Snapd in Docker

snapd
13

Thanks @ogra. This is working:

$ cat Dockerfile
FROM ubuntu:16.04
ENV container docker
ENV PATH /snap/bin:$PATH
ADD snap /usr/local/bin/snap
RUN apt-get update
RUN apt-get install -y snapd squashfuse fuse
RUN systemctl enable snapd
STOPSIGNAL SIGRTMIN+3
CMD [ "/sbin/init" ]

And:

$ cat snap
#!/bin/sh -e

while ! kill -0 $(pidof snapd) 2>/dev/null; do
  echo "Waiting for snapd to start."
  sleep 1
done

/usr/bin/snap $@

$ chmod +x snap

Now, build it:

$ docker build -t snapd .

Run it:

$  docker run --name=snapd -ti -d \                                                                                     
  --tmpfs /run --tmpfs /run/lock --tmpfs /tmp \
  --privileged \ # [1]
  -v /lib/modules:/lib/modules:ro \ # [2]
  snapd

And install some snaps:

$ docker exec -it snapd snap install emoj
$ docker exec -it snapd emoj success
✔  ✅  ☑  📚  👌  🎓  💰

Notes:

  1. Otherwise systemd complains about /sys not being writable when reloading udev rules (ConditionPathIsReadWrite=/sys was not met)

  2. Otherwise strictly confined snaps fail to execute:
    $ docker exec -it snapd emoj
    cannot perform operation: mount --rbind /lib/modules /tmp/snap.rootfs_NCx2ET//lib/modules: No such file or directory

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