Documentation enhancements (#207)

This PR addresses the issue listed in issue #170 regarding how to set up rootless Docker. It also expands on the documentation to show how to create deployments for different environments.

Co-authored-by: ccureau <ccureau@noreply.gitea.io>
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/207
Reviewed-by: Jason Song <i@wolfogre.com>
Co-authored-by: Chris Cureau <cmcureau@gmail.com>
Co-committed-by: Chris Cureau <cmcureau@gmail.com>

examples/kubernetes/README.md

@@ -0,0 +1,8 @@
+## Kubernetes Docker in Docker Deployment with `act_runner`
+
+NOTE: Docker in Docker (dind) requires elevated privileges on Kubernetes. The current way to achieve this is to set the pod `SecurityContext` to `privileged`. Keep in mind that this is a potential security issue that has the potential for a malicious application to break out of the container context.
+
+Files in this directory:
+
+- [`dind-docker.yaml`](dind-docker.yaml)
+  How to create a Deployment and Persistent Volume for Kubernetes to act as a runner. The Docker credentials are re-generated each time the pod connects and does not need to be persisted.

examples/kubernetes/dind-docker.yaml

@@ -0,0 +1,78 @@
+kind: PersistentVolumeClaim
+apiVersion: v1
+metadata:
+  name: act-runner-vol
+spec:
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 1Gi
+  storageClassName: standard
+---
+apiVersion: v1
+data:
+  token: << base64 encoded registration token >>
+kind: Secret
+metadata:
+  name: runner-secret
+type: Opaque
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  labels:
+    app: act-runner
+  name: act-runner
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: act-runner
+  strategy: {}
+  template:
+    metadata:
+      creationTimestamp: null
+      labels:
+        app: act-runner
+    spec:
+      restartPolicy: Always
+      volumes:
+      - name: docker-certs
+        emptyDir: {}
+      - name: runner-data
+        persistentVolumeClaim:
+          claimName: act-runner-vol
+      containers:
+      - name: runner
+        image: gitea/act_runner:nightly
+        command: ["sh", "-c", "while ! nc -z localhost 2376 </dev/null; do echo 'waiting for docker daemon...'; sleep 5; done; /sbin/tini -- /opt/act/run.sh"]
+        env:
+        - name: DOCKER_HOST
+          value: tcp://localhost:2376
+        - name: DOCKER_CERT_PATH
+          value: /certs/client
+        - name: DOCKER_TLS_VERIFY
+          value: "1"
+        - name: GITEA_INSTANCE_URL
+          value: http://gitea-http.gitea.svc.cluster.local:3000
+        - name: GITEA_RUNNER_REGISTRATION_TOKEN
+          valueFrom:
+            secretKeyRef:
+              name: runner-secret
+              key: token
+        volumeMounts:
+        - name: docker-certs
+          mountPath: /certs
+        - name: runner-data
+          mountPath: /data
+      - name: daemon
+        image: docker:23.0.6-dind
+        env:
+        - name: DOCKER_TLS_CERTDIR
+          value: /certs
+        securityContext:
+          privileged: true
+        volumeMounts:
+        - name: docker-certs
+          mountPath: /certs