Cannot connect to postgres client within docker container from OUTSIDE container

Question

I am not sure as to why I cannot connect my postgres client in my docker container from OUTSIDE my docker container.

docker-compose setup

  db:
    container_name: postgres-container
    image: postgres:latest
    ports:
      - "5432:5432"
    environment: 
      - POSTGRES_USER=liondancer
      - POSTGRES_PASSWORD=postgres
    volumes: 
      - ../data/postgres:/var/lib/postgresql/data

With my container running via docker-compose

$ docker exec -it 451b psql -U liondancer                                                                                                                              
psql (13.1 (Debian 13.1-1.pgdg100+1))
Type "help" for help.

liondancer=# \l
                                         List of databases
        Name         |   Owner    | Encoding |  Collate   |   Ctype    |     Access privileges     
---------------------+------------+----------+------------+------------+---------------------------
 liondancer          | liondancer | UTF8     | en_US.utf8 | en_US.utf8 | 
 journey_development | liondancer | UTF8     | en_US.utf8 | en_US.utf8 | 
 journey_test        | liondancer | UTF8     | en_US.utf8 | en_US.utf8 | 
 postgres            | liondancer | UTF8     | en_US.utf8 | en_US.utf8 | 
 template0           | liondancer | UTF8     | en_US.utf8 | en_US.utf8 | =c/liondancer            +
                     |            |          |            |            | liondancer=CTc/liondancer
 template1           | liondancer | UTF8     | en_US.utf8 | en_US.utf8 | =c/liondancer            +
                     |            |          |            |            | liondancer=CTc/liondancer
(6 rows)

Here is the output of docker ps

$ docker ps                                                                                                                                                          
CONTAINER ID   IMAGE             COMMAND                  CREATED             STATUS          PORTS                    NAMES
451b08a85664   postgres:latest   "docker-entrypoint.s…"   About an hour ago   Up 19 minutes   0.0.0.0:5432->5432/tcp   postgres-container

However, I want my rails server and pgAdmin (currently NOT in container) to be able to communicate with the postgres docker container client. I thought if my rails server , pgAdmin , or psql client connected to 0.0.0.0:5432 , I should be able to connect to the docker container client.

My attempts to connect have been

$ psql -h 0.0.0.0 -p 5432 -U liondancer -d journey_development                                                                                                       
psql: error: FATAL:  database "journey_development" does not exist

$ psql postgresql://liondancer:postgres@localhost:5432/                                                                                                              
psql: error: FATAL:  database "liondancer" does not exist

$ psql postgresql://liondancer:postgres@localhost:5432/journey_development                                                                                             
psql: error: FATAL:  database "journey_development" does not exist

In rails database.yml

default: &default
  adapter: postgresql
  encoding: unicode
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  host: <%= ENV.fetch("POSTGRES_HOST") { "0.0.0.0" } %>
  port: <%= ENV.fetch("POSTGRES_PORT") { "5432" } %>
  username: <%= ENV.fetch("POSTGRES_USER") { "liondancer" } %>
  password: <%= ENV.fetch("POSTGRES_PASSWORD") { "postgres" } %>

development:
  <<: *default
  database: journey_development

test:
  <<: *default
  database: journey_test

Answer 1

Try adding this to the environment variables:

POSTGRES_DB=journey_development

To access from outside the container try this command:

psql journey_development -h localhost -U liondancer
# Password: postgres

You can checkout my blog post for a full setup with Node TS, Postgres and Docker for dev and prod builds. https://yzia2000.github.io/blog/2021/01/15/docker-postgres-node.html

Answer 2

You can have an init script for creating the database and mount that init script to the postgres container. Example -

db:
    image: postgres:12
    environment:
      POSTGRES_USER: liondancer
      POSTGRES_PASSWORD: postgres
    volumes:
      - ./init.sql:/docker-entrypoint-initdb.d/init.sql
      - postgres_data:/var/lib/postgresql/data

Create an init.sql file in the same directory as the docker-compose.yml file with the following contents -

CREATE DATABASE journey_development WITH OWNER=liondancer LC_COLLATE='en_US.utf8' LC_CTYPE='en_US.utf8' ENCODING='UTF8';

This init.sql script is executed whenever the container is created and a database will be created for you.

[Optional] You can also create an user inside the init.sql using -

create user liondancer;
alter user liondancer with encrypted password 'postgres';
create database journey_development;
grant all privileges on database journey_development to liondancer;