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Dockerized Services

This section explains the Dockerized architecture of the project, covering the configuration of various services, their interactions, and decisions made along the way. Below, you'll find detailed insights into the tools, technologies, and configurations used to build a robust and scalable Dockerized environment.

Overview

What You'll Learn

By the end of this section, you will understand:

  • How the project's services are containerized using Docker.
  • The purpose and configuration of each service, including HAProxy, web servers, and Nagios.
  • Key challenges faced during the setup and how they were overcome.
  • Lessons learned and future improvements for scaling and optimization.

This project relies on Docker to create isolated and reproducible environments for running its services. The use of Docker Compose ensures seamless coordination and deployment.

Dockerized Setup

The following services are defined in the docker-compose.yml file:

HAProxy

  • Image: Built from the Dockerfile.dev in ./infrastructure/load_balancer.
  • Purpose: Acts as a load balancer to distribute traffic between the web servers.
  • Ports: Maps the port range 60000-60001 to the host for testing purposes.
  • Dependencies: Depends on web-a and web-b services to ensure they start first.

Web Servers

  • Web-A: A simple web server configured to respond with the message "Web Server: A".
    • Image: Built from Dockerfile.dev in ./infrastructure/web_server.
    • Environment: Injects the environment variable MESSAGE="Web Server: A".
    • Ports: Maps container port 5001 to host port 5001.
  • Web-B: Similar setup as Web-A, but configured to respond with "Web Server: B".
    • Environment: Sets MESSAGE="Web Server: B".
    • Ports: Maps container port 5002 to host port 5002.

Nagios

  • Image: Uses the official jasonrivers/nagios:latest image for monitoring.
  • Purpose: Provides a monitoring interface to observe the health and performance of services.
  • Configuration:
    • Mounts configuration files and scripts into the container:
      • /opt/nagios/etc: Maps the etc directory for Nagios configurations.
      • /opt/nagios/libexec: Maps the libexec directory for custom plugins.
    • Ports: Exposes Nagios on host port 8080.
    • Environment: Sets NAGIOS_TIMEZONE=UTC for consistent timestamps.
    • Restart Policy: Always restarts to ensure availability.

MkDocs

  • Image: Uses the official squidfunk/mkdocs-material image.
  • Purpose: Serves project documentation locally during development.
  • Configuration:
    • Maps the local mkdocs directory into the container for live edits.
    • Ports: Serves documentation on host port 8000.

Network

  • Name: expensify_network (custom bridge network).
  • Purpose: Ensures seamless communication between all containers.

Challenges Faced

Challenges Encountered
  • Dependency Management: Ensuring all services start in the correct order.
  • Port Conflicts: Avoiding collisions when mapping multiple container ports to the host.
  • Configuration Complexity: Managing multiple configuration files and ensuring they work seamlessly.

How I Solved Them

  • Dependency Management: Used the depends_on key in docker-compose.yml to specify service dependencies.
  • Port Conflicts: Assigned unique ports for each service and documented mappings clearly.
  • Configuration Complexity: Organized configuration files into well-defined directories for easier maintenance.

Lessons Learned

Key Takeaways
  • Docker Compose simplifies service orchestration but requires clear documentation for maintainability.
  • Using environment variables allows dynamic configurations and easier scaling.
  • Consistent naming conventions and well-structured directories significantly improve project clarity.

Future Enhancements

  • Scaling: Investigate Docker Swarm or Kubernetes for scaling the architecture to handle higher traffic.
  • Monitoring: Enhance monitoring with Prometheus and Grafana for detailed insights.
  • Security: Implement SSL/TLS termination at HAProxy for secure communication.