelineRunFacts with a list of resolved pipeline tasks,
  // dag tasks graph and final tasks graph
  pipelineRunFacts := &resources.PipelineRunFacts{
- State: pipelineRunState,
- SpecStatus: pr.Spec.Status,
- TasksGraph: d,
- FinalTasksGraph: dfinally,
- ScopeWhenExpressionsToTask: config.FromContextOrDefaults(ctx).FeatureFlags.ScopeWhenExpressionsToTask,
+ State: pipelineRunState,
+ SpecStatus: pr.Spec.Status,
+ TasksGraph: d,
+ FinalTasksGraph: dfinally,
  }
 
  for _, rprt := range pipelineRunFacts.State {

pkg/reconciler/pipelinerun/pipelinerun_test.go

@@ -4878,7 +4878,7 @@ func TestReconcileWithWhenExpressionsWithTaskResults(t *testing.T) {
  }
 }
 
-func TestReconcileWithWhenExpressionsScopedToTask(t *testing.T) {
+func TestReconcileWithWhenExpressions(t *testing.T) {
  // (b)
  // /
  // (a) ———— (c) ———— (d)
@@ -4977,21 +4977,10 @@ func TestReconcileWithWhenExpressionsScopedToTask(t *testing.T) {
  {ObjectMeta: baseObjectMeta("f-task", "foo")},
  }
 
- // set the scope of when expressions to task -- execution of dependent tasks is unblocked
- cms := []*corev1.ConfigMap{
- {
- ObjectMeta: metav1.ObjectMeta{Name: config.GetFeatureFlagsConfigName(), Namespace: system.Namespace()},
- Data: map[string]string{
- "scope-when-expressions-to-task": "true",
- },
- },
- }
-
  d := test.Data{
  PipelineRuns: prs,
  Pipelines: ps,
  Tasks: ts,
- ConfigMaps: cms,
  }
  prt := newPipelineRunTest(d, t)
  defer prt.Cancel()
@@ -5083,7 +5072,7 @@ func TestReconcileWithWhenExpressionsScopedToTask(t *testing.T) {
  }
 }
 
-func TestReconcileWithWhenExpressionsScopedToTaskWitResultRefs(t *testing.T) {
+func TestReconcileWithWhenExpressionsScopedToTaskWithResultRefs(t *testing.T) {
  names.TestingSeed()
  ps := []*v1beta1.Pipeline{{
  ObjectMeta: baseObjectMeta("test-pipeline", "foo"),
@@ -5160,22 +5149,12 @@ func TestReconcileWithWhenExpressionsScopedToTaskWitResultRefs(t *testing.T) {
  },
  },
  }}
- // set the scope of when expressions to task -- execution of dependent tasks is unblocked
- cms := []*corev1.ConfigMap{
- {
- ObjectMeta: metav1.ObjectMeta{Name: config.GetFeatureFlagsConfigName(), Namespace: system.Namespace()},
- Data: map[string]string{
- "scope-when-expressions-to-task": "true",
- },
- },
- }
 
  d := test.Data{
  PipelineRuns: prs,
  Pipelines: ps,
  Tasks: ts,
  TaskRuns: trs,
- ConfigMaps: cms,
  }
  prt := newPipelineRunTest(d, t)
  defer prt.Cancel()

pkg/reconciler/pipelinerun/resources/pipelinerunresolution.go

@@ -300,7 +300,7 @@ func (t *ResolvedPipelineRunTask) skipBecauseWhenExpressionsEvaluatedToFalse(fac
 }
 
 // skipBecauseParentTaskWasSkipped loops through the parent tasks and checks if the parent task skipped:
-// if yes, is it because of when expressions and are when expressions?
+// if yes, is it because of when expressions?
 // if yes, it ignores this parent skip and continue evaluating other parent tasks
 // if no, it returns true to skip the current task because this parent task was skipped
 // if no, it continues checking the other parent tasks
@@ -310,9 +310,9 @@ func (t *ResolvedPipelineRunTask) skipBecauseParentTaskWasSkipped(facts *Pipelin
  for _, p := range node.Prev {
  parentTask := stateMap[p.Task.HashKey()]
  if parentSkipStatus := parentTask.Skip(facts); parentSkipStatus.IsSkipped {
- // if the `when` expressions are scoped to task and the parent task was skipped due to its `when` expressions,
+ // if the parent task was skipped due to its `when` expressions,
  // then we should ignore that and continue evaluating if we should skip because of other parent tasks
- if parentSkipStatus.SkippingReason == WhenExpressionsSkip && facts.ScopeWhenExpressionsToTask {
+ if parentSkipStatus.SkippingReason == WhenExpressionsSkip {
  continue
  }
  return true