We can virtualize even GUI Text Editor with Docker

#docker #emacs #linux

Recently, I virtualized almost everything with Docker.

Finally I virtualized my Emacs with GUI because I am using Arch Linux which cannot provide emacs-mozc and fcitx-mozc for package namespace collision.

So I installed Emacs with X11 client in Docker container, then display Emacs screen to Host's X11 server.

Environment

Host OS：Arch Linux
Guest OS：Debian GNU/Linux
Docker version： 1.12.1

Procedure

First of all, write quite simple Dockerfile. Hopefully install some tools like emacs-mozc or cask.

FROM debian:latest

RUN apt-get update
RUN apt-get -y install emacs24

RUN useradd -G sudo -u 1000 --create-home emacs

ENV HOME /home/emacs
WORKDIR /home/emacs

CMD /usr/bin/emacs --reverse

Then run docker build --tag emacs . in the directory with above Dockerfile.

Next, create a launch script and put it to a directory. $PATH must include the directory.

#!/bin/bash

xhost +local:
docker run -it --rm \
       -v /tmp/.X11-unix:/tmp/.X11-unix \
       -v $HOME:/home/emacs/host_home \
       -e DISPLAY=$DISPLAY \
       --user 1000 \
       emacs

xhost -local:

The above code just do

Pass $DISPLAY env var to the container
Share $HOME directory for general usage
Share /tmp/.X11-unix between host and container to connect X11 socket

Finally launch emacs:

emacs-docker

It works!

To check the host and guest interaction let's run dired emacs file explorer.

Yes, $HOME of host is mounted to the container.
In the container these files owner are recognized as Docker executing user(emacs). cause the UID 1000 matches.

Attention

If HOST UID and GUEST UID does not match, we cannot edit files for permission problem.
We cannot use Symbolic link in the container like Docker, LXC. This is sometimes really inconvenient.

This post is a kind of joke to some extent, but I will use emacs-docker actively.