user-dockerfiles

This repository contains a set of miscellaneous high-level Dockerfiles and Docker Compose configuration files.

Docker Compose

Installation instructions for Docker Compose can be found in the official documentation.

What is Docker Compose?

Compose is a tool for defining and running multi-container Docker applications. With Compose, you use a YAML file to configure your application’s services. Then, with a single command, you create and start all the services from your configuration [1].

Docker Compose is used by following a three-step process:

1. define a Dockerfile;
2. create a configuration file named docker-compose.yml;
3. and run the docker-compose up command in the directory of the YAML file.

Docker Compose configuration file

Important: While the Compose file format have surpassed version 3, we are currently required to use version 2.3 in order to gain access to the runtime configuration key (see NVIDIA Docker FAQ).

In general, a Compose configuration file is a listing of named services, each with their own set of configuration keys. Below is a typical configuration file used by this repository:

version: '2.3'

services:
  myservice:
    image: myimage
    command: ["/bin/bash"]
    environment:
      - NVIDIA_VISIBLE_DEVICES=0
    ports:
      - "<local port>:<container port>"
    restart: always
    runtime: nvidia
    stdin_open: true
    tty: true
    volumes:
      - "<local volume>:<container volume>"

The list if services is found under the top-level key services; here we have a single service called myservice. Inside the individual service, configuration keys are used to define what a service is. Here is an explanation of the keys we have used:

• image : name of the Docker image that should run for this service.
• command : startup command. Here, the Unix shell Bash will run.
• environment : a list of environment variables. NVIDIA_VISIBLE_DEVICES is used to isolate GPUs with the help of GPU device minor numbers. In our case the GPU numbered 0 will be made available in the Docker container formed by this service.
• ports : a list of exposed ports.
• restart : restart policy, where no is the default policy. always ensures that Compose always attempts to restart the service(s), for example, after a reboot. Please refer to the restart documentation.
• runtime : key available in version 2.3 that enables us to specify the NVIDIA runtime.
• stdin_open and tty: must be set to true to use an interactive shell (similar to -it with docker run).
• volumes : a list of shared volumes.

Do note that Compose YAML files can either have the .yml or .yaml extension.

Running Docker Compose

With a docker-compose.yml file ready, Docker Compose can be run using the docker-compose up command in the directory of the configuration file.

In many situations it is useful to run the docker-compose up command in "detached" mode with the -d option, so that the services are correctly daemonized.

A daemonized Docker container (-d) can be accessed by issuing docker attach like so:

docker attach <container id>

The Docker container ID can be found by running docker ps or docker-compose ps.

To detach from a container without stopping it you can type the escape sequence Ctrl-p + Ctrl-q (see Docker attach documentation).

Running containers can be stopped without removal by running docker-compose stop [SERVICE...], and stopped containers can be started by running docker-compose start [SERVICE...] (see stop documentation).

Stopping containers and removing containers, networks, volumes, and images created by docker-compose up can be done by running docker-compose down (see down documentation).

See the full list of command-line references for more information.