Create docker-compose files using command line

[honsiorovskyi]

Provide a simple interface to create new application specifications using command line.

[honsiorovskyi]

Proposal

Assume a command app create which takes N named arguments and produces a docker-compose.yml file using the corresponging directives in exactly the same order. This command should be as much compatible with the standard docker run as possible.

Example input:

app create --name proxy \
--service nginx \
    --image docker.io/nginx \
    --restart always \
    --volume "/data/proxy/config:/etc/nginx" \
    --volume "/data/proxy/logs:/var/log/nginx" \
    --env-file proxy.env \
    --env "constraint:node_type==frontend" \
--service redis \
    --image docker.io/redis \
    --restart always \
    --volume "/data/proxy/db:/var/lib/redis" \
    --env "constraint:node_type==db"

Example output:

# proxy.yml
nginx:
    image: docker.io/nginx
    restart: always
    volumes:
        - "/data/proxy/config:/etc/nginx"
        - "/data/proxy/logs:/var/log/nginx"
    env-file: proxy.env
    environment:
        - "constraint:node_type==frontend"

redis:
    image: docker.io/redis
    restart: always
    volumes:
        - "/data/proxy/db:/var/lib/redis"
    environment:
        - "constraint:node_type==db"

[honsiorovskyi]

Now we have an experimental implementation for this feature, although its syntax is compatible with docker-compose.yml directives, not Docker itself. This decision has its pros and cons, but basically it's simpler to implement, to test to understand, and it's also not so hard to rewrite Docker run command line to fit docker-compose, so it stays for now.

Currently supported almost all directives from docker-compose.yml except for that ones which belong to the version 2. Version 2 is not supported yet.