Propagate NodeSelector and Tolerations to Affinity Assistant

docs/install.md

@@ -245,7 +245,7 @@ The example below customizes the following:
 - the default timeout from 60 minutes to 20 minutes.
 - the default `app.kubernetes.io/managed-by` label is applied to all Pods created to execute `TaskRuns`.
 - the default Pod template to include a node selector to select the node where the Pod will be scheduled by default.
-  For more information, see [`PodTemplate` in `TaskRuns`](./taskruns.md#pod-template) or [`PodTemplate` in `PipelineRuns`](./pipelineruns.md#pod-template).
+  For more information, see [`PodTemplate` in `TaskRuns`](./taskruns.md#specifying-a-pod-template) or [`PodTemplate` in `PipelineRuns`](./pipelineruns.md#specifying-a-pod-template).
 
 ```yaml
 apiVersion: v1
@@ -270,7 +270,7 @@ To customize the behavior of the Pipelines Controller, modify the ConfigMap `fea
 
 - `disable-affinity-assistant` - set this flag to disable the [Affinity Assistant](./workspaces.md#affinity-assistant-and-specifying-workspace-order-in-a-pipeline)
   that is used to provide Node Affinity for `TaskRun` pods that share workspace volume. 
-  The Affinity Assistant pods may be incompatible with NodeSelector and other affinity rules
+  The Affinity Assistant is incompatible with other affinity rules
   configured for `TaskRun` pods.
 
   **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)

docs/workspaces.md

@@ -209,13 +209,15 @@ The `subPath` specified in a `Pipeline` will be appended to any `subPath` specif
 
 Sharing a `Workspace` between `Tasks` requires you to define the order in which those `Tasks`
 write to or read from that `Workspace`. Use the `runAfter` field in your `Pipeline` definition
-to define when a `Task` should be executed. For more information, see the [`runAfter` documentation](pipelines.md#runAfter).
+to define when a `Task` should be executed. For more information, see the [`runAfter` documentation](pipelines.md#using-the-runafter-parameter).
 
 When a `PersistentVolumeClaim` is used as volume source for a `Workspace` in a `PipelineRun`,
 an Affinity Assistant will be created. The Affinity Assistant acts as a placeholder for `TaskRun` pods
 sharing the same `Workspace`. All `TaskRun` pods within the `PipelineRun` that share the `Workspace`
 will be scheduled to the same Node as the Affinity Assistant pod. This means that Affinity Assistant is incompatible
-with e.g. NodeSelectors or other affinity rules configured for the `TaskRun` pods. The Affinity Assistant
+with e.g. other affinity rules configured for the `TaskRun` pods. If the `PipepineRun` 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. The Affinity Assistant can be disabled by setting the
 [disable-affinity-assistant](install.md#customizing-basic-execution-parameters) feature gate.
 

pkg/reconciler/pipelinerun/affinity_assistant.go

@@ -117,6 +117,18 @@ func affinityAssistantStatefulSet(name string, pr *v1beta1.PipelineRun, claimNam
 	// We want a singleton pod
 	replicas := int32(1)
 
+	// use tolerations from default podTemplate if specified
+	var tolerations []corev1.Toleration
+	if pr.Spec.PodTemplate != nil {
+		tolerations = pr.Spec.PodTemplate.Tolerations
+	}
+
+	// use nodeSelector from default podTemplate if specified
+	var nodeSelector map[string]string
+	if pr.Spec.PodTemplate != nil {
+		nodeSelector = pr.Spec.PodTemplate.NodeSelector
+	}
+
 	containers := []corev1.Container{{
 		Name: "affinity-assistant",
 
@@ -171,7 +183,9 @@ func affinityAssistantStatefulSet(name string, pr *v1beta1.PipelineRun, claimNam
 					Labels: getStatefulSetLabels(pr, name),
 				},
 				Spec: corev1.PodSpec{
-					Containers: containers,
+					Containers:   containers,
+					Tolerations:  tolerations,
+					NodeSelector: nodeSelector,
 					Affinity: &corev1.Affinity{
 						PodAntiAffinity: &corev1.PodAntiAffinity{
 							PreferredDuringSchedulingIgnoredDuringExecution: []corev1.WeightedPodAffinityTerm{repelOtherAffinityAssistantsPodAffinityTerm},

pkg/reconciler/pipelinerun/affinity_assistant_test.go

@@ -82,6 +82,58 @@ func TestCreateAndDeleteOfAffinityAssistant(t *testing.T) {
 	}
 }
 
+func TestThatCustomTolerationsAndNodeSelectorArePropagatedToAffinityAssistant(t *testing.T) {
+	prWithCustomPodTemplate := &v1beta1.PipelineRun{
+		TypeMeta: metav1.TypeMeta{Kind: "PipelineRun"},
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "pipelinerun-with-custom-podtemplate",
+		},
+		Spec: v1beta1.PipelineRunSpec{
+			PodTemplate: &v1beta1.PodTemplate{
+				Tolerations: []corev1.Toleration{{
+					Key:      "key",
+					Operator: "Equal",
+					Value:    "value",
+					Effect:   "NoSchedule",
+				}},
+				NodeSelector: map[string]string{
+					"disktype": "ssd",
+				},
+			},
+		},
+	}
+
+	stsWithTolerationsAndNodeSelector := affinityAssistantStatefulSet("test-assistant", prWithCustomPodTemplate, "mypvc")
+
+	if len(stsWithTolerationsAndNodeSelector.Spec.Template.Spec.Tolerations) != 1 {
+		t.Errorf("expected Tolerations in the StatefulSet")
+	}
+
+	if len(stsWithTolerationsAndNodeSelector.Spec.Template.Spec.NodeSelector) != 1 {
+		t.Errorf("expected a NodeSelector in the StatefulSet")
+	}
+}
+
+func TestThatTheAffinityAssistantIsWithoutNodeSelectorAndTolerations(t *testing.T) {
+	prWithoutCustomPodTemplate := &v1beta1.PipelineRun{
+		TypeMeta: metav1.TypeMeta{Kind: "PipelineRun"},
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "pipelinerun-without-custom-podtemplate",
+		},
+		Spec: v1beta1.PipelineRunSpec{},
+	}
+
+	stsWithoutTolerationsAndNodeSelector := affinityAssistantStatefulSet("test-assistant", prWithoutCustomPodTemplate, "mypvc")
+
+	if len(stsWithoutTolerationsAndNodeSelector.Spec.Template.Spec.Tolerations) != 0 {
+		t.Errorf("unexpected Tolerations in the StatefulSet")
+	}
+
+	if len(stsWithoutTolerationsAndNodeSelector.Spec.Template.Spec.NodeSelector) != 0 {
+		t.Errorf("unexpected NodeSelector in the StatefulSet")
+	}
+}
+
 func TestDisableAffinityAssistant(t *testing.T) {
 	for _, tc := range []struct {
 		description string