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

Is your Dockerfile defined with `API_KEY`, You can set the varibale only when your Docker container contains the variable. Then FOllow my answer to define in docker-compose and .env file https://stackoverflow.com/questions/57861914/load-environment-variables-from-env-file-with-docker-and-php/57873096#57873096#answer-57873096 — Jinna Balu, Sep 11 '19 at 04:23

Adiii · Accepted Answer · 2019-09-11T06:04:24.047

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

This solutions is best than use awscli inside docker build to get the ssm parameter? Very nice explanation! Thanks! — Igor Eulálio, Jan 11 '22 at 02:08
Actually no, this is storing sensitive information in the dockerfile — Tony BenBrahim, Aug 11 '23 at 22:18

Rafaf Tahsin · Answer 2 · 2019-09-11T02:53:34.803

There's no way to run script/code inside docker-compose file. So, you have to run the dynamic api key generation script outside the docker-compose file.

Anyway, you can declare a variable like API_KEY_FROM_SSM in docker-compose file

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

and query the value from aws ssm and assign it to API_KEY_FROM_SSM when you build image.

API_KEY_FROM_SSM=$(your aws ssm script) docker-compose build

Hope, it helps.

How can I set runtime variable for docker compose environment variable

2 Answers2

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