Docker in Miget Container

The following example demonstrates how to run Docker-in-DockerMiget (Kata) Container.

Note

Miget's PaaS utilizes Kata Containers with virtfs as a storage bridge between the host system and the container runtime.

What does this mean?

Since virtfs doesn't work well with overlayfs, a workaround is needed. We use a sparse image file mounted as an ext4 file system under /var/lib/docker. Please refer to the entrypoint.sh file for more details.

To ensure this setup works, mount a block device under /data with sufficient available disk space.

Build

To build your app, simply create one, assign it to your Miget (compute resource), and push your changes using git push miget. That's it!

Run

Once the app is deployed on Miget, you can enter your app's shell and check the Docker setup by running the following command:

/ # docker info
Client:
 Version:    27.2.0
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.16.2
    Path:     /usr/local/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.29.2
    Path:     /usr/local/libexec/docker/cli-plugins/docker-compose

Server:
 Containers: 1
  Running: 0
  Paused: 0
  Stopped: 1
 Images: 1
 Server Version: 27.2.0
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: true
  Native Overlay Diff: false
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Cgroup Version: 1
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 472731909fa34bd7bc9c087e4c27943f9835f111
 runc version: v1.1.13-0-g58aa920
 init version: de40ad0
 Security Options:
  seccomp
   Profile: builtin
 Kernel Version: 6.1.62
 Operating System: Alpine Linux v3.20 (containerized)
 OSType: linux
 Architecture: x86_64
 CPUs: 2
 Total Memory: 742.1MiB
 ID: dee50a10-16e4-4051-955b-d02f56e38588
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false
 Product License: Community Engine

WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled