Docker compose and postgres official image environment variables - postgresql

Question

Actually I'm using the following docker-compose.yml file
version: '3.3'
services:
postgres:
container_name: postgres
image: postgres:latest
restart: always
environment:
POSTGRES_USER: ${POSTGRES_USER}
POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
POSTGRES_DB: ${POSTGRES_DB}
PGDATA: /var/lib/postgresql/data/pgdata
ports:
- "5432:5432"
volumes:
- ./data/postgres/pgdata:/var/lib/postgresql/data/pgdata
I use also this .env file in the same directory of the docker-compose.yml file:
POSTGRES_USER=dbadm
POSTGRES_PASSWORD=dbpwd
POSTGRES_DB=db
Then I run a bash shell into container this way:
docker exec -ti postgres bash
And after this invoke the command:
psql -h postgres -U dbadm db
And I get the error:
psql: FATAL: password authentication failed for user "dbadm"
The strange fact is that if use the default image parameters:
psql -h postgres -U admin database
And insert the default password "password", it logs me in, and seems it's ignoring the environment variables.
What am I missing?
Additional logs from docker-compose up logs:
postgres | 2017-10-15 09:19:15.502 UTC [1] LOG: listening on IPv4 address "0.0.0.0", port 5432
postgres | 2017-10-15 09:19:15.502 UTC [1] LOG: listening on IPv6 address "::", port 5432
postgres | 2017-10-15 09:19:15.505 UTC [1] LOG: listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
postgres | 2017-10-15 09:19:15.524 UTC [22] LOG: database system was shut down at 2017-10-15 09:02:21 UTC
postgres | 2017-10-15 09:19:15.530 UTC [1] LOG: database system is ready to accept connections
Cannot see any "RUN" line about user, database and password setup.

Answer 1

according to https://hub.docker.com/_/postgres documentation.
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.

Answer 2

I have created a docker-compose yml and .env file with the details you've provided and everything works fine as you can see from the pictures below:
I think your problem lies when you are passing the -h parameter.
Inside the container will always be localhost however, outside you will have to pass:
hostname: postgres
inside your docker-compose file so it will have the postgres hostname