This document is part of the Bosch Rexroth ctrlX OS App Development Guideline, and describes specific topics for Apps which are based on the Docker container technology

Please refer to the App Development Guide for further information about general requirements and checks

The content of this document may be subject of change in future.

1. Artifacts / Files

In addition to a native Ubuntu Core App, a Docker App shall provide the files in this list

Files	Description	Value(s)	Optional / Mandatory
Docker-compose.yml	The docker-compose.yml file contains the configuration and options to run the services required by the snap	docker-compose.yml	Mandatory
Docker-compose.env	The docker-compose.env file contains the environment variable(s) set to run the snaps	docker-compose.env	Optional

2. Base Checks

2.1 snapcraft yaml / snap.yaml

In addition to the checks for snap.yaml which are described here, a Docker App has additional elements:

Item	Content	Optional / Mandatory
docker-compose	configuration file	Mandatory
docker-volumes	manage app data	Mandatory

The mandatory entries must be provided like the following:

parts:
  docker-compose:
    plugin: dump
    source: ./docker-compose
    organize:
      '*': docker-compose/${SNAPCRAFT_PROJECT_NAME}/
slots:
  docker-compose:
    interface: content
    content: docker-compose
    source:
      read:
        - $SNAP/docker-compose/${SNAPCRAFT_PROJECT_NAME}
  docker-volumes:
    interface: content
    content: docker-volumes
    source:
      write:
        - $SNAP_DATA/docker-volumes/${SNAPCRAFT_PROJECT_NAME}

2.2 docker-compose.yml

Item	Content	Optional / Mandatory
version	version of the docker-compose	Mandatory
services	information about the docker images, like image name, container name, used ports, required volumes etc.	Mandatory
volumes	mounted volumes	Optional
ports	described ports are not conflicting with standard/blocked ports. and app uses only described ports	Optional

Note: For example, here you can find information about syntax of a compose file: https://github.com/compose-spec/compose-spec/blob/master/spec.md

2.3 docker-compose.env

This file is optional and provides all environment variables which are used in the docker-compose.yml

Item	Content	Optional / Mandatory
variables	All variables in docker-compose.yml are provided here	Optional