anki/docs/docker/README.md

# Anki in Docker

This is an example of how you can build and run Anki from inside Docker. This
approach keeps everything inside Docker images, and sends the GUI to an X11
display over TCP/IP. This approach keeps things tidy, so may be a good choice
for if you wish to build Anki irregularly and don't want to build it outside of
Docker.

It takes longer to build after small changes however, so for development, if you
wish to use Docker, the approach [in the build
scripts](../../scripts/docker/README.md) may be more appropriate.

# Build the Docker image

For best results, enable BuildKit (`export DOCKER_BUILDKIT=1`).

When in this current directory, one can build the Docker image like this:

```bash
docker build --tag anki --file Dockerfile ../../
```

When this is done, run `docker image ls` to see that the image has been created.

If one wants to build from the project's root directory, use this command:

```bash
docker build --tag anki --file docs/docker/Dockerfile .
```

# Run the Docker image

Anki starts a graphical user interface, and this requires some extra setup on the user's
end. These instructions were tested on Linux (Debian 11) and will have to be adapted for
other operating systems.

To allow the Docker container to pull up a graphical user interface, we need to run the
following:

```bash
xhost +local:root
```

Once done using Anki, undo this with

```bash
xhost -local:root
```

Then, we will construct our `docker run` command:

```bash
docker run --rm -it \
    --name anki \
    --volume $HOME/.local/share:$HOME/.local/share:rw \
    --volume /etc/passwd:/etc/passwd:ro \
    --user $(id -u):$(id -g) \
    --volume /tmp/.X11-unix:/tmp/.X11-unix:rw \
    --env DISPLAY=$DISPLAY \
    anki
```

Here is a breakdown of some of the arguments:

-   Mount the current user's `~/.local/share` directory onto the container. Anki saves things
    into this directory, and if we don't mount it, we will lose any changes once the
    container exits. We mount this as read-write (`rw`) because we want to make changes here.

    ```bash
    --volume $HOME/.local/share:$HOME/.local/share:rw
    ```

-   Mount `/etc/passwd` so we can enter the container as ourselves. We mount this as
    read-only because we definitely do not want to modify this.

    ```bash
    --volume /etc/passwd:/etc/passwd:ro
    ```

-   Enter the container with our user ID and group ID, so we stay as ourselves.

    ```bash
    --user $(id -u):$(id -g)
    ```

-   Mount the X11 directory that allows us to open displays.

    ```bash
    --volume /tmp/.X11-unix:/tmp/.X11-unix:rw
    ```

-   Pass the `DISPLAY` variable to the container, so it knows where to display graphics.

    ```bash
    --env DISPLAY=$DISPLAY
    ```

# Running Dockerized Anki easily from the command line

One can create a shell function that executes the `docker run` command. Then one can
simply run `anki` on the command line, and Anki will open in Docker. Make sure to change
the image name to whatever you used when building Anki.

```bash
anki() {
    docker run --rm -it \
        --name anki \
        --volume $HOME/.local/share:$HOME/.local/share:rw \
        --volume /etc/passwd:/etc/passwd:ro \
        --user $(id -u):$(id -g) \
        --volume /tmp/.X11-unix:/tmp/.X11-unix:rw \
        --env DISPLAY=$DISPLAY \
        anki "$@"
}
```