Use variables within your Docker Compose YAML file, using simple shell script and YAML template

Replace-Docker-Compose-Variables.md

For a small number of variables ('tokens'), I use a simple shell script along with a templated version of my YAML file. Here's an actual example:

files:

docker-compose-template.yml
docker-compose.yml
compose_replace.sh

run:

sh compose_replace.sh

script:

#!/bin/sh

# variables
base_url_token="{{ base_url }}" # find all these...
base_url="api.foo.com" # replace with url of public rest api
host_ip_token="{{ host_ip }}" # find all these...
host_ip=$(docker-machine ip $(docker-machine active)) # replace with ip of host running NGINX

# output
echo ${base_url_token} = ${base_url}
echo ${host_ip_token} = ${host_ip}

# find and replace
sed -e "s/${base_url_token}/${base_url}/g" \
    -e "s/${host_ip_token}/${host_ip}/g" \
    < docker-compose-template.yml \
    > docker-compose.yml

this in docker-compose-template.yml:

  extra_hosts:
   - "{{ base_url }}:{{ host_ip }}"

becomes this in docker-compose.yml:

  extra_hosts:
   - "api.acme.com:192.168.99.100"