How to Set Up a PostgreSQL Replication Architecture Database in a Docker-Compose Environment

A replication architecture database is a valuable approach for separating read and write responsibilities into different database servers. This allows for efficient scaling of the database based on the type of operations or transactions that occur. In this guide, we will set up a replication architecture database in a Docker environment using Docker Compose, specifically for our development environment.

Technologies Used

• PostgreSQL
• Docker Compose

Getting Started

• Install Docker Desktop

Docker Compose Setup

Begin by creating a docker-compose.yaml file to define the services, configurations, and dependencies for the PostgreSQL replication setup.

version: "3"
services:
  postgresql-master:
    image: bitnami/postgresql
    restart: always
    ports:
      - '5432:5432'
    volumes:
      - postgresql_master_data:/bitnami/postgresql
      - ./db.sql:/docker-entrypoint-initdb.d/db.sql
    environment:
      - POSTGRESQL_PGAUDIT_LOG=READ,WRITE
      - POSTGRESQL_LOG_HOSTNAME=true
      - POSTGRESQL_REPLICATION_MODE=master
      - POSTGRESQL_REPLICATION_USER=repl_user
      - POSTGRESQL_REPLICATION_PASSWORD=repl_user
      - POSTGRESQL_USERNAME=postgres
      - POSTGRESQL_PASSWORD=postgres
      - POSTGRESQL_DATABASE=development_database
      - ALLOW_EMPTY_PASSWORD=yes

  postgresql-slave:
    image: bitnami/postgresql
    restart: always
    ports:
      - '5432'
    depends_on:
      - postgresql-master
    environment:
      - POSTGRESQL_PASSWORD=postgres
      - POSTGRESQL_MASTER_HOST=postgresql-master
      - POSTGRESQL_PGAUDIT_LOG=READ
      - POSTGRESQL_LOG_HOSTNAME=true
      - POSTGRESQL_REPLICATION_MODE=slave
      - POSTGRESQL_REPLICATION_USER=repl_user
      - POSTGRESQL_REPLICATION_PASSWORD=repl_user
      - POSTGRESQL_MASTER_PORT_NUMBER=5432
      - ALLOW_EMPTY_PASSWORD=yes

volumes:
  postgresql_master_data:
    driver: local

This docker-compose.yaml file defines two services: postgresql-master and postgresql-slave. The postgresql-master service acts as the master node, while the postgresql-slave service acts as the slave node.

Explanation of Key Configurations

• PostgreSQL Master Service:
  • POSTGRESQL_REPLICATION_MODE=master: Specifies that this PostgreSQL instance is the master.
  • POSTGRESQL_REPLICATION_USER and POSTGRESQL_REPLICATION_PASSWORD: Credentials for replication.
  • POSTGRESQL_DATABASE: Name of the development database.
  • POSTGRESQL_PGAUDIT_LOG=READ,WRITE: Enables audit logging for read and write operations.
• PostgreSQL Slave Service:
  • POSTGRESQL_REPLICATION_MODE=slave: Specifies that this PostgreSQL instance is the slave.
  • POSTGRESQL_MASTER_HOST: Points to the host of the master node.
  • POSTGRESQL_MASTER_PORT_NUMBER: Port number on which the master node is running.
  • POSTGRESQL_PGAUDIT_LOG=READ: Enables audit logging for read operations.

Running the Setup

To start the PostgreSQL replication setup, navigate to the directory containing the docker-compose.yaml file and run:

docker-compose up -d

This will launch the services in detached mode. You can then access the master and slave databases separately, and any changes made in the master will be replicated to the slave.

This Docker-Compose setup provides a convenient way to implement PostgreSQL database replication for your development environment. Adjust the configurations based on your specific requirements and scaling needs.

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