Docker in a GKE sandbox

Docker is a platform designed to help developers build, share, and run container applications.

In gVisor, all basic docker commands should function as expected. The host network driver and the bridge network driver are tested and supported.

How to run Docker in a GKE Sandbox

First, install a GKE standard cluster (1.29.0 or higher) and deploy a node pool with gVisor enabled. You can view the full documentation here.

You could also run docker in gVisor at GKE autopilot cluster, the GKE version needs to be 1.32 or higher. When creating the autopilot cluster, please add the option --workload-policies=allow-net-admin to allow NET_ADMIN capability that will be granted by the gVisor sandbox.

An example command to start an GKE autopilot cluster will be:

gcloud container clusters create-auto [CLUTER_NAME] --workload-policies=allow-net-admin --location=[LOCATION] --cluster-version=1.32.2-gke.1182001

gVisor sandbox doesn’t need any extra capabilities from the host to run docker inside gVisor, the listed capabilities are granted by gVisor to the docker daemon that is running inside sandbox.

Prepare a container image with pre-installed Docker:

$ docker build -t docker-in-gvisor images/basic/docker
$ docker push {registry_url}/docker-in-gvisor:latest

Create a Kubernetes pod YAML file (docker.yaml) with the following content:

apiVersion: v1
kind: Pod
metadata:
  name: docker-in-gvisor
spec:
  runtimeClassName: gvisor
  containers:
  - name: docker-in-gvisor
    image: {registry_url}/docker-in-gvisor:latest
    securityContext:
      capabilities:
        add: [AUDIT_WRITE,CHOWN,DAC_OVERRIDE,FOWNER,FSETID,KILL,MKNOD,NET_BIND_SERVICE,NET_RAW,SETFCAP,SETGID,SETPCAP,SETUID,SYS_CHROOT,SYS_PTRACE,NET_ADMIN,SYS_ADMIN]
    volumeMounts:
      - name: docker
        mountPath: /var/lib/docker
  volumes:
  - name: docker
    emptyDir: {}

This YAML file defines a Kubernetes Pod named docker-in-gvisor that will run a single container from the avagin/docker-in-gvisor:0.1 image.

Apply the pod YAML to your GKE cluster using the kubectl apply command:

$ kubectl apply -f docker.yaml

Verify that the docker-in-gvisor pid is running successfully: shell $ kubectl get pods | grep docker-in-gvisor

You can access the container by executing a shell inside it. Use the following command:

kubectl exec -it docker-in-gvisor -- bash

Now, we can build and run Docker containers.

$ mkdir whalesay && cd whalesay
$ cat > Dockerfile <<EOF
FROM ubuntu

RUN apt-get update && apt-get install -y cowsay curl
RUN mkdir -p /usr/share/cowsay/cows/
RUN curl -o /usr/share/cowsay/cows/docker.cow https://raw.githubusercontent.com/docker/whalesay/master/docker.cow
ENTRYPOINT ["/usr/games/cowsay", "-f", "docker.cow"]
EOF
$ docker build -t whalesay .
....
Successfully tagged whalesay:latest
$ docker run -it --rm whalesay "Containers do not contain, but gVisor-s do!"
 _________________________________________
/ Containers do not contain, but gVisor-s \
\ do!                                     /
 -----------------------------------------
   \               ##         .
    \        ## ## ##        ==
          ## ## ## ##       ===
       /""""""""""""""""\___/ ===
  ~~~ {~~ ~~~~ ~~~ ~~~~ ~~ ~ /  ===- ~~~
       \______ o          __/
         \    \        __/
          \____\______/

For GKE autopilot, please use docker build --network=host -t whalesay . Running with bridge network driver in GKE autopilot is not fully supported.