feat: Support arbitrarily setting `privileged: true` for runner container (#1383)

Resolves #1282

README.md

@@ -444,6 +444,17 @@ spec:
           requests:
             cpu: "2.0"
             memory: "4Gi"
+        # This is an advanced configuration. Don't touch it unless you know what you're doing.
+        securityContext:
+          # Usually, the runner container's privileged field is derived from dockerdWithinRunnerContainer.
+          # But in the case where you need to run privileged job steps even if you don't use docker/don't need dockerd within the runner container,
+          # just specified `privileged: true` like this.
+          # See https://github.com/actions-runner-controller/actions-runner-controller/issues/1282
+          # Do note that specifying `privileged: false` while using dind is very likely to fail, even if you use some vm-based container runtimes
+          # like firecracker and kata. Basically they run containers within dedicated micro vms and so
+          # it's more like you can use `privileged: true` safer with those runtimes.
+          #
+          # privileged: true
       - name: docker
         resources:
           limits:
@@ -1138,6 +1149,18 @@ spec:
       # 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"
+      # This is an advanced configuration. Don't touch it unless you know what you're doing.
+      containers:
+      - name: runner
+        # Usually, the runner container's privileged field is derived from dockerdWithinRunnerContainer.
+        # But in the case where you need to run privileged job steps even if you don't use docker/don't need dockerd within the runner container,
+        # just specified `privileged: true` like this.
+        # See https://github.com/actions-runner-controller/actions-runner-controller/issues/1282
+        # Do note that specifying `privileged: false` while using dind is very likely to fail, even if you use some vm-based container runtimes
+        # like firecracker and kata. Basically they run containers within dedicated micro vms and so
+        # it's more like you can use `privileged: true` safer with those runtimes.
+        #
+        # privileged: true
 ```
 
 ### Custom Volume mounts

controllers/new_runner_pod_test.go

@@ -388,8 +388,7 @@ func TestNewRunnerPod(t *testing.T) {
 				DockerEnabled: boolPtr(false),
 			},
 			want: newTestPod(dockerDisabled, func(p *corev1.Pod) {
-				// TODO
-				// p.Spec.Containers[0].SecurityContext.Privileged = boolPtr(true)
+				p.Spec.Containers[0].SecurityContext.Privileged = boolPtr(true)
 			}),
 		},
 	}
@@ -880,7 +879,7 @@ func TestNewRunnerPodFromRunnerController(t *testing.T) {
 			},
 
 			want: newTestPod(dockerDisabled, func(p *corev1.Pod) {
-				// p.Spec.Containers[0].SecurityContext.Privileged = boolPtr(true)
+				p.Spec.Containers[0].SecurityContext.Privileged = boolPtr(true)
 			}),
 		},
 	}

controllers/runner_controller.go

@@ -349,24 +349,51 @@ func (r *RunnerReconciler) newPod(runner v1alpha1.Runner) (corev1.Pod, error) {
 	if len(runner.Spec.Containers) == 0 {
 		template.Spec.Containers = append(template.Spec.Containers, corev1.Container{
 			Name: "runner",
-			ImagePullPolicy: runner.Spec.ImagePullPolicy,
-			EnvFrom:         runner.Spec.EnvFrom,
-			Env:             runner.Spec.Env,
-			Resources:       runner.Spec.Resources,
 		})
 
 		if (runner.Spec.DockerEnabled == nil || *runner.Spec.DockerEnabled) && (runner.Spec.DockerdWithinRunnerContainer == nil || !*runner.Spec.DockerdWithinRunnerContainer) {
 			template.Spec.Containers = append(template.Spec.Containers, corev1.Container{
 				Name: "docker",
-				VolumeMounts: runner.Spec.DockerVolumeMounts,
-				Resources:    runner.Spec.DockerdContainerResources,
-				Env:          runner.Spec.DockerEnv,
 			})
 		}
 	} else {
 		template.Spec.Containers = runner.Spec.Containers
 	}
 
+	for i, c := range template.Spec.Containers {
+		switch c.Name {
+		case "runner":
+			if c.ImagePullPolicy == "" {
+				template.Spec.Containers[i].ImagePullPolicy = runner.Spec.ImagePullPolicy
+			}
+			if len(c.EnvFrom) == 0 {
+				template.Spec.Containers[i].EnvFrom = runner.Spec.EnvFrom
+			}
+			if len(c.Env) == 0 {
+				template.Spec.Containers[i].Env = runner.Spec.Env
+			}
+			if len(c.Resources.Requests) == 0 {
+				template.Spec.Containers[i].Resources.Requests = runner.Spec.Resources.Requests
+			}
+			if len(c.Resources.Limits) == 0 {
+				template.Spec.Containers[i].Resources.Limits = runner.Spec.Resources.Limits
+			}
+		case "docker":
+			if len(c.VolumeMounts) == 0 {
+				template.Spec.Containers[i].VolumeMounts = runner.Spec.DockerVolumeMounts
+			}
+			if len(c.Resources.Limits) == 0 {
+				template.Spec.Containers[i].Resources.Limits = runner.Spec.DockerdContainerResources.Limits
+			}
+			if len(c.Resources.Requests) == 0 {
+				template.Spec.Containers[i].Resources.Requests = runner.Spec.DockerdContainerResources.Requests
+			}
+			if len(c.Env) == 0 {
+				template.Spec.Containers[i].Env = runner.Spec.DockerEnv
+			}
+		}
+	}
+
 	template.Spec.SecurityContext = runner.Spec.SecurityContext
 	template.Spec.EnableServiceLinks = runner.Spec.EnableServiceLinks
 
@@ -623,8 +650,11 @@ func newRunnerPod(runnerName string, template corev1.Pod, runnerSpec v1alpha1.Ru
 	if runnerContainer.SecurityContext == nil {
 		runnerContainer.SecurityContext = &corev1.SecurityContext{}
 	}
+
+	if runnerContainer.SecurityContext.Privileged == nil {
 		// Runner need to run privileged if it contains DinD
 		runnerContainer.SecurityContext.Privileged = &dockerdInRunnerPrivileged
+	}
 
 	pod := template.DeepCopy()