comkube

Comkube: Deploy Docker Compose Apps on Kubernetes

Keep your Compose files but deploy them on Kubernetes.

Prerequisites

• Docker
• kubectl (includes kustomize)

Usage

We assume:

• You already have your compose.yaml (or docker-compose.yaml) file.
• Your kubectl uses the desired kubeconfig context.

First, we need the following extra files in the same folder as your compose.yaml:

1. File kustomization.yaml is the entry point for the kustomize tool, which can generate and transform Kubernetes manifests:

   generators:
     - my-k8s-compose-app.yaml
   

2. File my-k8s-compose-app.yaml is the bridge to your compose.yaml; it tells kustomize to use the plugin Comkube (run in a container):

   apiVersion: comkube.evolutics.info/v1alpha1
   kind: ComposeApp
   metadata:
     name: my-app
     annotations:
       config.kubernetes.io/function: |
         container:
           image: ghcr.io/evolutics/comkube:0.2.0
           mounts:
             - type: bind
               src: compose.yaml
               dst: /srv/compose.yaml
   

That's it. Now you are ready to deploy your Compose app to Kubernetes for real:

cd folder/with/above/files/
kubectl kustomize --enable-alpha-plugins . | kubectl apply --filename -

kubectl kustomize --enable-alpha-plugins . converts your Compose file into Kubernetes manifests and prints the result (to stdout). Then kubectl apply --filename - applies these manifests (given on stdin), that is, it creates or updates the corresponding Kubernetes objects.

Config reference

Related projects

If you need to convert your Compose files to Kubernetes manifest files once, from then on maintaining those Kubernetes manifests, then use Kompose directly. Comkube uses Kompose underneath.

TODO

• Consider pruning using kubectl ApplySet.
• Distribute kubectl plugin with Krew.
• Document Podman support.
• Provide kubectl plugin.