Installing with Docker¶
Evennia releases docker images as part of regular commits and releases. This makes running an Evennia-based game in a Docker container easy.
First, install the
docker program so you can run the Evennia container. You can get it freely from docker.com. Linux users can likely also get it through their normal package manager.
To fetch the latest evennia docker image, run:
docker pull evennia/evennia
This will get the latest stable image.
docker pull evennia/evennia:develop
gets the image based off Evennia’s unstable
cd to a place where your game dir is, or where you want to create it. Then run:
docker run -it --rm -p 4000:4000 -p 4001:4001 -p 4002:4002 --rm -v $PWD:/usr/src/game --user $UID:$GID evennia/evennia
Having run this (see next section for a description of what’s what), you will be at a prompt inside the docker container:
evennia|docker /usr/src/game $
This is a normal shell prompt. We are in the
/usr/src/game location inside the docker container. If you had anything in the folder you started from, you should see it here (with
ls) since we mounted the current directory to
-v above). You have the
evennia command available and can now proceed to create a new game as per the normal game setup instructions (no virtualenv needed).
You can run Evennia from inside this container if you want to, it’s like you are root in a little
isolated Linux environment. To exit the container and all processes in there, press
Ctrl-D. If you
created a new game folder, you will find that it has appeared on-disk.
The game folder or any new files that you created from inside the container will appear as owned by
root. If you want to edit the files outside of the container you should change the ownership. On Linux/Mac you do this with
sudo chown myname:myname -R mygame, where you replace
mynamewith your username and
mygamewith whatever your game folder is named.
Below is an explanation of the
docker run command we used:
docker run ... evennia/evenniatells us that we want to run a new container based on the
evennia/evenniadocker image. Everything in between are options for this. The
evennia/evenniais the name of our official docker image on the dockerhub repository. If you didn’t do
docker pull evennia/evenniafirst, the image will be downloaded when running this, otherwise your already downloaded version will be used. It contains everything needed to run Evennia.
-ithas to do with creating an interactive session inside the container we start.
--rmwill make sure to delete the container when it shuts down. This is nice to keep things tidy on your drive.
-p 4000:4000 -p 4001:4001 -p 4002:4002means that we map ports
4002from inside the docker container to same-numbered ports on our host machine. These are ports for telnet, webserver and websockets. This is what allows your Evennia server to be accessed from outside the container (such as by your MUD client)!
-v $PWD:/usr/src/gamemounts the current directory (outside the container) to the path
/usr/src/gameinside the container. This means that when you edit that path in the container you will actually be modifying the “real” place on your hard drive. If you didn’t do this, any changes would only exist inside the container and be gone if we create a new one. Note that in linux a shortcut for the current directory is
$PWD. If you don’t have this for your OS, you can replace it with the full path to the current on-disk directory (like
C:/Development/evennia/gameor wherever you want your evennia files to appear).
--user $UID:$GIDensures the container’s modifications to
$PWDare done with you user and group IDs instead of root’s IDs (root is the user running evennia inside the container). This avoids having stale
.pidfiles in your filesystem between container reboots which you have to force delete with
sudo rm server/*.pidbefore each boot.
Running your game as a docker image¶
If you run the
docker command given in the previous section from your game dir you can then easily start Evennia and have a running server without any further fuss.
But apart from ease of install, the primary benefit to running an Evennia-based game in a container is to simplify its deployment into a public production environment. Most cloud-based hosting providers these days support the ability to run container-based applications. This makes deploying or updating your game as simple as building a new container image locally, pushing it to your Docker Hub account, and then pulling from Docker Hub into your AWS/Azure/other docker-enabled hosting account. The container eliminates the need to install Python, set up a virtualenv, or run pip to install dependencies.
Start Evennia and run through docker¶
For remote or automated deployment you may want to start Evennia immediately as soon as the docker container comes up. If you already have a game folder with a database set up you can also start the docker container and pass commands directly to it. The command you pass will be the main process to run in the container. From your game dir, run for example this command:
docker run -it --rm -p 4000:4000 -p 4001:4001 -p 4002:4002 --rm -v $PWD:/usr/src/game evennia/evennia evennia start -l
This will start Evennia as the foreground process, echoing the log to the terminal. Closing the
terminal will kill the server. Note that you must use a foreground command like
evennia start -l
evennia ipstart to start the server - otherwise the foreground process will finish immediately
and the container go down.
Create your own game image¶
These steps assume that you have created or otherwise obtained a game directory already. First,
cd to your game dir and create a new empty text file named
Dockerfile. Save the following two lines into it:
FROM evennia/evennia:latest ENTRYPOINT evennia start -l
These are instructions for building a new docker image. This one is based on the official
evennia/evennia image, but also makes sure to start evennia when it runs (so we don’t need to
enter it and run commands).
