cleanup: [TEP-0135] remove deprecated disable-affinity-assistant feature flag

This field has been deprecated for about a year and half. So this is
"removing" this feature flag from the codebase.

The field is kept in the go code to provide a backward compatibility
for client code (like chains, …) but it will be disallowed by the
webhook. It will also be completely ignore by the rest of the code.

Author: l-qing

Diff for: config/300-crds/300-pipelinerun.yaml

@@ -2565,9 +2565,8 @@ spec:
                           type: boolean
                         coschedule:
                           type: string
-                        disableAffinityAssistant:
-                          type: boolean
                         disableCredsInit:
+                          description: DisableAffinityAssistant         bool `json:"disableAffinityAssistant,omitempty"`
                           type: boolean
                         disableInlineSpec:
                           type: string
@@ -2979,9 +2978,8 @@ spec:
                                     type: boolean
                                   coschedule:
                                     type: string
-                                  disableAffinityAssistant:
-                                    type: boolean
                                   disableCredsInit:
+                                    description: DisableAffinityAssistant         bool `json:"disableAffinityAssistant,omitempty"`
                                     type: boolean
                                   disableInlineSpec:
                                     type: string
@@ -3267,9 +3265,8 @@ spec:
                                           type: boolean
                                         coschedule:
                                           type: string
-                                        disableAffinityAssistant:
-                                          type: boolean
                                         disableCredsInit:
+                                          description: DisableAffinityAssistant         bool `json:"disableAffinityAssistant,omitempty"`
                                           type: boolean
                                         disableInlineSpec:
                                           type: string
@@ -5876,9 +5873,8 @@ spec:
                           type: boolean
                         coschedule:
                           type: string
-                        disableAffinityAssistant:
-                          type: boolean
                         disableCredsInit:
+                          description: DisableAffinityAssistant         bool `json:"disableAffinityAssistant,omitempty"`
                           type: boolean
                         disableInlineSpec:
                           type: string

Diff for: config/300-crds/300-taskrun.yaml

@@ -1948,9 +1948,8 @@ spec:
                           type: boolean
                         coschedule:
                           type: string
-                        disableAffinityAssistant:
-                          type: boolean
                         disableCredsInit:
+                          description: DisableAffinityAssistant         bool `json:"disableAffinityAssistant,omitempty"`
                           type: boolean
                         disableInlineSpec:
                           type: string
@@ -2236,9 +2235,8 @@ spec:
                                 type: boolean
                               coschedule:
                                 type: string
-                              disableAffinityAssistant:
-                                type: boolean
                               disableCredsInit:
+                                description: DisableAffinityAssistant         bool `json:"disableAffinityAssistant,omitempty"`
                                 type: boolean
                               disableInlineSpec:
                                 type: string
@@ -4135,9 +4133,8 @@ spec:
                           type: boolean
                         coschedule:
                           type: string
-                        disableAffinityAssistant:
-                          type: boolean
                         disableCredsInit:
+                          description: DisableAffinityAssistant         bool `json:"disableAffinityAssistant,omitempty"`
                           type: boolean
                         disableInlineSpec:
                           type: string
@@ -4389,9 +4386,8 @@ spec:
                                 type: boolean
                               coschedule:
                                 type: string
-                              disableAffinityAssistant:
-                                type: boolean
                               disableCredsInit:
+                                description: DisableAffinityAssistant         bool `json:"disableAffinityAssistant,omitempty"`
                                 type: boolean
                               disableInlineSpec:
                                 type: string

Diff for: config/config-feature-flags.yaml

@@ -21,17 +21,6 @@ metadata:
     app.kubernetes.io/instance: default
     app.kubernetes.io/part-of: tekton-pipelines
 data:
-  # Setting this flag to "true" will prevent Tekton to create an
-  # Affinity Assistant for every TaskRun sharing a PVC workspace
-  #
-  # The default behaviour is for Tekton to create Affinity Assistants
-  #
-  # See more in the Affinity Assistant documentation
-  # https://github.com/tektoncd/pipeline/blob/main/docs/affinityassistants.md
-  # or https://github.com/tektoncd/pipeline/pull/2630 for more info.
-  #
-  # Note: This feature flag is deprecated and will be removed in release v0.60. Consider using `coschedule` feature flag to configure Affinity Assistant behavior.
-  disable-affinity-assistant: "false"
   # Setting this flag will determine how PipelineRun Pods are scheduled with Affinity Assistant.
   # Acceptable values are "workspaces" (default), "pipelineruns", "isolate-pipelinerun", or "disabled".
   #

Diff for: docs/additional-configs.md

@@ -275,21 +275,6 @@ that are running while the change occurs.
 
