How to connect from VS Code dev Container to Postgres in Docker (Windows 11)

I am trying to connect to a dockerized Postgres from Python. However, I have not managed to make it work the way I believe it should work. As I am just a beginner with Docker, I used first used the postgres-pgadmin yaml from the awesome-compose github, as follows:

version: '3.1'

services:
  postgres:  
   image: postgres:16.0
   container_name: postgresdb
   restart: always
   ports:
     - "5432:5432"
   environment:
     - PGDATA=/var/lib/postgresql/data/pgdata
     - POSTGRES_USER=postgres
     - POSTGRES_PASSWORD=postgres
   volumes:
     - d:/DB/dev:/var/lib/postgresql/data
     
  pgadmin:
    container_name: pgadmin
    image: dpage/pgadmin4:latest
    environment:
      - [email protected]
      - PGADMIN_DEFAULT_PASSWORD=pass
    ports:
      - "5050:80"
    restart: always

With this, I can access pgadmin using localhost:5050, and I see that postgres is up and running without errors.

Now, the absolutely only way to set up the postgres server in pgadmin that works for me is to use postgresdb as the host. Using 127.0.0.1, localhost, or the IP shown in inspect does not work. Also, no matter what I try, I can’t connect at all from python. Here is btw the python code:

import psycopg2

connection = psycopg2.connect(database="postgres", user='postgres', password='postgres', host='127.0.0.1', port=5432)

I also checked whether port 5432 is listening using netstat -ad and I can see both

0.0.0.0:5050
0.0.0.0:5432

These two entries don’t show up when I take the containers down, thus I strongly assume they come from the postgre and pgadmin. So, I don’t understand why I can’t connect to postgres through python.

Then I thought there would be some "oddity" (from a beginner perspective at least) with docker compose, so I spun up another container on the postgres image (using docker desktop directly, not docker compose). This initially also did not work, until I changed the host port to 5433 (i.e. used the 5433:5432 mapping). And now I was able to connect to the server via python, but had to use the "docker" IP, i.e. something like 172.17.0.3 AND it only worked with port 5432, despite the mapping to 5433.

I would have expected that I could use something like 127.0.0.1:5433 to connect, but that does not work.

As for the system, I’m on Windows 11 with WSL2, and docker desktop 4.23.0. I have the suspicion that there is something in Windows 11 that causes the issues, but I don’t know where to even start. Btw, did turn off virus and firewall, but to no avail.

Any help would be highly appreciated.