Code Disciples

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Wed 18 September 2019

Running PostgreSQL in a docker Container

Posted by Abhishek Pednekar in Docker   

Containers have revolutionized the way software is built and shipped. They also provide a means wherein software no longer needs to be mandatorily installed since it can be directly run in the container. In this post, you will run PostgreSQL (postgres) and pgAdmin 4 in separate docker containers on a Windows machine using docker toolbox. Once both docker containers are up, you will use pgAdmin to connect to the postgres database.

This post assumes that the reader has docker installed and running on a Windows machine. Installation instructions can be found in the official documentation.

PostgreSQL is a free and open-source relational database management system
pgAdmin 4 is an open-source database management tool for postgres

Creating the docker containers

To create the postgres and pgAdmin docker containers, we will use a docker-compose.yml file.

version: '3.2'
services:

  postgres:
    image: postgres:latest
    ports:
      - '5432:5432'
    container_name: postgres
    environment:
      POSTGRES_USER: 'postgres'
      POSTGRES_PASSWORD: 'postgres-pass'
      POSTGRES_DB: 'postgres'
    volumes:
      - type: bind
        source: .
        target: /var/lib/postgres/data

  pgAdmin4:
    image: dpage/pgAdmin4
    container_name: pgAdmin4
    depends_on:
      - postgres
    ports:
      - '8080:80'
    environment:
      pgAdmin_DEFAULT_EMAIL: 'admin@pgAdmin.com'
      pgAdmin_DEFAULT_PASSWORD: 'pgAdmin-pass'

Let's go over the attributes in the file.

version is the version of the Compose file format
services provides configuration for the containers that will be started
image is the application image installed from Docker Hub
ports are the exposed host and container ports
environment contains the environment variables for the services defined in the yaml file
volume signifies the location of the persistent data stored in the container

To create the containers, you will need to run the docker-compose -f docker-compose.yml up command. To verify if the docker containers are running, you can use the docker container ls command.


docker1

Running pgAdmin 4

The docker-compose.yml file specifies 8080 as the port to run pgAdmin. However, since docker is running on Windows, pgAdmin cannot be accessed using http://localhost:8080. Instead, you will need to use the ip address of the virtual machine that is running docker toolbox. To get the ip address, you can run the docker-machine ls command. The ip address, in this case, is 192.168.99.101. Therefore the url for pgAdmin will be http://192.168.99.101:8080.

To log in, you will use the default email and password specified in the yaml file.


pgAdmin1

Connecting to a postgres database

Once logged into pgAdmin, you will select the Add New Server option to connect to the postgres database.


postgres1


The database name, username and the password will be as specified in the yaml file. The hostname will once again be the ip address of the virtual machine.


postgres2


postgres3

Creating database objects with psql

To create database objects, we can either use pgAdmin or the psql command line. To run psql, you will first need to run a bash shell in the container, then connect to our database and finally run our SQL statements. As an example, here is how you can create a new table.


psql


postgres4


Here is a link to official postgres tutorial.


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