 The flags in this ConfigMap are as follows:
 
-- `disable-affinity-assistant` - set this flag to `true` to disable the [Affinity Assistant](./affinityassistants)
-  that is used to provide Node Affinity for `TaskRun` pods that share workspace volume.
-  The Affinity Assistant is incompatible with other affinity rules
-  configured for `TaskRun` pods.
-
-  **Note:** This feature flag is deprecated and will be removed in release `v0.60`. Consider using `coschedule` feature flag to configure Affinity Assistant behavior.
-
-  **Note:** Affinity Assistant use [Inter-pod affinity and anti-affinity](https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#inter-pod-affinity-and-anti-affinity)
-  that require substantial amount of processing which can slow down scheduling in large clusters
-  significantly. We do not recommend using them in clusters larger than several hundred nodes
-
-  **Note:** Pod anti-affinity requires nodes to be consistently labelled, in other words every
-  node in the cluster must have an appropriate label matching `topologyKey`. If some or all nodes
-  are missing the specified `topologyKey` label, it can lead to unintended behavior.
-
 - `coschedule`: set this flag determines how PipelineRun Pods are scheduled with [Affinity Assistant](./affinityassistants).
 Acceptable values are "workspaces" (default), "pipelineruns", "isolate-pipelinerun", or "disabled".
 Setting it to "workspaces" will schedule all the taskruns sharing the same PVC-based workspace in a pipelinerun to the same node.

Diff for: docs/affinityassistants.md

@@ -6,10 +6,11 @@ weight: 405
 -->
 
 # Affinity Assistants
+
 Affinity Assistant is a feature to coschedule `PipelineRun` `pods` to the same node
 based on [kubernetes pod affinity](https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#inter-pod-affinity-and-anti-affinity) so that it possible for the taskruns to execute parallel while sharing volume.
 Available Affinity Assistant Modes are **coschedule workspaces**, **coschedule pipelineruns**,
-**isolate pipelinerun** and **disabled**. 
+**isolate pipelinerun** and **disabled**.
 
 > :seedling: **coschedule pipelineruns** and **isolate pipelinerun** modes are [**alpha features**](./additional-configs.md#alpha-features).
 > **coschedule workspaces** is a **stable feature**
@@ -27,10 +28,10 @@ and only one PipelineRun is allowed to run on a node at a time.
 This means that Affinity Assistant is incompatible with other affinity rules
 configured for the `TaskRun` pods (i.e. other affinity rules specified in custom [PodTemplate](pipelineruns.md#specifying-a-pod-template) will be overwritten by Affinity Assistant).
 If the `PipelineRun` has a custom [PodTemplate](pipelineruns.md#specifying-a-pod-template) configured, the `NodeSelector` and `Tolerations` fields will also be set on the Affinity Assistant pod. The Affinity Assistant
-is deleted when the `PipelineRun` is completed. 
+is deleted when the `PipelineRun` is completed.
 
-Currently, the Affinity Assistant Modes can be configured by the `disable-affinity-assistant` and `coschedule` feature flags. 
-The `disable-affinity-assistant` feature flag is now deprecated and will be removed in release `v0.60`. At the time, the Affinity Assistant Modes will be only determined by the `coschedule` feature flag. 
+The Affinity Assistant Modes are configured by the `coschedule` feature flag.
+Previously, it was also controlled by the `disable-affinity-assistant` feature flag which was deprecated and removed after release `v0.68`.
 
 The following chart summarizes the Affinity Assistant Modes with different combinations of the `disable-affinity-assistant` and `coschedule` feature flags during migration (when both feature flags are present) and after the migration (when only the `coschedule` flag is present).
 
@@ -95,7 +96,7 @@ The following chart summarizes the Affinity Assistant Modes with different combi
     </tbody>
 </table>
 
-**Note:** For users who previously accepted the default behavior (`disable-affinity-assistant`: `false`) but now want one of the new features, you need to set `disable-affinity-assistant` to "true" and then turn on the new behavior by setting the `coschedule` flag. For users who previously disabled the affinity assistant but want one of the new features, just set the `coschedule` flag accordingly.
+**Note:** After release `v0.68`, the `disable-affinity-assistant` feature flag is removed and the Affinity Assistant Modes are only controlled by the `coschedule` feature flag.
 
