Can't connect to DB located in docker container

Question

I'm trying to create PostgreSQL DB inside docker container and connect to it from my local machine. Running docker-compose up -d with that inside docker-compose.yml:

version: '3.5'

services:
  db:
    image: postgres:12.2
    restart: always
    ports:
      - "5432:5432"
    environment:
      POSTGRES_DB: db
      POSTGRES_USER: root
      POSTGRES_PASSWORD: root

ended successfully. No crashes, errors of something. But, when I'm trying to connect to it with pgAdmin4 with these credentials:

• Host name/address: localhost
• Port: 5432
• Maintenance database: db
• Username: root
• Password: root

it says to me:

Unable to connect to server:

FATAL: password authentication failed for user "root"

---

My OS: Windows 10 build(1809)

PostgreSQL version (installed on local machine): 12

Docker version: 19.03.13, build 4484c46d9d

---

UPD 1:

After re-creating container with different ports (now it is 5433:5433), pgAdmin4 error changed:

Unable to connect to server:

server closed the connection unexpectedly This probably means the server terminated abnormally before or while processing the request.

Answer 1

Host name/address: localhost

Port: 5432

You are trying to connect to 5432 port on localhost. Are you sure your container is taking the host IP?

To make the container run with the host IP run the container with --network host option.

docker run --network host <rest of the command>

Note that if you use '--network host' option, then portmapping '-p' option is not needed. Read https://docs.docker.com/network/host/ for more information.

Answer 2

Have you checked you've cleaned away any old instances running locally and that you're not trying to access an old instance?

You can wipe out all local docker containers with: docker rm -f $(docker ps -aq)

Once you've got a clean environment you can try spin up the containers again locally and see if you can access the service. I copy/pasted what you have into a clean docker-compose.yaml and ran docker-compose up against the file - it worked and I logged in and was able to view the pg_user table.

If it still fails you can try to find the IP using: netstat -in | grep en0 which will show something like

en0 1500 192.168.1 **192.168.1.163** 15301832 - 9001208 - - -

this shows the external/accessible IP of the container. Try using the address shown (something similar to 192.168.1.163) instead of localhost