How can I set runtime variable for docker compose environment variable

Question

I am creating a docker compose file which requires some environment variables. One of the env var is from aws ssm parameter. So I need to query the value from aws ssm when I build the docker image and put the value as one of the environment variable. How can I do that in docker compose file?

version: "2.3"
services:
  base:
    build:
      context: .
      args:
        - PYTHON_ENV=developmen
        - API_KEY= # find the value from ssm

Answer 1

There is no easy way to process ARGs in docker-compose file from a subshell. But you can do this with docker build command and docker-compose with key-value.

using the docker-compose command:

MY_KEY=$(aws  ssm get-parameter --name "test" --output text --query Parameter.Value) docker-compose build --no-cache

docker-compose

version: "2.3"
services:
  base:
    build:
      context: .
      args:
        - PYTHON_ENV=developmen
        - API_KEY=${MY_KEY}

Define ARGs in Dockerfile and run subshell during build time to get the SSM parameter value.

FROM alpine
ARG API_KEY=default
ENV API_KEY="$API_KEY"
RUN echo  "API_KEY is : $API_KEY"

During build get the value using aws-cli

docker build --no-cache --build-arg API_KEY="$(aws  ssm get-parameter --name "test" --output text --query Parameter.Value)" -t myimage .

With docker-compose you can also try with system environment variable.

version: "2.3"
services:
  base:
    build:
      context: .
      args:
        - PYTHON_ENV=developmen
        - API_KEY=${MY_KEY}

Export it as an ENV before docker-compose.

 export MY_KEY=$(aws  ssm get-parameter --name "test" --output text --query Parameter.Value) && docker-compose build --no-cache