Using Docker-compose, how to access the container database via the same port in container and in host

Question

I'm running a docker-compose container for postgresql. The postgresql database in the container is running on the standard port 5432, and I am publishing that port out to port 5444 on the host (since the host's postgresql default port is in use).

I am using the same configuration on the host and in the container (a .env file that provides config settings for cli commands and the app as a whole). Unfortunately, whichever port I choose, one system will lose access. For example, I cannot run:

[k@host]$ pgsql -p 5444 # Connects

in the host and still have work inside the container:

[k@db-container]$ pgsql -p 5444 # Errors in container

The container's postgresql-server is running on 5432:

[k@db-container]$ pgsql -p 5432 # Connects successfully in container

and the ports are published via the docker-compose.yml via: - ports: - "5444:5432"

So currently I don't know how to configure the same port everywhere simply via the docker-compose.yml! expose command exposes the port but does not allow remapping, ports forwards host<-->container, but does not remap the internal port. I have thought of remapping the postgresql default port inside the postgresql container configuration, but fully reconfiguring postgresql seems non-trivial to do via docker-compose on every docker-compose up.

How can I remap the ports inside the container so that I can use port 5444 everywhere, in the host & container?

David Maze · Accepted Answer · 2019-01-09 23:59:04Z

2

The standard PostgreSQL client library supports several environment variables that tell it where the server is. In the same way that you can configure the host using $PGHOST, you can configure the port using $PGPORT.

In a Docker Compose context, it should be straightforward to set these:

version: '3'
services:
  postgres:
    image: postgres:11
    ports: ['5444:5432']
    volumes: ['./postgres:/var/lib/postgresql/data']
  myapp:
    build: .
    ports: ['8888:8888']
    env:
      PGHOST: postgres
      # default PGPORT=5432 will work fine

Similarly, if you're running the application in a development environment on the host, you can set

PGHOST=localhost PGPORT=5444 ./myapp

answered Jan 9, 2019 at 23:59

David Maze

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1 Comment

Kzqai Over a year ago

That works, I can modify the commands on my local development (by passing ENV vars), I'll do that, thanks.

Alex Yu · Accepted Answer · 2019-01-09 20:33:13Z

0

You can't use the same port on the host.

Nothing prevents you to run multiple instances if they has different IP-addresses.

psql -p 5444

Defaults to psql --host=127.0.0.1 -p 5444. If you want several instances - obviously you must make them different in some way.

answered Jan 9, 2019 at 20:33

Alex Yu

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