Docker compose files

Environment variables

You can pass your own environment variables into your docker-compose file - for more details see Environment variables.

A standard docker0s app provides the following environment variables:

ENV_FILE

Path to the combined env file on the host

ASSETS_PATH

Path to the assets dir on the host

Assets are resources pushed to the server as part of the docker0s deployment - config files, scripts, media etc.

STORE_PATH

Path to the store dir on the host

The store is for files created by the containers - logs, databases, uploads etc.

Example usage in your docker-compose.yml:

services:
  postgres:
    image: postgres:latest
    restart: unless-stopped
    env_file: "${ENV_FILE}"
    volumes:
      - "${STORE_PATH}/db:/db"
      - "${ASSET_PATH}/scripts:/scripts"

Compose templates

If the docker-compose file ends in a .jinja2 extension, docker0s will treat it as a Jinja2 template. See the Jinja documentation for details of the template syntax.

The template will be able to reference other documents relative to it, regardless of whether it is a local file or a remote file on a git+... url.

The template is rendered with the context dict provided in compose_context, plus the following values:

host

A reference to the instantiated Host object.

Example usage in a template:

services:
  my_service:
    environment:
      domain: {{ host.name }}

env

A reference to the fully resolved environment variables that will be sent to the server. It is recommended to prefer environment variable substitution (eg ${env_var}) as it allows more flexibility when working on the server in the future, but the env context variable can be useful for conditional statements.

Example usage in a template:

services:
  my_service:
    environment:
      {% if env.domain %}
      domain: ${domain}
      {% endif %}

apps

A reference to the compose template contexts of other apps in the current manifest. Note that this includes env and the other context variables mentioned here.

App names are normalised, so can be specified as described in App naming, eg apps.MyApp, apps.my_app etc

Example usage in a template:

services:
  my_service:
    {% if smtp_relay in apps %}
    networks:
      - {{ apps.smtp_relay.network }}
    {% endif %}

docker0s, globals

Reserved for future use.

Take care not to use these variables in your own compose_context.