To build the image:
docker build -t mydhaccount/mygame .
(don’t forget the period at the end, it will use the
Dockerfile from the current location). Here
mydhaccount is the name of your
dockerhub account. If you don’t have a dockerhub account you can build the image locally only (name the container whatever you like in that case, like just
Docker images are stored centrally on your computer. You can see which ones you have available locally with
docker images. Once built, you have a couple of options to run your game.
Run container from your game image for development¶
To run the container based on your game image locally for development, mount the local game directory as before:
docker run -it --rm -p 4000:4000 -p 4001:4001 -p 4002:4002 -v $PWD:/usr/src/game --user $UID:$GID mydhaccount/mygame
Evennia will start and you’ll get output in the terminal, perfect for development. You should be able to connect to the game with your clients normally.
Deploy game image for production¶
Each time you rebuild the docker image as per the above instructions, the latest copy of your game
directory is actually copied inside the image (at
/usr/src/game/). If you don’t mount your on-disk
folder there, the internal one will be used. So for deploying evennia on a server, omit the
option and just give the following command:
docker run -it --rm -d -p 4000:4000 -p 4001:4001 -p 4002:4002 --user $UID:$GID mydhaccount/mygame
Your game will be downloaded from your docker-hub account and a new container will be built using the image and started on the server! If your server environment forces you to use different ports, you can just map the normal ports differently in the command above.
Above we added the
-d option, which starts the container in daemon mode - you won’t see any
return in the console. You can see it running with
$ docker ps CONTAINER ID IMAGE COMMAND CREATED ... f6d4ca9b2b22 mygame "/bin/sh -c 'evenn..." About a minute ago ...
Note the container ID, this is how you manage the container as it runs.
docker logs f6d4ca9b2b22
Looks at the STDOUT output of the container (i.e. the normal server log)
docker logs -f f6d4ca9b2b22
Tail the log (so it updates to your screen ‘live’).
docker pause f6d4ca9b2b22
Suspend the state of the container.
docker unpause f6d4ca9b2b22
Un-suspend it again after a pause. It will pick up exactly where it were.
docker stop f6d4ca9b2b22
Stop the container. To get it up again you need to use
docker run, specifying ports etc. A new
container will get a new container id to reference.
How it Works¶
evennia/evennia docker image holds the evennia library and all of its dependencies. It also has an
ONBUILD directive which is triggered during builds of images derived from it. This
ONBUILD directive handles setting up a volume and copying your game directory code into the proper location within the container.
In most cases, the Dockerfile for an Evennia-based game will only need the
FROM evennia/evennia:latest directive, and optionally a
MAINTAINER directive if you plan to publish your image on Docker Hub and would like to provide contact info.
For more information on Dockerfile directives, see the Dockerfile Reference.
For more information on volumes and Docker containers, see the Docker site’s Manage data in containers page.
What if I Don’t Want “LATEST”?¶
evennia/evennia image is built automatically whenever there is a new commit to the
main branch of Evennia. It is possible to create your own custom evennia base docker image based on any arbitrary commit.
Use git tools to checkout the commit that you want to base your image upon. (In the example below, we’re checking out commit a8oc3d5b.)
git checkout -b my-stable-branch a8oc3d5b
Change your working directory to the
Dockerfile. Note that
Dockerfilehas changed over time, so if you are going far back in the commit history you might want to bring a copy of the latest
Dockerfilewith you and use that instead of whatever version was used at the time.
docker buildcommand to build the image based off of the currently checked out commit. The example below assumes your docker account is mydhaccount.
docker build -t mydhaccount/evennia .
Now you have a base evennia docker image built off of a specific commit. To use this image to build your game, you would modify FROM directive in the Dockerfile for your game directory to be:
Note: From this point, you can also use the
docker tag command to set a specific tag on your image and/or upload it into Docker Hub under your account.
5. At this point, build your game using the same
docker build command as usual. Change your
working directory to be your game directory and run
docker build -t mydhaccountt/mygame .
Additional Creature Comforts¶
The Docker ecosystem includes a tool called
docker-compose, which can orchestrate complex multi- container applications, or in our case, store the default port and terminal parameters that we want specified every time we run our container. A sample
docker-compose.yml file to run a containerized Evennia game in development might look like this:
version: '2' services: evennia: image: mydhacct/mygame stdin_open: true tty: true ports: - "4001-4002:4001-4002" - "4000:4000" volumes: - .:/usr/src/game
With this file in the game directory next to the
Dockerfile, starting the container is as simple as
For more information about
docker-compose, see Getting Started with docker-
Note that with this setup you lose the
--user $UIDoption. The problem is that the variable
UIDis not available inside the configuration file
docker-compose.yml. A workaround is to hardcode your user and group id. In a terminal run
echo $UID:$GIDand if for example you get
1000:1000you can add to
user: 1000:1000just below the