Deploy multiple containers on a single host

A YAML file defining version (DEPRECATED), services (REQUIRED), networks, volumes, configs and secrets

Default path is compose.yaml (or compose.yml, docker-compose.yaml, docker-compose.yml) in working directory

1. Build an image from local

2. Compose containers

version: "3.9" # version of Docker Compose
services:
  webapp: # container
    image: lchenlangley/count # image name [domain/image:tag]
    build: . # search local, if image does not exist, build image from local
    ports:
      - 8000:5000 # host port : container port
    environment:
      - MYREDIS_HOST=redisserver # environment variable
  redisserver: # container
    image: redis:alpine # if image exist in local, use the local image
# a bridge network is created by default
        

1. Fetch images from repositories

2. Compose containers

version: "3.9"
services:
  webapp:
    image: lchenlangley/count # fetch image from Docker Hub
    ports:
      - 8000:5000
    environment:
      - MYREDIS_HOST=redisserver
  redisserver:
    image: "redis:alpine" # fetch image from Docker Hub
        

# compose_1.yaml
version: "3.9"
services:
  webapp: # container
    image: lchenlangley/count
    #build: .
    volumes:
      - type: volume
        source: voltemp
        target: /code
volumes:
  voltemp:
        

# compose_2.yaml
version: "3.9"
services:
  webapp: # container
    ports:
      - target: 5000
        published: 8000
        protocol: tcp
        mode: host
    environment:
      MYREDIS_HOST: redisserver
  redisserver: # container
    image: redis:alpine
        

docker-compose -f compose_1.yaml -f compose_2.yaml up
docker-compose -f compose_1.yaml -f compose_2.yaml down
        

re-use a common configuration

# compose.yaml
version: "3.9"
services:
  webapp: # container
    extends:
      file: common.yaml
      service: template
    image: lchenlangley/count
    #build: .
    volumes:
      - type: volume
        source: voltemp
        target: /code
  redisserver: # container
    image: redis:alpine
volumes:
  voltemp:
        

# common.yaml, contains a common configuration
version: "3.9"
services:
  template: # container
    ports:
      - target: 5000
        published: 8000
        protocol: tcp
        mode: host
    environment:
      MYREDIS_HOST: redisserver
        

docker-compose up
docker-compose down
        

Abstract concept implementing docker run

image

• Specifies the image to start the container from

image: redis # [domainName/imageName:tag]
        

ports

• Expose ports from container to host

ports:
      - 8000:5000 # host_port:container_port
        

build

• Build image from local source code, allow to miss the image attribute

services:
  webapp:
    image: awesome/webapp # image name
    build: . # path for source code and Dockerfile
        

services:
  webapp:
    image: awesome/database # image name
    build:
        context: . # source code path
        dockerfile: ../Dockerfile # Dockerfile path
        

services:
  webapp:
    build: . # source code path
        

environment

• Add environment variables

services:
  webapp:
    ...
    environment:
       MYREDIS_HOST: redisserver
        

services:
  webapp:
    ...
    environment:
       - MYREDIS_HOST=redisserver
        

networks

• Specify the networks to join

services:
  webapp:
    ...
    networks:
     - frontend-network
     - backend-network
        

restart

• restart containers when restarting the docker daemon, rebooting your server, using a CMD inside a container and running an exit, etc.
• restart policy is ignored when containers are stopped manually, such as stop and kill by docker-compose

restart: always
        

env_file

• Add environment variables from a file, not really work in the test

# .env, default environment file
MYREDIS_HOST=redisserver
 
# compose.yml
services:
  webapp:
    ...
    environment:
       - MYREDIS_HOST=${MYREDIS_HOST}
        

# env/webapp.env
MYREDIS_HOST=redisserver
 
# compose.yml
services:
  webapp:
    ...
    environment:
       - MYREDIS_HOST=${MYREDIS_HOST}
 
# compose
docker-compose --env-file env/webapp.env up
 
# turn off compose
docker-compose --env-file env/webapp.env down
        

profiles and depends_on

• Selectively enable services
• If unassigned, the service is always started
• If assigned, the service is only started if the profile is activated

services:
  foo:
    image: foo
  bar:
    image: bar
    profiles:
      - test
  baz:
    image: baz
    depends_on:
      - bar
    profiles:
      - test
  zot:
    image: zot
    depends_on:
      - bar
    profiles:
      - debug
        

# enable test (bar, baz) and foo
docker-compose --profile test up
 
# invalid, profile debug (zot) is enabled, but zot depends on bar which is in the profile test
docker-compose --profile debug up
 
# enable test(bar, baz), debug(zot) and foo
docker-compose --profile debug --profile test up
 
# enable bar, profile test is active, but baz is not enabled
docker-compose up bar
 
# enable baz, profile test is active, bar is enabled by depends_on constraint
docker-compose up baz
 
# enable zot and test, bar is enabled by depends_on constraint
docker-compose --profile test up zot
		

command

• Override the default command of a container

command: python app.py
        

expose

• Specify the port number exposed from container
• Same as expose in Dockerfile, it functions as a type of documentation
• By default, make the access port number in app, the expose number in dockerfile, and the expose port number in compose file match

expose:
  - "5000"
        

container_name

• Specify container name instead of using default name

container_name: redis-container
        

hostname

• Specify host name inside a container

hostname: redis-host
        

Capability abstraction to establish an IP route between containers, analogous to docker network create

