docker-compose

version: '3'
services:
  container: # this is not the same as container name
	container_name: name # must be defined here, especially in a stack, otherwise it will be named based on the current folder
	ports:
	  - 1234:1234/tcp
	environment:
	  - PUID=1000 # define environment variable in this format
	volumes:
	  - /host/path:/container/path
	restart: unless-stopped

A basic docker-compose in home settings will consists of service name (container), container_name (name), ports (1234), networks, volumes, environments(PUID) and restart (unless-stopped).

version: '3'
services:
  my-ubuntu: # name = folder-name-my-ubuntu
    image: ubuntu:latest
  my-nginx:
    image: nginx 
    name: compose-nginx # name = compose-nginx

• In this example, the container name would be folder-name-my-ubuntu and folder-name-my-nginx
• Must need to define it under container name for the desired name.

Networking

Adding Container to Custom Network

    networks:
      - net1
      - net2 # attaching to multiple networks
      - default

• multiple networks can be specified as a list
• when a container is in multiple networks, it will have multiple interfaces with multiple IP addresses
• when specifying default in networks, this is the default network that docker compose will create, eg. folder-name_default

Additional Options for each network:

• when specifying additional options with multiple networks, list cannot work

    networks:
      net-1:
      net-2:
        ipv4_address: 192.168.120.254

• ipv4_address is specify custom IP address as long as it’s in correct subnet

Network Definition

YAML

networks:
  public:
    name: public
    ipam:
      config:
        - subnet: 192.168.120.0/24
          gateway: 192.168.120.1

• however, when defined as such, the network cannot be removed if there is active container, and when changing network configurations
  External

networks:
  net1:
    name: net1
    external: true

• the external: true specify that the network is managed outside of compose and already exists

Volumes

Environments

docker compose config will print out the file with all the environment variables present

environments

    environment:
      - PUID=1000
      - SHELL=${SHELL}
      TZ: "America/Vancouver"

• the environment can be set as a list X=y or a dictionary X: 2
• it can also consist of shell variables with ${} syntax
  • $ default value if such variable is unset, similar to bash-variables
• environment variables will take precedence over env_file
  Command substitution such as $(id -u) does not work, consider using system variables
  The commands also work from non-env keys

	user: ${PUID:-1000}:${PGID:-1000}

• when starting the container it will run with PUID/PGID defined in shell variables
• it’s a good idea to export these in bashrc for seamless deployment

env_file

    env_file:
      - secret.env
      - ../folder/config.env

• using env_file key, the files are provided at list
• the file’s location can be given as relative position or in another folder
• the file that is defined first will take precedence if duplicate arise

Long Strings

For multiline strings use | and for single line strings use >

multiline: |
	this should be multiple lines
singleline: >
	this is all in one line

The strings has to be indented correctly.

Interactive

    stdin_open: true
    tty: true

This is equivalent to docker run -it