Running containers with kubedock

Kubedock is a minimal container engine implementation that gives you a Podman-/docker-like experience inside a Che workspace. Kubedock is especially useful when dealing with ad-hoc, ephemeral, and testing containers, such as in the use cases listed below:

  • Executing application tests which rely on Testcontainers framework.

  • Using Quarkus Dev Services.

  • Running a container stored in remote container registry, for local development purposes

The image you want to use with kubedock must be compliant with Openshift Container Platform guidelines. Otherwise, running the image with kubedock will result in a failure even if the same image runs locally without issues.
Enabling kubedock

After enabling the kubedock environment variable, kubedock will run the following podman commands:

  • podman run

  • podman ps

  • podman exec

  • podman cp

  • podman logs

  • podman inspect

  • podman kill

  • podman rm

  • podman wait

  • podman stop

  • podman start

Other commands such as podman build are started by the local Podman.

Using podman commands with kubedock has following limitations

  • The podman build -t <image> . && podman run <image> command will fail. Use podman build -t <image> . && podman push <image> && podman run <image> instead.

  • The podman generate kube command is not supported.

  • --env option causes the podman run command to fail.
Prerequisites
Process

  • Add KUBEDOCK_ENABLED=true environment variable to the devfile.

    • (OPTIONAL) Use the KUBEDOCK_PARAM variable to specify additional kubedock parameters. The list of variables is available here. Alternatively, you can use the following command to view the available options:

      # kubedock server --help
Example
schemaVersion: 2.2.0
metadata:
  name: kubedock-sample-devfile
components:
  - name: tools
    container:
      image: quay.io/devfile/universal-developer-image:latest
      memoryLimit: 8Gi
      memoryRequest: 1Gi
      cpuLimit: "2"
      cpuRequest: 200m
      env:
        - name: KUBEDOCK_PARAMS
          value: "--reverse-proxy --kubeconfig /home/user/.kube/config --initimage quay.io/agiertli/kubedock:0.13.0"
        - name: USE_JAVA17
          value: "true"
        - value: /home/jboss/.m2
          name: MAVEN_CONFIG
        - value: -Xmx4G -Xss128M -XX:MetaspaceSize=1G -XX:MaxMetaspaceSize=2G
          name: MAVEN_OPTS
        - name: KUBEDOCK_ENABLED
          value: 'true'
        - name: DOCKER_HOST
          value: 'tcp://127.0.0.1:2475'
        - name: TESTCONTAINERS_RYUK_DISABLED
          value: 'true'
        - name: TESTCONTAINERS_CHECKS_DISABLE
          value: 'true'
      endpoints:
        - exposure: none
          name: kubedock
          protocol: tcp
          targetPort: 2475
        - exposure: public
          name: http-booster
          protocol: http
          targetPort: 8080
          attributes:
            discoverable: true
            urlRewriteSupported: true
        - exposure: internal
          name: debug
          protocol: http
          targetPort: 5005
      volumeMounts:
        - name: m2
          path: /home/user/.m2
  - name: m2
    volume:
      size: 10G

You must configure the Podman or docker API to point to kubedock setting CONTAINER_HOST=tcp://127.0.0.1:2475 or DOCKER_HOST=tcp://127.0.0.1:2475 when running containers.

At the same time, you must configure Podman to point to local Podman when building the container.