Docker Compose PostgreSQL server

In one container start the Docker server, the other one will be the client that is built based on the Dockerfile

version: '3.8'
services:
  client:
    build: .
    volumes:
    - .:/opt
    links:
    - postgres
    command: tail -f /dev/null
  postgres:
    image: postgres:latest
    environment:
      POSTGRES_USER: username
      POSTGRES_PASSWORD: password
      POSTGRES_DB: mydb
    volumes:
      - postgres-database-data:/var/lib/postgresql/data/

volumes:
  postgres-database-data:

The Dockerfile is built on top of a plain Ubuntu image

FROM ubuntu:23.04
RUN apt-get update && \
    apt-get install -y curl && \
    apt-get install -y inetutils-ping && \
    apt-get install -y postgresql-client && \
    echo DONE

Start the two containers:

docker-compose up -d

Connect to the client container:

$ docker exec -it postgresql_client_1 bash

# psql -h postgres --username username -d mydb

It will ask for a password:

Password for user username:

type in password

psql (14.5 (Ubuntu 14.5-0ubuntu0.22.04.1), server 15.1 (Debian 15.1-1.pgdg110+1))
WARNING: psql major version 14, server major version 15.
         Some psql features might not work.
Type "help" for help.

mydb=#

Alternativel, once inside the client docker container we can put the variable of the database in an environment variable and then we can run a command that will not wait for any input.

export PGPASSWORD=password
echo "SELECT CURRENT_TIME" | psql -h postgres -U username mydb