Postgres inside docker compose refusing connection from my server - postgresql

Question

I have a Golang server alongside Postgres instance running inside docker compose. For some reason the Postgres is refusing connection. From all of my previous searches, usually the problem is typo, not exposing the port, having SSL and so on, but I don't have anything like that going on and still having this issue
version: "3.2"
services:
ingress:
image: jwilder/nginx-proxy
ports:
- "3000:80"
volumes:
- /var/run/docker.sock:/tmp/docker.sock:ro
auth-service:
depends_on:
- rabbitmq
- auth-db
- ingress
build: ./auth
container_name: "auth-service"
ports:
- 3001:3000
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=postgres
- POSTGRES_HOST=auth-db
- POSTGRES_DB=auth-dev
- POSTGRES_PORT=5435
- PORT=3000
- RABBITMQ_USER=guest
- RABBITMQ_PASSWORD=guest
- RABBITMQ_HOST=rabbitmq
- RABBITMQ_PORT=5672
- VIRTUAL_HOST=api.twitchy.dev
- VIRTUAL_PATH=/v1/auth/
deploy:
restart_policy:
condition: on-failure
delay: 5s
max_attempts: 3
window: 120s
# networks:
# - rabbitmq_net
# - default
rabbitmq:
image: rabbitmq:3-management-alpine
container_name: "rabbitmq"
ports:
- 5672:5672
- 15672:15672
volumes:
- rabbitmq_data:/var/lib/rabbitmq/
- rabbitmq_log:/var/log/rabbitmq/
# networks:
# - rabbitmq_net
auth-db:
image: postgres:14.1-alpine
restart: always
container_name: "auth-db"
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=postgres
- POSTGRES_DB=auth-dev
ports:
- "5435:5432"
volumes:
- db:/var/lib/postgresql/data
chat-db:
image: postgres:14.1-alpine
restart: always
container_name: "chat-db"
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=postgres
- POSTGRES_DB=chat-dev
ports:
- "5434:5432"
volumes:
- db:/var/lib/postgresql/data
# networks:
# rabbitmq_net:
# driver: bridge
volumes:
db:
driver: local
rabbitmq_data:
rabbitmq_log:
This is the error I am getting
auth-service | Retrying connection to database...
auth-service | failed to connect to `host=auth-db user=postgres database=auth-dev`: dial error (dial tcp 172.23.0.3:5435: connect: connection refused)
And my Golang code used to connect to the DB (using pgx)
dbUrl := fmt.Sprintf("postgres://%s:%s#%s:%s/%s?sslmode=disable",
os.Getenv("POSTGRES_USER"),
os.Getenv("POSTGRES_PASSWORD"),
os.Getenv("POSTGRES_HOST"),
os.Getenv("POSTGRES_PORT"),
os.Getenv("POSTGRES_DB"))
This is why I am confused
The ports match up, I expose 5435 from postgres, and I connect to 5435
The host should be correct as I am referencing the auth-db service name and they are on the same default network so that should be fine
The password and username match up
The POSTGRES_DB also match up, the default database should be auth-dev
POSTGRES_DB
This optional environment variable can be used to define a different name for the default database that is created when the image is first started. If it is not specified, then the value of POSTGRES_USER will be used.
I have sslmode disable as well
Is there anything else that can cause the connection to be refused?
Tried changing db to template1 and postgres as they are created by default but both aren't working either
54511e50369c postgres:14.1-alpine "docker-entrypoint.s…" 16 minutes ago Up 16 seconds 0.0.0.0:5435->5432/tcp, :::5435->5432/tcp auth-db
docker exec -it 54511e50369c psql -U postgres
psql (14.1)
Type "help" for help.
postgres=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------+----------+----------+------------+------------+-----------------------
postgres | postgres | UTF8 | en_US.utf8 | en_US.utf8 |
template0 | postgres | UTF8 | en_US.utf8 | en_US.utf8 | =c/postgres +
| | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | en_US.utf8 | en_US.utf8 | =c/postgres +
| | | | | postgres=CTc/postgres
(3 rows)
The database is ready when I am trying to connect (I am retrying 20 times so, and restarting the service if it crashes, so it should be available)

Answer 1

When you map ports in docker-compose, say like "5435:5432", you are mapping port 5435 on the HOST machine to 5432 on the CONTAINER. However, your db url in the auth-service definition is using the name of the service, auth-db, so you are actually hitting the db container directly, not going through the host machine. Because the db container does not expose 5435, you are unable to connect using port 5435.
If you were to try to connect to the database from your host machine for example, you would probably be successful using port 5435 and localhost.