compose/docs/yml.md

layout	title
default	fig.yml reference

fig.yml reference

Each service defined in fig.yml must specify exactly one of image or build. Other keys are optional, and are analogous to their docker run command-line counterparts.

As with docker run, options specified in the Dockerfile (e.g. CMD, EXPOSE, VOLUME, ENV) are respected by default - you don't need to specify them again in fig.yml.

###image

Tag or partial image ID. Can be local or remote - Fig will attempt to pull if it doesn't exist locally.

image: ubuntu
image: orchardup/postgresql
image: a4bc65fd

build

Path to a directory containing a Dockerfile. Fig will build and tag it with a generated name, and use that image thereafter.

build: /path/to/build/dir

command

Override the default command.

command: bundle exec thin -p 3000

links

Link to containers in another service. Either specify both the service name and the link alias (SERVICE:ALIAS), or just the service name (which will also be used for the alias).

links:
 - db
 - db:database
 - redis

An entry with the alias' name will be created in /etc/hosts inside containers for this service, e.g:

172.17.2.186  db
172.17.2.186  database
172.17.2.187  redis

Environment variables will also be created - see the environment variable reference for details.

ports

Expose ports. Either specify both ports (HOST:CONTAINER), or just the container port (a random host port will be chosen).

Note: When mapping ports in the HOST:CONTAINER format, you may experience erroneous results when using a container port lower than 60, because YAML will parse numbers in the format xx:yy as sexagesimal (base 60). For this reason, we recommend always explicitly specifying your port mappings as strings.

ports:
 - "3000"
 - "8000:8000"
 - "49100:22"
 - "127.0.0.1:8001:8001"

expose

Expose ports without publishing them to the host machine - they'll only be accessible to linked services. Only the internal port can be specified.

expose:
 - "3000"
 - "8000"

volumes

Mount paths as volumes, optionally specifying a path on the host machine (HOST:CONTAINER), or an access mode (HOST:CONTAINER:ro).

volumes:
 - /var/lib/mysql
 - cache/:/tmp/cache
 - ~/configs:/etc/configs/:ro

volumes_from

Mount all of the volumes from another service or container.

volumes_from:
 - service_name
 - container_name

environment

Add environment variables. You can use either an array or a dictionary.

Environment variables with only a key are resolved to their values on the machine Fig is running on, which can be helpful for secret or host-specific values.

environment:
  RACK_ENV: development
  SESSION_SECRET:

environment:
  - RACK_ENV=development
  - SESSION_SECRET

env_file

Add environment variables from a file. Can be a single value or a list.

Environment variables specified in environment override these values.

env_file:
  - .env

RACK_ENV: development

net

Networking mode. Use the same values as the docker client --net parameter.

net: "bridge"
net: "none"
net: "container:[name or id]"
net: "host"

dns

Custom DNS servers. Can be a single value or a list.

dns: 8.8.8.8
dns:
  - 8.8.8.8
  - 9.9.9.9

cap_add, cap_drop

Add or drop container capabilities. See man 7 capabilities for a full list.

cap_add:
  - ALL

cap_drop:
  - NET_ADMIN
  - SYS_ADMIN

dns_search

Custom DNS search domains. Can be a single value or a list.

dns_search: example.com
dns_search:
  - dc1.example.com
  - dc2.example.com

working_dir, entrypoint, user, hostname, domainname, mem_limit, privileged, restart

Each of these is a single value, analogous to its docker run counterpart.

working_dir: /code
entrypoint: /code/entrypoint.sh
user: postgresql

hostname: foo
domainname: foo.com

mem_limit: 1000000000
privileged: true

restart: always