How to add ".env" in Jenkins via docker-compose

I have an Application that can be initiated via docker-compose. And that docker-compose file uses a ".env" file to get all the secret variables. Now I want to automate it with CI/CD using Jenkins. My question is how do I add ".env" file in that build without making the env file public?

Here is my docker-compose.yml

version: "3"
services:
  my-app:
    image: j0sal/nextjs-13-login
    ports:
      - "3001:3000"
    env_file:
      - .env

If possible I want to keep the .env file specific for that build. Is that possible?

You can add files to the Jenkins credentials store and access them in the pipelines using withCredentials step. So the pipeline will look something like this:

node('built-in') {
  withCredentials([file(credentialsId: 'secretFile', variable: 'SECRET_FILE')]) {
    sh '''
      docker compose up -d --env SECRET_FILE
      # do whatever you need to do with the containers
    '''
  }
}

And then the docker-compose.yml file will reference the variable instead of a hardcoded path:

version: "3"
services:
  my-app:
    image: j0sal/nextjs-13-login
    ports:
      - "3001:3000"
    env_file:
      - "${SECRET_FILE}"

Ideally you should be using secrets instead of env_file, but that's a different topic.