 **Note:** Affinity Assistant use [Inter-pod affinity and anti-affinity](https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#inter-pod-affinity-and-anti-affinity)
 that require substantial amount of processing which can slow down scheduling in large clusters

Diff for: docs/artifacts.md

@@ -501,7 +501,6 @@ Upon resolution and execution of the `TaskRun`, the `Status` will look something
       "featureFlags": {
         "awaitSidecarReadiness": true,
         "coschedule": "workspaces",
-        "disableAffinityAssistant": false,
         "disableCredsInit": false,
         "disableInlineSpec": "",
         "enableAPIFields": "beta",

Diff for: docs/deprecations.md

@@ -26,7 +26,6 @@ The following features are deprecated but have not yet been removed.
 | [The `config-trusted-resources` configMap is deprecated](https://github.com/tektoncd/pipeline/issues/5852)                                                                                                                 | v0.45.0                                                              | Alpha                                                                                                  | v0.46.0                       |
 | [The `default-cloud-events-sink` setting in the `config-defaults` configMap is deprecated](https://github.com/tektoncd/pipeline/pull/6883) in favour of the new `config-events` configMap.                                                                                                                | v0.50.0                                                              | N/A                                                                                                  | v0.59.0                       |
 | [v1beta1 Tasks, TaskRuns, Pipelines, and PipelineRuns are deprecated in favor of v1](https://github.com/tektoncd/pipeline/issues/5541)                                                                                                                 | v0.50.0                                                              | Beta                                                                                                  | v0.62.0                       |
-| [The `disable-affinity-assistant` feature flag is deprecated in favor of the `coschedule` feature flag](https://github.com/tektoncd/pipeline/issues/6988)                                                                                                                 | v0.51.0                                                              | N/A                                                                                                  | April 27, 2024                       |
 | The `resolver framework` is [deprecated](https://github.com/tektoncd/pipeline/pull/7945) in favor of an [upgraded framework](https://github.com/tektoncd/pipeline/pull/7910)                                                                                                                   | v0.60.0                                                              | N/A                                                                                                  | v0.72.                      |
 
 ### v1beta1 deprecation
@@ -46,6 +45,8 @@ The features listed below have been removed but may still be supported in releas
 | [The `PipelineRun.Status.TaskRuns` and `PipelineRun.Status.Runs` fields and the `embedded-status` feature flag along with their functionalities have been tombstoned since v0.45.](https://github.com/tektoncd/community/blob/main/teps/0100-embedded-taskruns-and-runs-status-in-pipelineruns.md)                                                             | [[TEP100] Remove Taskruns and Runs Fields for PipelineRunStatus](https://github.com/tektoncd/pipeline/pull/6099)         | Jan 25, 2023 | v0.44.0 | Jan 24, 2024 |
 | PipelineResources are removed, along with the components of the API that rely on them as proposed in [TEP-0074](https://github.com/tektoncd/community/blob/main/teps/0074-deprecate-pipelineresources.md). See [Removed `PipelineResources` related features](#removed-pipelineresources-related-features) for more info. | [[TEP074] Remove Generic PipelineResources with Rest of Resources Types](https://github.com/tektoncd/pipeline/pull/6150) | Mar 8, 2023  | v0.44.0 | Jan 24, 2024 |
 | v1alpha1 Runs are removed, as proposed in [TEP-0114](https://github.com/tektoncd/community/blob/main/teps/0114-custom-tasks-beta.md), along with the feature flags `enable-custom-task` and `custom-task-version`. | [TEP-0114: Remove support for v1alpha1.Run](https://github.com/tektoncd/pipeline/pull/6508) | April 7, 2023  | v0.44.0 | Jan 24, 2024 |
+| [The `disable-affinity-assistant` feature flag is deprecated in favor of the `coschedule` feature flag](https://github.com/tektoncd/community/blob/main/teps/0135-coscheduling-pipelinerun-pods.md#tep-0135-coscheduling-pipelinerun-pods)                                                                                                                 | [cleanup: [TEP-0135] remove deprecated disable-affinity-assistant feature flag](https://github.com/tektoncd/pipeline/pull/8603) | Mar 1, 2025                                                                         | v0.68.0                         | Jan 30, 2026                       |
+
 
