Run Postgres Container with Ansible

Question

I am working to run a Postgres Docker container with Ansible playbook, but I'm having problems with passing the POSTGRES_USER and the POSTGRES_PASSWORD as env.

This is my playbook:

- name: Run Postgresql container
  hosts: db_farm
  gather_facts: no
  tasks:
    - name: Start docker service
      service:
        name: docker
        state: started

    - name: install pip dependencies
      pip:
        name: docker

- name: Create Postgres Container
      docker_container:
        name: hitch_postgres
        image: postgres:12
        state: started
        recreate: yes
        ports:
          - "5432:5432"
        volumes:
          - /home/hitch_postgres_data:/var/lib/postgresql/data
        env:
          POSTGRES_USER: "myuser"
          POSTGRES_PASSWORD: "myuser"

But when trying to connect to the server by first going into the container with docker exec -it hitch_postgres bash and running either psql -U myuser or psql -U postgresit shows this errors:

psql: error: FATAL:  role "myuser" does not exist
psql: error: FATAL:  role "postgres" does not exist  

I know Ansible has a module called postgresql_userbut when using it like this:

     postgresql_user:
       name: myuser
       password: myuser

It throws this error:

So, how to pass the environmental variables from Ansible that by using the Docker CLI would be as simple as adding -e POSTGRES_USER=123 -e POSTGRES_PASSWORD=123?

Answer 1

POSTGRES_USER and POSTGRES_PASSWORD are only used to initialise a database. If you gave the container a persistent place to store the database (/home/hitch_postgres_data in the question) then after the first successful launch it will contain a database with the user and the password from the environment variables, which were present at that time. Consecutive launches with other environment variables will not trigger initialisation and thus, no user will be created and no password will be updated.

If you wish to learn more about the init process check out the readme and the entrypoint script.