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:

To check the version, enter kubectl version.

Install Kompose

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

Kompose is released via GitHub on a three-week cycle, you can see all current releases on the GitHub release page.

  1. # Linux
  2. curl -L https://github.com/kubernetes/kompose/releases/download/v1.26.0/kompose-linux-amd64 -o kompose
  4. # macOS
  5. curl -L https://github.com/kubernetes/kompose/releases/download/v1.26.0/kompose-darwin-amd64 -o kompose
  7. # Windows
  8. curl -L https://github.com/kubernetes/kompose/releases/download/v1.26.0/kompose-windows-amd64.exe -o kompose.exe
  10. chmod +x kompose
  11. sudo mv ./kompose /usr/local/bin/kompose

Alternatively, you can download the tarball.

Installing using go get pulls from the master branch with the latest development changes.

  1. go get -u github.com/kubernetes/kompose

Kompose is in EPEL CentOS repository. If you don’t have EPEL repository already installed and enabled you can do it by running sudo yum install epel-release.

If you have EPEL enabled in your system, you can install Kompose like any other package.

  1. sudo yum -y install kompose

Kompose is in Fedora 24, 25 and 26 repositories. You can install it like any other package.

  1. sudo dnf -y install kompose

On macOS you can install the latest release via Homebrew:

  1. 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.

    1. version: "2"
    3. services:
    5.   redis-master:
    6.     image: registry.k8s.io/redis:e2e
    7.     ports:
    8.       - "6379"
    10.   redis-slave:
    11.     image: gcr.io/google_samples/gb-redisslave:v3
    12.     ports:
    13.       - "6379"
    14.     environment:
    15.       - GET_HOSTS_FROM=dns
    17.   frontend:
    18.     image: gcr.io/google-samples/gb-frontend:v4
    19.     ports:
    20.       - "80:80"
    21.     environment:
    22.       - GET_HOSTS_FROM=dns
    23.     labels:
    24.       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>.

    1. kompose convert

    The output is similar to:

    1. INFO Kubernetes file "frontend-tcp-service.yaml" created 
    2. INFO Kubernetes file "redis-master-service.yaml" created 
    3. INFO Kubernetes file "redis-slave-service.yaml" created 
    4. INFO Kubernetes file "frontend-deployment.yaml" created 
    5. INFO Kubernetes file "redis-master-deployment.yaml" created 
    6. INFO Kubernetes file "redis-slave-deployment.yaml" created
    1.  kubectl apply -f frontend-tcp-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:

    1. service/frontend-tcp created
    2. service/redis-master created
    3. service/redis-slave created
    4. deployment.apps/frontend created
    5. deployment.apps/redis-master created
    6. 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:

    1. minikube service frontend

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

    1. kubectl describe svc frontend
    1. Name:                     frontend-tcp
    2. Namespace:                default
    3. Labels:                   io.kompose.service=frontend-tcp
    4. Annotations:              kompose.cmd: kompose convert
    5.                           kompose.service.type: LoadBalancer
    6.                           kompose.version: 1.26.0 (40646f47)
    7. Selector:                 io.kompose.service=frontend
    8. Type:                     LoadBalancer
    9. IP Family Policy:         SingleStack
    10. IP Families:              IPv4
    11. IP:                       10.43.67.174
    12. IPs:                      10.43.67.174
    13. Port:                     80  80/TCP
    14. TargetPort:               80/TCP
    15. NodePort:                 80  31254/TCP
    16. Endpoints:                10.42.0.25:80
    17. Session Affinity:         None
    18. External Traffic Policy:  Cluster
    19. Events:
    20.   Type    Reason                Age   From                Message
    21.   ----    ------                ----  ----                -------
    22.   Normal  EnsuringLoadBalancer  62s   service-controller  Ensuring load balancer
    23.   Normal  AppliedDaemonSet      62s   service-controller  Applied LoadBalancer DaemonSet kube-system/svclb-frontend-tcp-9362d276

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

    1. curl http://192.0.2.89

  4. Clean-up.

    After you are finished testing out the example application deployment, simply run the following command in your shell to delete the resources used.

    1. kubectl delete -f frontend-tcp-service.yaml,redis-master-service.yaml,redis-slave-service.yaml,frontend-deployment.yaml,redis-master-deployment.yaml,redis-slave-deployment.yaml

User Guide

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

  1. kompose --file docker-voting.yml convert
  1. WARN Unsupported key networks - ignoring
  2. WARN Unsupported key build - ignoring
  3. INFO Kubernetes file "worker-svc.yaml" created
  4. INFO Kubernetes file "db-svc.yaml" created
  5. INFO Kubernetes file "redis-svc.yaml" created
  6. INFO Kubernetes file "result-svc.yaml" created
  7. INFO Kubernetes file "vote-svc.yaml" created
  8. INFO Kubernetes file "redis-deployment.yaml" created
  9. INFO Kubernetes file "result-deployment.yaml" created
  10. INFO Kubernetes file "vote-deployment.yaml" created
  11. INFO Kubernetes file "worker-deployment.yaml" created
  12. INFO Kubernetes file "db-deployment.yaml" created
  1. ls
  1. db-deployment.yaml  docker-compose.yml         docker-gitlab.yml  redis-deployment.yaml  result-deployment.yaml  vote-deployment.yaml  worker-deployment.yaml
  2. 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:

