Translate a Docker Compose File to Kubernetes Resources

What's Kompose? It's a conversion tool for all things compose (namely Docker Compose) to container orchestrators (Kubernetes or OpenShift).

More information can be found on the Kompose website at http://kompose.io.

Before you begin

You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:

• Killercoda
• Play with Kubernetes

Install Kompose

We have multiple ways to install Kompose. Our preferred method is downloading the binary from the latest GitHub release.

• GitHub download
• Build from source
• CentOS package
• Fedora package
• Homebrew (macOS)

# Linux
curl -L https://github.com/kubernetes/kompose/releases/download/v1.26.0/kompose-linux-amd64 -o kompose

# macOS
curl -L https://github.com/kubernetes/kompose/releases/download/v1.26.0/kompose-darwin-amd64 -o kompose

# Windows
curl -L https://github.com/kubernetes/kompose/releases/download/v1.26.0/kompose-windows-amd64.exe -o kompose.exe

chmod +x kompose
sudo mv ./kompose /usr/local/bin/kompose

go get -u github.com/kubernetes/kompose

sudo yum -y install kompose

sudo dnf -y install kompose

brew install kompose

Use Kompose

In a few steps, we'll take you from Docker Compose to Kubernetes. All you need is an existing docker-compose.yml file.

1. Go to the directory containing your docker-compose.yml file. If you don't have one, test using this one.

   version: "2"
   
   services:
   
     redis-master:
       image: registry.k8s.io/redis:e2e
       ports:
         - "6379"
   
     redis-slave:
       image: gcr.io/google_samples/gb-redisslave:v3
       ports:
         - "6379"
       environment:
         - GET_HOSTS_FROM=dns
   
     frontend:
       image: gcr.io/google-samples/gb-frontend:v4
       ports:
         - "80:80"
       environment:
         - GET_HOSTS_FROM=dns
       labels:
         kompose.service.type: LoadBalancer
   

2. To convert the docker-compose.yml file to files that you can use with kubectl, run kompose convert and then kubectl apply -f <output file>.

   kompose convert
   

   The output is similar to:

   INFO Kubernetes file "frontend-service.yaml" created
      INFO Kubernetes file "frontend-service.yaml" created
   INFO Kubernetes file "frontend-service.yaml" created
   INFO Kubernetes file "redis-master-service.yaml" created
      INFO Kubernetes file "redis-master-service.yaml" created
   INFO Kubernetes file "redis-master-service.yaml" created
   INFO Kubernetes file "redis-slave-service.yaml" created
      INFO Kubernetes file "redis-slave-service.yaml" created
   INFO Kubernetes file "redis-slave-service.yaml" created
   INFO Kubernetes file "frontend-deployment.yaml" created
      INFO Kubernetes file "frontend-deployment.yaml" created
   INFO Kubernetes file "frontend-deployment.yaml" created
   INFO Kubernetes file "redis-master-deployment.yaml" created
      INFO Kubernetes file "redis-master-deployment.yaml" created
   INFO Kubernetes file "redis-master-deployment.yaml" created
   INFO Kubernetes file "redis-slave-deployment.yaml" created
      INFO Kubernetes file "redis-slave-deployment.yaml" created
   INFO Kubernetes file "redis-slave-deployment.yaml" created
   

    kubectl apply -f frontend-service.yaml,redis-master-service.yaml,redis-slave-service.yaml,frontend-deployment.yaml,redis-master-deployment.yaml,redis-slave-deployment.yaml
   

   The output is similar to:

   service/frontend created
   service/redis-master created
   service/redis-slave created
   deployment.apps/frontend created
   deployment.apps/redis-master created
   deployment.apps/redis-slave created
   

   Your deployments are running in Kubernetes.

3. Access your application.

   If you're already using minikube for your development process:

   minikube service frontend
   

   Otherwise, let's look up what IP your service is using!

   kubectl describe svc frontend
   

   Name:                   frontend
   Namespace:              default
   Labels:                 service=frontend
   Selector:               service=frontend
   Type:                   LoadBalancer
   IP:                     10.0.0.183
   LoadBalancer Ingress:   192.0.2.89
   Port:                   80      80/TCP
   NodePort:               80      31144/TCP
   Endpoints:              172.17.0.4:80
   Session Affinity:       None
   No events.
   

