Connecting to Postgres Docker server - authentication failed - postgresql

Question

I have a PostgreSQL container set up that I can successfully connect to with Adminer but I'm getting an authentication error when trying to connect via something like DBeaver using the same credentials.
I have tried exposing port 5432 in the Dockerfile and can see on Windows for docker the port being correctly binded. I'm guessing that because it is an authentication error that the issue isn't that the server can not be seen but with the username or password?
Docker Compose file and Dockerfile look like this.
version: "3.7"
services:
db:
build: ./postgresql
image: postgresql
container_name: postgresql
restart: always
environment:
- POSTGRES_DB=trac
- POSTGRES_USER=user
- POSTGRES_PASSWORD=1234
ports:
- 5432:5432
adminer:
image: adminer
restart: always
ports:
- 8080:8080
nginx:
build: ./nginx
image: nginx_db
container_name: nginx_db
restart: always
ports:
- "8004:8004"
- "8005:8005"
Dockerfile: (Dockerfile will later be used to copy ssl certs and keys)
FROM postgres:9.6
EXPOSE 5432
Wondering if there is something else I should be doing to enable this to work via some other utility?
Any help would be great.
Thanks in advance.
Update:
Tried accessing the database through the IP of the postgresql container 172.28.0.3 but the connection times out which suggests that PostgreSQL is correctly listening on 0.0.0.0:5432 and for some reason the user and password are not usable outside of Docker even from the host machine using localhost.

Answer 1

Check your pg_hba.conf file in the Postgres data folder.
The default configuration is that you can only login from localhost (which I assume Adminer is doing) but not from external IPs.
In order to allow access from all external addresses vi password authentication, add the following line to your pg_hba.conf:
host all all * md5
Then you can connect to your postgres DB running in the docker container from outside, given you expose the Port (5432)

Answer 2

Use the command docker container inspect ${container_number}, this will tell you which IPaddress:ports are exposed external to the container.
The command 'docker container ls' will help identify the 'container number'

Answer 3

After updating my default db_name, I also had to update the docker-compose myself by explicitly exposing the ports as the OP did
db:
image: postgres:13-alpine
volumes:
- dev-db-data:/var/lib/postgresql/data
environment:
- POSTGRES_DB=devdb
- POSTGRES_USER=user
- POSTGRES_PASSWORD=1234
ports:
- 5432:5432
But the key here was restarting the server! DBeaver has connected to localhost:5432 :)