ZNC for Docker

Run the ZNC IRC Bouncer in a Docker container.

Prerequisites

1. Install Docker.

Running

ZNC needs to store settings somewhere, so simplest way to run it is to mount a directory from the host machine to /znc-data in the container:

mkdir -p $HOME/.znc
docker run -d -p 6667 -v $HOME/.znc:/znc-data jimeh/znc

This will download the image if needed, and create a default config file in your data directory unless you already have a config in place. The default config has ZNC listening on port 6667. To see which port on the host has been exposed:

docker ps

Or if you want to specify which port to map the default 6667 port to:

docker run -d -p 36667:6667 -v $HOME/.znc:/znc-data jimeh/znc

Resulting in port 36667 on the host mapping to 6667 within the container.

Configuring ZNC

If you've let the container create a default config for you, the default username/password combination is admin/admin. You can access the web-interface to create your own user by pointing your web-browser at the opened port.

For example, if you passed in -p 36667:6667 like above when running the container, the web-interface would be available on: http://hostname:36667/

I'd recommend you create your own user by cloning the admin user, then ensure your new cloned user is set to be an admin user. Once you login with your new user go ahead and delete the default admin user.

External Modules

If you need to use external modules, simply place the original *.cpp source files for the modules in your {DATADIR}/modules directory. The startup script will automatically build all .cpp files in that directory with znc-buildmod every time you start the container.

This ensures that you can easily add new external modules to your znc configuration without having to worry about building them. And it only slows down ZNC's startup with a few seconds.

DATADIR

ZNC stores all it's settings in a Docker volume mounted to /znc-data inside the container.

Mount a Host Directory

The simplest approach is typically to mount a directory off of your host machine into the container. This is done with -v $HOME/.znc:/znc-data like in the example above.

One issue with this though is that ZNC needs to run as it's own user within the container, the directory will have it's ownership changed to UID 1000 (user) and GID 1000 (group). Meaning after the first run, you might need root access to manually modify the data directory.

Use a Volume Container

First we need to create a volume container:

docker run -v /znc-data --name znc-data busybox echo "data for znc"

And then run the znc container using the --volumes-from option instead of -v:

docker run -d -p 6667 --name znc --volumes-from znc-data jimeh/znc

You'll want to periodically back up your znc data to the host:

docker run --volumes-from znc-data -v $(pwd):/backup ubuntu tar cvf /backup/backup.tar /znc-data

And restore them later:

docker run --volumes-from znc-data -v $(pwd):/backup busybox tar xvf /backup/backup.tar

Passing Custom Arguments to ZNC

As docker run passes all arguments after the image name to the entrypoint script, the start-znc script simply passes all arguments along to ZNC.

For example, if you want to use the --makepass option, you would run:

docker run -i -t -v $HOME/.znc:/znc-data jimeh/znc --makepass

Make note of the use of -i and -t instead of -d. This attaches us to the container, so we can interact with ZNC's makepass process. With -d it would simply run in the background.

A note about ZNC 1.6

Starting with version 1.6, ZNC now requires ssl/tls certificate verification! This means that it will not connect to your IRC server(s) if they don't present a valid certificate. This is meant to help keep you safer from MitM attacks.

This image installs the debian/ubuntu ca-certificates package so that servers with valid certificates will automatically be connected to ensuring no additional user intervention needed. If one of your servers doesn't have a valid fingerprint, you will need to connect to your bouncer and respond to *status.

See this article for more information.

Building It Yourself

1. Follow Prerequisites above.
2. Checkout source: git clone https://github.com/jimeh/docker-znc.git && cd docker-znc
3. Build container: sudo docker build -t $(whoami)/znc .
4. Run container: sudo docker run -d -p 6667 -v $HOME/.znc:/znc-data $(whoami)/znc