docs/Servers/Containerization/Kubernetes/Migrating Docker-Compose.yml to k8s.md

Migrating Docker Stack to Rancher RKE2 Kubernetes Cluster

You may be comfortable operating with Portainer or docker-compose, but there comes a point where you might want to migrate those existing workloads to a Kubernetes cluster as easily-as-possible. Lucklily, there is a way to do this using a tool called "Kompose'. Follow the instructions seen below to convert and deploy your existing docker-compose.yml into a Kubernetes cluster such as Rancher RKE2.

Installing Kompose

The first step involves downloading Kompose from https://kompose.io/installation. Once you have it downloaded and installed onto your environment of choice, save a copy of your docker-compose.yml file somewhere on-disk, then open up a terminal and run the following command:

kompose --file docker-compose.yaml convert --stdout > compose-k8s.yaml

This will attempt to convert the docker-compose.yml file into a Kubernetes manifest YAML file. The Before and after example can be seen below:

=== "docker-compose.yml`"

version: "2.1"
services:
  ntfy:
    image: binwiederhier/ntfy
    container_name: ntfy
    command:
      - serve
    environment:
      - NTFY_ATTACHMENT_CACHE_DIR=/var/lib/ntfy/attachments
      - NTFY_BASE_URL=https://ntfy.bunny-lab.io
      - TZ=America/Denver    # optional: Change to your desired timezone
    #user: UID:GID # optional: Set custom user/group or uid/gid
    volumes:
      - /srv/containers/ntfy/cache:/var/cache/ntfy
      - /srv/containers/ntfy/etc:/etc/ntfy
    ports:
      - 80:80
    restart: always
    networks:
        docker_network:
          ipv4_address: 192.168.5.45

networks:
  default:
    external:
      name: docker_network
  docker_network:
    external: true

=== "compose-k8s.yaml"

---
apiVersion: v1
kind: Service
metadata:
  annotations:
    kompose.cmd: C:\ProgramData\chocolatey\lib\kubernetes-kompose\tools\kompose.exe --file ntfy.yaml convert --stdout
    kompose.version: 1.37.0 (fb0539e64)
  labels:
    io.kompose.service: ntfy
  name: ntfy
spec:
  ports:
    - name: "80"
      port: 80
      targetPort: 80
  selector:
    io.kompose.service: ntfy

---
apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    kompose.cmd: C:\ProgramData\chocolatey\lib\kubernetes-kompose\tools\kompose.exe --file ntfy.yaml convert --stdout
    kompose.version: 1.37.0 (fb0539e64)
  labels:
    io.kompose.service: ntfy
  name: ntfy
spec:
  replicas: 1
  selector:
    matchLabels:
      io.kompose.service: ntfy
  strategy:
    type: Recreate
  template:
    metadata:
      annotations:
        kompose.cmd: C:\ProgramData\chocolatey\lib\kubernetes-kompose\tools\kompose.exe --file ntfy.yaml convert --stdout
        kompose.version: 1.37.0 (fb0539e64)
      labels:
        io.kompose.service: ntfy
    spec:
      containers:
        - args:
            - serve
          env:
            - name: NTFY_ATTACHMENT_CACHE_DIR
              value: /var/lib/ntfy/attachments
            - name: NTFY_BASE_URL
              value: https://ntfy.bunny-lab.io
            - name: TZ
              value: America/Denver
          image: binwiederhier/ntfy
          name: ntfy
          ports:
            - containerPort: 80
              protocol: TCP
          volumeMounts:
            - mountPath: /var/cache/ntfy
              name: ntfy-claim0
            - mountPath: /etc/ntfy
              name: ntfy-claim1
      restartPolicy: Always
      volumes:
        - name: ntfy-claim0
          persistentVolumeClaim:
            claimName: ntfy-claim0
        - name: ntfy-claim1
          persistentVolumeClaim:
            claimName: ntfy-claim1

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  labels:
    io.kompose.service: ntfy-claim0
  name: ntfy-claim0
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 100Mi

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  labels:
    io.kompose.service: ntfy-claim1
  name: ntfy-claim1
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 100Mi