  1. kompose -f docker-compose.yml -f docker-guestbook.yml convert
  1. INFO Kubernetes file "frontend-service.yaml" created         
  2. INFO Kubernetes file "mlbparks-service.yaml" created         
  3. INFO Kubernetes file "mongodb-service.yaml" created          
  4. INFO Kubernetes file "redis-master-service.yaml" created     
  5. INFO Kubernetes file "redis-slave-service.yaml" created      
  6. INFO Kubernetes file "frontend-deployment.yaml" created      
  7. INFO Kubernetes file "mlbparks-deployment.yaml" created      
  8. INFO Kubernetes file "mongodb-deployment.yaml" created       
  9. INFO Kubernetes file "mongodb-claim0-persistentvolumeclaim.yaml" created
  10. INFO Kubernetes file "redis-master-deployment.yaml" created  
  11. INFO Kubernetes file "redis-slave-deployment.yaml" created
  1. ls
  1. mlbparks-deployment.yaml  mongodb-service.yaml                       redis-slave-service.jsonmlbparks-service.yaml  
  2. frontend-deployment.yaml  mongodb-claim0-persistentvolumeclaim.yaml  redis-master-service.yaml
  3. frontend-service.yaml     mongodb-deployment.yaml                    redis-slave-deployment.yaml
  4. 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

  1. kompose --provider openshift --file docker-voting.yml convert
  1. WARN [worker] Service cannot be created because of missing port.
  2. INFO OpenShift file "vote-service.yaml" created             
  3. INFO OpenShift file "db-service.yaml" created               
  4. INFO OpenShift file "redis-service.yaml" created            
  5. INFO OpenShift file "result-service.yaml" created           
  6. INFO OpenShift file "vote-deploymentconfig.yaml" created    
  7. INFO OpenShift file "vote-imagestream.yaml" created         
  8. INFO OpenShift file "worker-deploymentconfig.yaml" created  
  9. INFO OpenShift file "worker-imagestream.yaml" created       
  10. INFO OpenShift file "db-deploymentconfig.yaml" created      
  11. INFO OpenShift file "db-imagestream.yaml" created           
  12. INFO OpenShift file "redis-deploymentconfig.yaml" created   
  13. INFO OpenShift file "redis-imagestream.yaml" created        
  14. INFO OpenShift file "result-deploymentconfig.yaml" created  
  15. 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.

  1. kompose --provider openshift --file buildconfig/docker-compose.yml convert
  1. WARN [foo] Service cannot be created because of missing port.
  2. INFO OpenShift Buildconfig using git@github.com:rtnpro/kompose.git::master as source.
  3. INFO OpenShift file "foo-deploymentconfig.yaml" created     
  4. INFO OpenShift file "foo-imagestream.yaml" created          
  5. INFO OpenShift file "foo-buildconfig.yaml" created

Note: If you are manually pushing the OpenShift artifacts using oc create -f, you need to ensure that you push the imagestream artifact before the buildconfig artifact, to workaround this OpenShift issue: https://github.com/openshift/origin/issues/4518 .

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.

  1. kompose convert -j
  2. INFO Kubernetes file "redis-svc.json" created
  3. INFO Kubernetes file "web-svc.json" created
  4. INFO Kubernetes file "redis-deployment.json" created
  5. INFO Kubernetes file "web-deployment.json" created

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

  1. kompose convert --replication-controller
  2. INFO Kubernetes file "redis-svc.yaml" created
  3. INFO Kubernetes file "web-svc.yaml" created
  4. INFO Kubernetes file "redis-replicationcontroller.yaml" created
  5. 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.

  1. kompose convert --daemon-set
  2. INFO Kubernetes file "redis-svc.yaml" created
  3. INFO Kubernetes file "web-svc.yaml" created
  4. INFO Kubernetes file "redis-daemonset.yaml" created
  5. 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:

  1. kompose convert -c
  1. INFO Kubernetes file "web-svc.yaml" created
  2. INFO Kubernetes file "redis-svc.yaml" created
  3. INFO Kubernetes file "web-deployment.yaml" created
  4. INFO Kubernetes file "redis-deployment.yaml" created
  5. chart created in "./docker-compose/"
  1. tree docker-compose/
  1. docker-compose
  2. ├── Chart.yaml
  3. ├── README.md
  4. └── templates
  5.     ├── redis-deployment.yaml
  6.     ├── redis-svc.yaml
  7.     ├── web-deployment.yaml
  8.     └── 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:

    1. version: "2"
    2. services:
    3.   nginx:
    4.     image: nginx
    5.     dockerfile: foobar
    6.     build: ./foobar
    7.     cap_add:
    8.       - ALL
    9.     container_name: foobar
    10.     labels:
    11.       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:

    1. version: "2"
    2. services:
    3.   web:
    4.     image: tuna/docker-counter23
    5.     ports:
    6.     - "5000:5000"
    7.     links:
    8.     - redis
    9.     labels:
    10.       kompose.service.expose: "counter.example.com"
    11.   redis:
    12.     image: redis:3.0
    13.     ports:
    14.     - "6379"

The currently supported options are:

KeyValue
kompose.service.typenodeport / clusterip / loadbalancer
kompose.service.exposetrue / hostname

Note: The kompose.service.type label should be defined with ports only, otherwise kompose will fail.

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.

docker-compose restartobject createdPod restartPolicy
“”controller objectAlways
alwayscontroller objectAlways
on-failurePodOnFailure
noPodNever

Note: The controller object could be deployment or replicationcontroller.

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

  1. version: '2'
  3. services:
  4.   pival:
  5.     image: perl
  6.     command: ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
  7.     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.