 ### Removed PipelineResources related features:
 

Diff for: pkg/apis/config/feature_flags.go

@@ -60,8 +60,6 @@ const (
 	ResultExtractionMethodTerminationMessage = "termination-message"
 	// ResultExtractionMethodSidecarLogs is the value used for "results-from" as a way to extract results from tasks using sidecar logs.
 	ResultExtractionMethodSidecarLogs = "sidecar-logs"
-	// DefaultDisableAffinityAssistant is the default value for "disable-affinity-assistant".
-	DefaultDisableAffinityAssistant = false
 	// DefaultDisableCredsInit is the default value for "disable-creds-init".
 	DefaultDisableCredsInit = false
 	// DefaultRunningInEnvWithInjectedSidecars is the default value for "running-in-environment-with-injected-sidecars".
@@ -119,7 +117,6 @@ const (
 	// in Taskrun or Pipelinerun
 	DisableInlineSpec = "disable-inline-spec"
 
-	disableAffinityAssistantKey         = "disable-affinity-assistant"
 	disableCredsInitKey                 = "disable-creds-init"
 	runningInEnvWithInjectedSidecarsKey = "running-in-environment-with-injected-sidecars"
 	awaitSidecarReadinessKey            = "await-sidecar-readiness"
@@ -188,7 +185,7 @@ var (
 // FeatureFlags holds the features configurations
 // +k8s:deepcopy-gen=true
 type FeatureFlags struct {
-	DisableAffinityAssistant         bool `json:"disableAffinityAssistant,omitempty"`
+	// DisableAffinityAssistant         bool `json:"disableAffinityAssistant,omitempty"`
 	DisableCredsInit                 bool `json:"disableCredsInit,omitempty"`
 	RunningInEnvWithInjectedSidecars bool `json:"runningInEnvWithInjectedSidecars,omitempty"`
 	RequireGitSSHSecretKnownHosts    bool `json:"requireGitSSHSecretKnownHosts,omitempty"`
@@ -259,9 +256,6 @@ func NewFeatureFlagsFromMap(cfgMap map[string]string) (*FeatureFlags, error) {
 	}
 
 	tc := FeatureFlags{}
-	if err := setFeature(disableAffinityAssistantKey, DefaultDisableAffinityAssistant, &tc.DisableAffinityAssistant); err != nil {
-		return nil, err
-	}
 	if err := setFeature(disableCredsInitKey, DefaultDisableCredsInit, &tc.DisableCredsInit); err != nil {
 		return nil, err
 	}
@@ -304,7 +298,7 @@ func NewFeatureFlagsFromMap(cfgMap map[string]string) (*FeatureFlags, error) {
 	if err := setFeature(setSecurityContextReadOnlyRootFilesystemKey, DefaultSetSecurityContextReadOnlyRootFilesystem, &tc.SetSecurityContextReadOnlyRootFilesystem); err != nil {
 		return nil, err
 	}
-	if err := setCoschedule(cfgMap, DefaultCoschedule, tc.DisableAffinityAssistant, &tc.Coschedule); err != nil {
+	if err := setCoschedule(cfgMap, DefaultCoschedule, &tc.Coschedule); err != nil {
 		return nil, err
 	}
 	if err := setPerFeatureFlag(EnableCELInWhenExpression, DefaultEnableCELInWhenExpression, &tc.EnableCELInWhenExpression); err != nil {
@@ -350,20 +344,14 @@ func setEnabledAPIFields(cfgMap map[string]string, defaultValue string, feature
 }
 
 // setCoschedule sets the "coschedule" flag based on the content of a given map.
-// If the feature gate is invalid or incompatible with `disable-affinity-assistant`, then an error is returned.
-func setCoschedule(cfgMap map[string]string, defaultValue string, disabledAffinityAssistant bool, feature *string) error {
+func setCoschedule(cfgMap map[string]string, defaultValue string, feature *string) error {
 	value := defaultValue
 	if cfg, ok := cfgMap[coscheduleKey]; ok {
 		value = strings.ToLower(cfg)
 	}
 
 	switch value {
 	case CoscheduleDisabled, CoscheduleWorkspaces, CoschedulePipelineRuns, CoscheduleIsolatePipelineRun:
-		// validate that "coschedule" is compatible with "disable-affinity-assistant"
-		// "coschedule" must be set to "workspaces" when "disable-affinity-assistant" is false
-		if !disabledAffinityAssistant && value != CoscheduleWorkspaces {
-			return fmt.Errorf("coschedule value %v is incompatible with %v setting to false", value, disableAffinityAssistantKey)
-		}
 		*feature = value
 	default:
 		return fmt.Errorf("invalid value for feature flag %q: %q", coscheduleKey, value)