By default, docker-compose sets up a single network, containers join the network for communication

• [directory]_default, network name

version: "3.9"
services:
  webapp: # container
    image: lchenlangley/count
    #build: .
    volumes:
      - type: volume
        source: voltemp
        target: /code
    ports:
      - target: 5000
        published: 8000
        protocol: tcp
        mode: host
    environment:
      MYREDIS_HOST: ${MYREDIS_HOST}
    networks:
      - app-net
  redisserver: # container
    image: redis:alpine
    networks:
      - app-net
volumes:
  voltemp:
networks:
  app-net: # create a network named [directory]_app-net
		

Analogous to docker volume create

Volume

# Short Syntax
services:
  app:
    # ...
    volumes: # volumes for a particular service
      - [source]:[target]:[mode]
        # source, named volume, defined in the top level "volumes"
        # target, an absolute path in container
        # mode, read-only or read-write
 
volumes: # define volumes
		

version: "3.9"
services:
  webapp:
    image: lchenlangley/count
    build: .
    ports:
      - 8000:5000
    volumes:
      - voltemp:/code
    environment:
      - MYREDIS_HOST=redisserver
      - FLASK_ENV=development
    depends_on:
      - redisserver
  redisserver:
    image: "redis:alpine"
volumes:
  voltemp: # volume name length should greater than five
        

# Syntax
services:
  app:
    # ...
    volumes: # volumes for a particular service
      - type: volume
        source: [volume_name]
        target: [path]
 
volumes: # define volumes
        

version: "3.9"
services:
  webapp:
    image: lchenlangley/count
    build: .
    ports:
      - 8000:5000
    volumes:
      - type: volume
        source: voltemp
        target: /code
    environment:
      - MYREDIS_HOST=redisserver
      - FLASK_ENV=development
    depends_on:
      - redisserver
  redisserver:
    image: "redis:alpine"
volumes:
  voltemp:
        

Bind Mount

# Short Syntax
services:
  app:
    # ...
    volumes: # volumes for a particular service
      - [source]:[target]:[mode]
        # source, a path (absolute or relate)
        # target, an absolute path in container
        # mode, read-only or read-write
        

version: "3.9"
services:
  webapp:
    image: lchenlangley/count
    build: .
    ports:
      - 8000:5000
    volumes:
      - .:/code
    environment:
      - MYREDIS_HOST=redisserver
      - FLASK_ENV=development
    depends_on:
      - redisserver
  redisserver:
    image: "redis:alpine"
        

# Syntax
services:
  app:
    # ...
    volumes: # volumes for a particular service
      - type: bind
        source: [path]
        target: [path]
        

version: "3.9"
services:
  webapp:
    image: lchenlangley/count
    build: .
    ports:
      - 8000:5000
    volumes:
      - type: bind
        source: .
        target: /code
    environment:
      - MYREDIS_HOST=redisserver
      - FLASK_ENV=development
    depends_on:
      - redisserver
  redisserver:
    image: "redis:alpine"
        

Grant access to configs on a per-service basis

Grant access to secrets on a per-service basis

2 services, backed by Docker images: webapp and database

1 secret (HTTPS certificate), injected into the frontend

1 configuration (HTTP), injected into the frontend

1 persistent volume, attached to the backend

2 networks: front-tier and back-tier

services:
  frontend:
    image: awesome/webapp
    ports:
      - "443:8043"
    networks:
      - front-tier
      - back-tier
    configs:
      - httpd-config
    secrets:
      - server-certificate
 
  backend:
    image: awesome/database
    volumes:
      - db-data:/etc/data
    networks:
      - back-tier
 
volumes:
  db-data:
    driver: flocker
    driver_opts:
      size: "10GiB"
 
configs:
  httpd-config:
    external: true
 
secrets:
  server-certificate:
    external: true
 
networks:
  # The presence of these objects is sufficient to define them
  front-tier: {}
  back-tier: {}
		

# get command help
docker-compose --help
 
# start services
# --build, build images from source code instead of loading built images before starting containers
# -d, detached
# docker-compose up [service list]
 
docker-compose up # start all services
docker-compose up webapp # start service webapp
docker-compose -f [composeFileName] up # specify compose file
 
# turn off and remove services
docker-compose down
 
# build images in compose file
docker-compose build
 
# list images of the current compose
docker-compose images
 
# list service of the current compose
docker-compose ps
 
# stop services of the current compose
docker-compose stop [serviceName] # stop a specific service
docker-compose stop # stop services in the current compose
 
# start services
docker-compose start [serviceName] # start a specific service
docker-compose start # start services in the current compose
 
# one-off command
# docker-compose run [serviceName] [command]
docker-compose run webapp env
 
# view the compose file
docker-compose config
		

Docker Compose Tutorial: advanced Docker made simple

docker-compose CLI

Compose File Reference

The Compose Specification

User Guide