Every agent in Byte Arena runs isolated in its own Docker container.
Dockerfile file is required at the root of your project in order to build your container and to deploy your agent.
Sample Node.js Dockerfile
While your agent can be coded in whatever programming language you like, here is an example Dockerfile using the official Node.js (version 7) image:
FROM node:7 ENV NPM_CONFIG_LOGLEVEL error # /usr/app is the root of our code in the container WORKDIR /usr/app # Bundle our source code in the container COPY . /usr/app/ # Install dependencies RUN npm install # Build the source RUN npm run build # Tell Docker how to run our code CMD [ "npm", "start" ]
As you can see, it’s a pretty basic Dockerfile, bundling and compiling the source inside the container.
- These lines tell Docker to run our code inside a container featuring NodeJS 7, and sets to
errorthe verbosity level for
npm, the Node package manager
FROM node:7 ENV NPM_CONFIG_LOGLEVEL error
- We tell Docker that the commands of the Dockerfile will be executed in this folder.
- Our agent source code is copied inside the container, in
COPY . /usr/app/
- We use
npmto install the NPM dependencies of our agent inside the container
RUN npm install
- We then “build” the agent code, using Babel to transpile our ES6 code to ES5 code runnable by NodeJS.
RUN npm run build
- We finally tell Docker what command to issue to run our code when the container launches.
CMD [ "npm", "start" ]
Environment variables passed to the container
These environment variables are set on agent containers by Byte Arena:
HOST: the network host where the Byte Arena game server is running and reachable by the agent
PORT: the port number where the agent must connect on the game server
AGENTID: the agent random ID in use for the duration of a game
Constraints on the container
In a container, network is restricted; agents are not be able to connect to the internet, or communicate directly with other agents.
The only network communications allowed are with the game server.
Allowed Docker intructions
For security reason, you can only use the following instructions in your Dockerfile:
All other Docker instructions are banned (
PORT, etc.). Your container won’t be allowed on the online Byte Arena platform if your Dockerfile uses banned instructions.
The container uses a read-only ephemeral filesystem.
All Unix Capabilities are dropped and your container is not privileged.
You are not allowed to change the Unix user or group which will execute your program.
nobody must be present in the container in order to run your program. Note that most Linux distribution have it out of the box.