Run systemd inside a pod on Kubernetes

systemd-pod-kubernetes.md

Quick test on how to run systemd inside a pod on Kubernetes

based from https://developers.redhat.com/blog/2016/09/13/running-systemd-in-a-non-privileged-container/

Create container image:

FROM opensuse/tumbleweed:latest
RUN zypper install -y systemd systemd-sysvinit
CMD ["/sbin/init"]

Create Deployment:

Use a serviceAccount with privileged PSP in order to use hostPath.

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: systemd
  namespace: default
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: psp:systemd:privileged
  namespace: default
roleRef:
  kind: ClusterRole
  name: suse:caasp:psp:privileged
  apiGroup: rbac.authorization.k8s.io
subjects:
- kind: ServiceAccount
  name: systemd
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: systemd
  namespace: default
  labels:
    app: systemd
spec:
  replicas: 1
  selector:
    matchLabels:
      app: systemd
  template:
    metadata:
      labels:
        app: systemd
    spec:
      containers:
      - name: systemd
        image: localhost/opensuse-systemd:latest
        imagePullPolicy: IfNotPresent
        stdin: true
        tty: true
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
          limits:
            cpu: 200m
            memory: 200Mi
        #terminationGracePeriodSeconds: 10
        volumeMounts:
        - mountPath: /run
          name: tmpfs-run
        - mountPath: /sys/fs/cgroup
          name: cgroup
          readOnly: true
      serviceAccount: systemd
      volumes:
      - name: tmpfs-run
        emptyDir:
          medium: Memory
      - name: cgroup
        hostPath:
          path: /sys/fs/cgroup
          type: DirectoryOrCreate

Then I just did a quick try zypper in nginx curl && systemctl start nginx && curl localhost