   If you're using a cloud provider, your IP will be listed next to LoadBalancer Ingress.

   curl http://192.0.2.89
   

User Guide

• CLI
  • kompose convert
• Documentation
  • Alternative Conversions
  • Labels
  • Restart
  • Docker Compose Versions

Kompose has support for two providers: OpenShift and Kubernetes. You can choose a targeted provider using global option --provider. If no provider is specified, Kubernetes is set by default.

kompose convert

Kompose supports conversion of V1, V2, and V3 Docker Compose files into Kubernetes and OpenShift objects.

Kubernetes kompose convert example

kompose --file docker-voting.yml convert

WARN Unsupported key networks - ignoring
WARN Unsupported key build - ignoring
INFO Kubernetes file "worker-svc.yaml" created
INFO Kubernetes file "db-svc.yaml" created
INFO Kubernetes file "redis-svc.yaml" created
INFO Kubernetes file "result-svc.yaml" created
INFO Kubernetes file "vote-svc.yaml" created
INFO Kubernetes file "redis-deployment.yaml" created
INFO Kubernetes file "result-deployment.yaml" created
INFO Kubernetes file "vote-deployment.yaml" created
INFO Kubernetes file "worker-deployment.yaml" created
INFO Kubernetes file "db-deployment.yaml" created

ls

db-deployment.yaml  docker-compose.yml         docker-gitlab.yml  redis-deployment.yaml  result-deployment.yaml  vote-deployment.yaml  worker-deployment.yaml
db-svc.yaml         docker-voting.yml          redis-svc.yaml     result-svc.yaml        vote-svc.yaml           worker-svc.yaml

You can also provide multiple docker-compose files at the same time:

kompose -f docker-compose.yml -f docker-guestbook.yml convert

INFO Kubernetes file "frontend-service.yaml" created         
INFO Kubernetes file "mlbparks-service.yaml" created         
INFO Kubernetes file "mongodb-service.yaml" created          
INFO Kubernetes file "redis-master-service.yaml" created     
INFO Kubernetes file "redis-slave-service.yaml" created      
INFO Kubernetes file "frontend-deployment.yaml" created      
INFO Kubernetes file "mlbparks-deployment.yaml" created      
INFO Kubernetes file "mongodb-deployment.yaml" created       
INFO Kubernetes file "mongodb-claim0-persistentvolumeclaim.yaml" created
INFO Kubernetes file "redis-master-deployment.yaml" created  
INFO Kubernetes file "redis-slave-deployment.yaml" created   

ls

mlbparks-deployment.yaml  mongodb-service.yaml                       redis-slave-service.jsonmlbparks-service.yaml  
frontend-deployment.yaml  mongodb-claim0-persistentvolumeclaim.yaml  redis-master-service.yaml
frontend-service.yaml     mongodb-deployment.yaml                    redis-slave-deployment.yaml
redis-master-deployment.yaml

When multiple docker-compose files are provided the configuration is merged. Any configuration that is common will be overridden by subsequent file.

OpenShift kompose convert example

kompose --provider openshift --file docker-voting.yml convert

WARN [worker] Service cannot be created because of missing port.
INFO OpenShift file "vote-service.yaml" created             
INFO OpenShift file "db-service.yaml" created               
INFO OpenShift file "redis-service.yaml" created            
INFO OpenShift file "result-service.yaml" created           
INFO OpenShift file "vote-deploymentconfig.yaml" created    
INFO OpenShift file "vote-imagestream.yaml" created         
INFO OpenShift file "worker-deploymentconfig.yaml" created  
INFO OpenShift file "worker-imagestream.yaml" created       
INFO OpenShift file "db-deploymentconfig.yaml" created      
INFO OpenShift file "db-imagestream.yaml" created           
INFO OpenShift file "redis-deploymentconfig.yaml" created   
INFO OpenShift file "redis-imagestream.yaml" created        
INFO OpenShift file "result-deploymentconfig.yaml" created  
INFO OpenShift file "result-imagestream.yaml" created  

It also supports creating buildconfig for build directive in a service. By default, it uses the remote repo for the current git branch as the source repo, and the current branch as the source branch for the build. You can specify a different source repo and branch using --build-repo and --build-branch options respectively.

