feat: allow specifying runtime class in runner spec (actions#580)

This allows using the `runtimeClassName` directive in the runner's spec.

One of the use-cases for this is Kata Containers, which use `runtimeClassName` in a pod spec as an indicator that the pod should run inside a Kata container. This allows us a greater degree of pod isolation.

README.md

@@ -771,7 +771,7 @@ spec:
       # - https://cloud.google.com/container-registry/docs/pulling-cached-images
       dockerRegistryMirror: https://mirror.gcr.io/
       # false (default) = Docker support is provided by a sidecar container deployed in the runner pod.
-      # true = No docker sidecar container is deployed in the runner pod but docker can be used within teh runner container instead. The image summerwind/actions-runner-dind is used by default.
+      # true = No docker sidecar container is deployed in the runner pod but docker can be used within the runner container instead. The image summerwind/actions-runner-dind is used by default.
       dockerdWithinRunnerContainer: true
       # Docker sidecar container image tweaks examples below, only applicable if dockerdWithinRunnerContainer = false
       dockerdContainerResources:
@@ -805,6 +805,10 @@ spec:
       dockerVolumeMounts:
         - mountPath: /var/lib/docker
           name: docker-extra
+      # Optional name of the container runtime configuration that should be used for pods.
+      # This must match the name of a RuntimeClass resource available on the cluster.
+      # More info: https://kubernetes.io/docs/concepts/containers/runtime-class
+      runtimeClassName: "runc"
 ```
 
 ### Runner Labels

api/v1alpha1/runner_types.go

@@ -107,6 +107,11 @@ type RunnerSpec struct {
 	HostAliases []corev1.HostAlias `json:"hostAliases,omitempty"`
 	// +optional
 	VolumeSizeLimit *resource.Quantity `json:"volumeSizeLimit,omitempty"`
+
+	// RuntimeClassName is the container runtime configuration that containers should run under.
+	// More info: https://kubernetes.io/docs/concepts/containers/runtime-class
+	// +optional
+	RuntimeClassName *string `json:"runtimeClassName,omitempty"`
 }
 
 // ValidateRepository validates repository field.

charts/actions-runner-controller/crds/actions.summerwind.dev_runnerdeployments.yaml

@@ -688,6 +688,9 @@ spec:
                           description: 'Requests describes the minimum amount of compute resources required. If Requests is omitted for a container, it defaults to Limits if that is explicitly specified, otherwise to an implementation-defined value. More info: https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/'
                           type: object
                       type: object
+                    runtimeClassName:
+                      description: 'RuntimeClassName is the container runtime configuration that containers should run under. More info: https://kubernetes.io/docs/concepts/containers/runtime-class'
+                      type: string
                     securityContext:
                       description: PodSecurityContext holds pod-level security attributes and common container settings. Some fields are also present in container.securityContext.  Field values of container.securityContext take precedence over field values of PodSecurityContext.
                       properties:

charts/actions-runner-controller/crds/actions.summerwind.dev_runnerreplicasets.yaml

@@ -685,6 +685,9 @@ spec:
                           description: 'Requests describes the minimum amount of compute resources required. If Requests is omitted for a container, it defaults to Limits if that is explicitly specified, otherwise to an implementation-defined value. More info: https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/'
                           type: object
                       type: object
+                    runtimeClassName:
+                      description: 'RuntimeClassName is the container runtime configuration that containers should run under. More info: https://kubernetes.io/docs/concepts/containers/runtime-class'
+                      type: string
                     securityContext:
                       description: PodSecurityContext holds pod-level security attributes and common container settings. Some fields are also present in container.securityContext.  Field values of container.securityContext take precedence over field values of PodSecurityContext.
                       properties:

charts/actions-runner-controller/crds/actions.summerwind.dev_runners.yaml

@@ -650,6 +650,9 @@ spec:
                   description: 'Requests describes the minimum amount of compute resources required. If Requests is omitted for a container, it defaults to Limits if that is explicitly specified, otherwise to an implementation-defined value. More info: https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/'
                   type: object
               type: object
+            runtimeClassName:
+              description: 'RuntimeClassName is the container runtime configuration that containers should run under. More info: https://kubernetes.io/docs/concepts/containers/runtime-class'
+              type: string
             securityContext:
               description: PodSecurityContext holds pod-level security attributes and common container settings. Some fields are also present in container.securityContext.  Field values of container.securityContext take precedence over field values of PodSecurityContext.
               properties:

config/crd/bases/actions.summerwind.dev_runnerdeployments.yaml

@@ -688,6 +688,9 @@ spec:
                           description: 'Requests describes the minimum amount of compute resources required. If Requests is omitted for a container, it defaults to Limits if that is explicitly specified, otherwise to an implementation-defined value. More info: https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/'
                           type: object
                       type: object
+                    runtimeClassName:
+                      description: 'RuntimeClassName is the container runtime configuration that containers should run under. More info: https://kubernetes.io/docs/concepts/containers/runtime-class'
+                      type: string
                     securityContext:
                       description: PodSecurityContext holds pod-level security attributes and common container settings. Some fields are also present in container.securityContext.  Field values of container.securityContext take precedence over field values of PodSecurityContext.
                       properties:

config/crd/bases/actions.summerwind.dev_runnerreplicasets.yaml

@@ -685,6 +685,9 @@ spec:
                           description: 'Requests describes the minimum amount of compute resources required. If Requests is omitted for a container, it defaults to Limits if that is explicitly specified, otherwise to an implementation-defined value. More info: https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/'
                           type: object
                       type: object
+                    runtimeClassName:
+                      description: 'RuntimeClassName is the container runtime configuration that containers should run under. More info: https://kubernetes.io/docs/concepts/containers/runtime-class'
+                      type: string
                     securityContext:
                       description: PodSecurityContext holds pod-level security attributes and common container settings. Some fields are also present in container.securityContext.  Field values of container.securityContext take precedence over field values of PodSecurityContext.
                       properties:

config/crd/bases/actions.summerwind.dev_runners.yaml

@@ -650,6 +650,9 @@ spec:
                   description: 'Requests describes the minimum amount of compute resources required. If Requests is omitted for a container, it defaults to Limits if that is explicitly specified, otherwise to an implementation-defined value. More info: https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/'
                   type: object
               type: object
+            runtimeClassName:
+              description: 'RuntimeClassName is the container runtime configuration that containers should run under. More info: https://kubernetes.io/docs/concepts/containers/runtime-class'
+              type: string
             securityContext:
               description: PodSecurityContext holds pod-level security attributes and common container settings. Some fields are also present in container.securityContext.  Field values of container.securityContext take precedence over field values of PodSecurityContext.
               properties:

controllers/runner_controller.go

@@ -910,6 +910,10 @@ func (r *RunnerReconciler) newPod(runner v1alpha1.Runner) (corev1.Pod, error) {
 		pod.Spec.HostAliases = runner.Spec.HostAliases
 	}
 
+	if runner.Spec.RuntimeClassName != nil {
+		pod.Spec.RuntimeClassName = runner.Spec.RuntimeClassName
+	}
+
 	if err := ctrl.SetControllerReference(&runner, &pod, r.Scheme); err != nil {
 		return pod, err
 	}