[TektonConfig] Allows user to set priorityClassName parameter

docs/TektonConfig.md

@@ -35,6 +35,7 @@ The TektonConfig CR provides the following features
     config:
       nodeSelector: <>
       tolerations: []
+      priorityClassName: system-cluster-critical
     pipeline:
       disable-affinity-assistant: false
       disable-creds-init: false
@@ -86,6 +87,7 @@ Config provides fields to configure deployments created by the Operator.
 This provides following fields:
 - [`nodeSelector`][node-selector]
 - [`tolerations`][tolerations]
+- [`priorityClassName`][priorityClassName]
 
 User can pass the required fields and this would be passed to all Operator components which will get added in all
 deployments created by Operator.
@@ -100,11 +102,13 @@ config:
     operator: "Equal"
     value: "value1"
     effect: "NoSchedule"
+  priorityClassName: system-node-critical
 ```
 
 This is an `Optional` section.
 
-
+**NOTE**: If `spec.config.priorityClassName` is used, then the required [`priorityClass`][priorityClass] is 
+expected to be created by the user to get the Tekton resources pods in running state
 ### Pipeline
 Pipeline section allows user to customize the Tekton pipeline features. This allow user to customize the values in configmaps.
 
@@ -203,3 +207,6 @@ This is an `Optional` section.
 [node-selector]:https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#nodeselector
 [tolerations]:https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration/
 [schedule]:https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/#cron-schedule-syntax
+[priorityClassName]: https://kubernetes.io/docs/concepts/scheduling-eviction/pod-priority-preemption/#pod-priority
+[priorityClass]: https://kubernetes.io/docs/concepts/scheduling-eviction/pod-priority-preemption/#priorityclass
+

pkg/apis/operator/v1alpha1/tektonconfig_types.go

@@ -125,4 +125,7 @@ type TektonConfigList struct {
 type Config struct {
 	NodeSelector map[string]string   `json:"nodeSelector,omitempty"`
 	Tolerations  []corev1.Toleration `json:"tolerations,omitempty"`
+	// PriorityClassName holds the priority class to be set to pod template
+	// +optional
+	PriorityClassName string `json:"priorityClassName,omitempty"`
 }

pkg/reconciler/common/transformers.go

@@ -580,6 +580,7 @@ func AddConfiguration(config v1alpha1.Config) mf.Transformer {
 
 		d.Spec.Template.Spec.NodeSelector = config.NodeSelector
 		d.Spec.Template.Spec.Tolerations = config.Tolerations
+		d.Spec.Template.Spec.PriorityClassName = config.PriorityClassName
 
 		unstrObj, err := runtime.DefaultUnstructuredConverter.ToUnstructured(d)
 		if err != nil {

pkg/reconciler/common/transformers_test.go

@@ -501,6 +501,7 @@ func TestAddConfiguration(t *testing.T) {
 				Effect:   "noSchedule",
 			},
 		},
+		PriorityClassName: string("system-cluster-critical"),
 	}
 
 	manifest, err = manifest.Transform(AddConfiguration(config))
@@ -509,7 +510,7 @@ func TestAddConfiguration(t *testing.T) {
 	d := &v1beta1.Deployment{}
 	err = runtime.DefaultUnstructuredConverter.FromUnstructured(manifest.Resources()[0].Object, d)
 	assertNoEror(t, err)
-
 	assert.Equal(t, d.Spec.Template.Spec.NodeSelector["foo"], config.NodeSelector["foo"])
 	assert.Equal(t, d.Spec.Template.Spec.Tolerations[0].Key, config.Tolerations[0].Key)
+	assert.Equal(t, d.Spec.Template.Spec.PriorityClassName, config.PriorityClassName)
 }