kompose --provider openshift --file buildconfig/docker-compose.yml convert

WARN [foo] Service cannot be created because of missing port.
INFO OpenShift Buildconfig using [email protected]:rtnpro/kompose.git::master as source.
INFO OpenShift file "foo-deploymentconfig.yaml" created     
INFO OpenShift file "foo-imagestream.yaml" created          
INFO OpenShift file "foo-buildconfig.yaml" created

Alternative Conversions

The default kompose transformation will generate Kubernetes Deployments and Services, in yaml format. You have alternative option to generate json with -j. Also, you can alternatively generate Replication Controllers objects, Daemon Sets, or Helm charts.

kompose convert -j
INFO Kubernetes file "redis-svc.json" created
INFO Kubernetes file "web-svc.json" created
INFO Kubernetes file "redis-deployment.json" created
INFO Kubernetes file "web-deployment.json" created

The *-deployment.json files contain the Deployment objects.

kompose convert --replication-controller
INFO Kubernetes file "redis-svc.yaml" created
INFO Kubernetes file "web-svc.yaml" created
INFO Kubernetes file "redis-replicationcontroller.yaml" created
INFO Kubernetes file "web-replicationcontroller.yaml" created

The *-replicationcontroller.yaml files contain the Replication Controller objects. If you want to specify replicas (default is 1), use --replicas flag: kompose convert --replication-controller --replicas 3.

kompose convert --daemon-set
INFO Kubernetes file "redis-svc.yaml" created
INFO Kubernetes file "web-svc.yaml" created
INFO Kubernetes file "redis-daemonset.yaml" created
INFO Kubernetes file "web-daemonset.yaml" created

The *-daemonset.yaml files contain the DaemonSet objects.

If you want to generate a Chart to be used with Helm run:

kompose convert -c

INFO Kubernetes file "web-svc.yaml" created
INFO Kubernetes file "redis-svc.yaml" created
INFO Kubernetes file "web-deployment.yaml" created
INFO Kubernetes file "redis-deployment.yaml" created
chart created in "./docker-compose/"

tree docker-compose/

docker-compose
├── Chart.yaml
├── README.md
└── templates
    ├── redis-deployment.yaml
    ├── redis-svc.yaml
    ├── web-deployment.yaml
    └── web-svc.yaml

The chart structure is aimed at providing a skeleton for building your Helm charts.

Labels

kompose supports Kompose-specific labels within the docker-compose.yml file in order to explicitly define a service's behavior upon conversion.

• kompose.service.type defines the type of service to be created.

  For example:

  version: "2"
  services:
    nginx:
      image: nginx
      dockerfile: foobar
      build: ./foobar
      cap_add:
        - ALL
      container_name: foobar
      labels:
        kompose.service.type: nodeport
  

• kompose.service.expose defines if the service needs to be made accessible from outside the cluster or not. If the value is set to "true", the provider sets the endpoint automatically, and for any other value, the value is set as the hostname. If multiple ports are defined in a service, the first one is chosen to be the exposed.

  • For the Kubernetes provider, an ingress resource is created and it is assumed that an ingress controller has already been configured.
  • For the OpenShift provider, a route is created.

  For example:

  version: "2"
  services:
    web:
      image: tuna/docker-counter23
      ports:
      - "5000:5000"
      links:
      - redis
      labels:
        kompose.service.expose: "counter.example.com"
    redis:
      image: redis:3.0
      ports:
      - "6379"
  

The currently supported options are:

Restart

If you want to create normal pods without controllers you can use restart construct of docker-compose to define that. Follow table below to see what happens on the restart value.

For example, the pival service will become pod down here. This container calculated value of pi.

version: '2'

services:
  pival:
    image: perl
    command: ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
    restart: "on-failure"

Warning about Deployment Configurations

If the Docker Compose file has a volume specified for a service, the Deployment (Kubernetes) or DeploymentConfig (OpenShift) strategy is changed to "Recreate" instead of "RollingUpdate" (default). This is done to avoid multiple instances of a service from accessing a volume at the same time.

If the Docker Compose file has service name with _ in it (for example, web_service), then it will be replaced by - and the service name will be renamed accordingly (for example, web-service). Kompose does this because "Kubernetes" doesn't allow _ in object name.

Please note that changing service name might break some docker-compose files.

Docker Compose Versions

Kompose supports Docker Compose versions: 1, 2 and 3. We have limited support on versions 2.1 and 3.2 due to their experimental nature.

A full list on compatibility between all three versions is listed in our conversion document including a list of all incompatible Docker Compose keys.