PostgreSQL Environment variables in Docker Compose 'No password has been set for the database'

Question

I am working on a project using Django and am trying to load an .env file to the PostgreSQL image in my docker-compose.yml script. However, for some reason, I can't load them.

After I run the 'docker-compose up' command, one of the warnings I get from db_1 is as follows:

.
.
.
db_1   | ****************************************************
db_1   | WARNING: No password has been set for the database.
db_1   |          This will allow anyone with access to the
db_1   |          Postgres port to access your database. In
db_1   |          Docker's default configuration, this is
db_1   |          effectively any other container on the same
db_1   |          system.
db_1   | 
db_1   |          Use "-e POSTGRES_PASSWORD=password" to set
db_1   |          it in "docker run".
db_1   | ****************************************************
.
.
.

To help reproduce the problem, here's my folder structure:

My project structure:

├── config/
│   ├── .env
├── src/
│   ├── manage.py
│   └── core
│   |   ├── __init__.py
│   |   ├── settings.py
│   |   ├── urls.py
│   |   ├── wsgi.py
├── docker-compose.yml
├── Dockerfile
└── requirements.txt

My Dockerfile:

FROM python:3.7.0
ENV PYTHONUNBUFFERED 1
RUN mkdir /code
WORKDIR /code
COPY requirements.txt /code/
RUN pip install -r requirements.txt
COPY . /code/

My docker-compose.yml:

version: '2'

services:
  db:
    image: postgres
    restart: always
    env_file:
      - ./config/.env
  web:
    build: .
    stdin_open: true
    tty: true
    command: python src/manage.py runserver 0.0.0.0:8000
    restart: always
    volumes:
      - .:/code
    ports:
      - "8000:8000"
    depends_on:
      - db

My .env file:

PGUSER=admin
PGDATABASE=db
PGPASSWORD=s3cr3t
PGHOST=h0st
PGPORT=5432

An interesting point is that I was able to load environment variables into settings.py using the dotenv library, the problem is actually setting the environment variables in the PostgreSQL image.

I am following this logic of environment variables specified by PostgreSQL itself: https://www.postgresql.org/docs/10/libpq-envars.html

Answer 1

1.POSTGRES_PASSWORD is environment variable use by docker engine to set up POSTGRES image in newly created container. It must be set in .env file or in docker-compose.yml file.

Other variable used by docker engine can be found here:

https://github.com/docker-library/docs/tree/master/postgres

2.PGPASSWORD is environment variable use by postgres engine. It is used with psql command.

export PGPASSWORD='password'
psql -h 'server name' -U 'user name' -d 'base name' \
     -c 'command'

Other variable used by postgres engine can be found here:

https://www.postgresql.org/docs/current/libpq-envars.html