Question 80485 in Docker Question posted in
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Postgres docker does not create user defined in .env file

I am trying to run my app and a postgresql server via docker. I created a docker-compose.yml file that seems to be correct from what I have researched, but postgres is only creating the default postgres user.

I will try to include all relevant files and cli outputs.

docker-compose.yml

version: '3'
services:
  api:
    build: .
    ports:
      - "8000:8000"
    depends_on:
      - db
  db:
    image: postgres
    restart: always
    ports:
      - "5432:5432"
    env_file:
      - .env
    volumes:
      - db-data:/var/lib/postgresql/data
volumes:
  db-data:

.env

POSTGRES_USER="user123"
POSTGRES_PASSWORD="password456"
POSTGRES_DB="db"
POSTGRES_PORT="5432"
POSTGRES_HOST="localhost"
POSTGRES_URL="postgresql://${POSTGRES_USER}:${POSTGRES_PASSWORD}@${POSTGRES_HOST}:${POSTGRES_PORT}/${POSTGRES_DB}?schema=public"

PS > psql -h localhost -U user123

psql: error: FATAL:  role "user123" does not exist

PS > docker exec api_db_1 env

HOSTNAME=31876238fb66
POSTGRES_PORT=5432
POSTGRES_HOST=localhost
POSTGRES_URL=postgresql://user123:password456@localhost:5432/db?schema=public
POSTGRES_USER=user123
POSTGRES_PASSWORD=password456
POSTGRES_DB=db
GOSU_VERSION=1.16
LANG=en_US.utf8
PG_MAJOR=15
PG_VERSION=15.2-1.pgdg110+1
PGDATA=/var/lib/postgresql/data
HOME=/root

postgres=# SELECT usename from pg_user;

 usename
----------
 postgres
(1 row)
Tags:

2

Answers


  1. 0

    The user is only created when Postgres initializes an empty database. If you have an existing database in your volume, the POSTGRES_USER variable isn’t used.

    From the docs:

    Warning: the Docker specific variables will only have an effect if you
    start the container with a data directory that is empty; any
    pre-existing database will be left untouched on container startup.

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  2. 0

    It looks like the environment variables from the ‘.env’ file are not being used by the ‘db’ service. You can try to explicitly define the environment variables in the ‘docker-compose.yml’ file under the ‘db’ service:

    version: '3'
services:
  api:
    build: .
    ports:
      - "8000:8000"
    depends_on:
      - db
  db:
    image: postgres
    restart: always
    ports:
      - "5432:5432"
    environment:
      POSTGRES_USER: user123
      POSTGRES_PASSWORD: password456
      POSTGRES_DB: db
      POSTGRES_PORT: 5432
      POSTGRES_HOST: localhost
    volumes:
      - db-data:/var/lib/postgresql/data
volumes:
  db-data:

    By specifying the environment variables directly in the docker-compose.yml file, you ensure that the db service receives the correct values for the PostgreSQL configuration.

    After making these changes, run the following commands to recreate the containers:

    docker-compose down
docker-compose up -d

    Now, when you try to connect to the PostgreSQL server with the specified user, it should work as expected.

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