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Overview

Showdown Trivia includes a complete Docker Compose setup that runs:
  • Application: Go web server
  • MongoDB: Database for game data and user information
  • Prometheus: Metrics collection and monitoring
  • Grafana: Metrics visualization dashboard

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Quick Start

1

Prerequisites

Ensure you have installed:
  • Docker (version 20.10 or higher)
  • Docker Compose (version 2.0 or higher)
2

Build and run

From the project root directory:
docker compose up --build
This command will:
  • Build the application Docker image
  • Pull required images (MongoDB, Prometheus, Grafana)
  • Start all services
  • Create necessary networks and volumes
3

Access the application

Once all services are running, access:

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Service Configuration

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Application Service

The main application is built using a multi-stage Dockerfile for optimized image size. Image: Built from Dockerfile
Port: 8080
Container Name: app Environment Variables: 
PORT=8080
DB_URL=mongodb://admin:admin11@mongo/trivia?authSource=admin
LOG_LEVEL=info
ENV=dev
The application depends on MongoDB and will wait for it to be ready before starting.

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MongoDB Service

Image: mongo:7.0.5
Port: 27017
Database: trivia Default Credentials:
  • Username: admin
  • Password: admin11
These are development credentials. Change them for production deployments by modifying the environment variables in compose.yaml.
Environment Variables: 
MONGO_INITDB_DATABASE=trivia
MONGO_INITDB_ROOT_USERNAME=admin
MONGO_INITDB_ROOT_PASSWORD=admin11

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Prometheus Service

Image: prom/prometheus:v2.40.4
Port: 9090 Configuration:
Prometheus is configured via /etc/prometheus/prometheus.yml, mounted from: 
./deployments/prometheus/prometheus.yml
This service scrapes metrics from the application for monitoring performance and game statistics.

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Grafana Service

Image: grafana/grafana:9.3.0
Port: 3000 Default Credentials:
  • Username: admin
  • Password: devops123
Volumes:
  • Configuration: ./deployments/grafana/datasources.yaml → /etc/grafana/provisioning/datasources/datasources.yaml
  • Data persistence: Named volume grafana
Grafana is pre-configured with Prometheus as a data source through the provisioned datasources configuration.

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Docker Compose File Structure

version: '3.8'
services:
  app:
    build: 
      context: ./.
      dockerfile: Dockerfile
    container_name: app
    depends_on:
      - mongo
    ports:
      - 8080:8080
    environment:
      - PORT=8080
      - DB_URL=mongodb://admin:admin11@mongo/trivia?authSource=admin
      - LOG_LEVEL=info
      - ENV=dev  
  mongo:
    image: 'mongo:7.0.5'
    ports:
      - 27017:27017
    environment:
      - MONGO_INITDB_DATABASE=trivia
      - MONGO_INITDB_ROOT_USERNAME=admin
      - MONGO_INITDB_ROOT_PASSWORD=admin11
  prometheus:
    image: prom/prometheus:v2.40.4
    ports:
      - 9090:9090
    volumes:
      - ./deployments/prometheus/prometheus.yml:/etc/prometheus/prometheus.yml
  grafana:
    image: grafana/grafana:9.3.0
    ports:
      - 3000:3000
    environment:
      - GF_SECURITY_ADMIN_USER=admin
      - GF_SECURITY_ADMIN_PASSWORD=devops123
    volumes:
      - ./deployments/grafana/datasources.yaml:/etc/grafana/provisioning/datasources/datasources.yaml
      - grafana:/var/lib/grafana
volumes:
  grafana:

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Dockerfile Overview

The application uses a multi-stage build for efficiency: Stage 1: Builder (golang:1.22.3-alpine3.18)
  • Downloads and verifies Go modules
  • Copies source code
  • Builds optimized binary with -ldflags="-s" (strips debug info)
Stage 2: Runtime (alpine:latest)
  • Minimal Alpine Linux base
  • Copies only the compiled binary
  • Exposes port 8080
  • Runs the application
The multi-stage build reduces the final image size significantly by excluding build tools and source code.

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Port Mappings

ServiceHost PortContainer PortPurpose
Application80808080Web application
MongoDB2701727017Database access
Prometheus90909090Metrics collection
Grafana30003000Dashboard UI

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Common Commands

docker compose up

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Data Persistence

The Grafana service uses a named volume (grafana) to persist:
  • Dashboard configurations
  • User preferences
  • Custom queries and annotations
MongoDB does not use a persistent volume in the default configuration. Data will be lost when the container is removed. Add a volume mapping for production use.

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Customization

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Change Application Port

Modify both the environment variable and port mapping: 
app:
  ports:
    - 3000:3000  # Change host port
  environment:
    - PORT=3000  # Change container port

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Use External MongoDB

Remove the mongo service and update the application’s DB_URL: 
app:
  environment:
    - DB_URL=mongodb://user:pass@external-host:27017/trivia?authSource=admin

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Change Log Level

Modify the LOG_LEVEL environment variable: 
environment:
  - LOG_LEVEL=debug  # or info, warn, error

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Monitoring Setup

After starting the services:
1

Access Grafana

Navigate to http://localhost:3000 and log in with:
  • Username: admin
  • Password: devops123
2

Verify Prometheus connection

Go to Configuration → Data Sources to confirm Prometheus is connected.
3

Create dashboards

Import or create dashboards to visualize application metrics, game statistics, and performance data.

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Troubleshooting

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Container fails to start

Check logs for the specific service: 
docker compose logs app

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Port already in use

Find and stop the conflicting process: 
lsof -ti:8080
kill -9 <PID>
Or change the port mapping in compose.yaml.

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MongoDB connection issues

Ensure the MongoDB container is healthy: 
docker compose ps
Verify the connection string matches the MongoDB service configuration.

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Production Considerations

The default configuration is for development. For production:
  • Change all default passwords
  • Add MongoDB persistence volume
  • Set ENV=prod for the application
  • Use LOG_LEVEL=info or warn
  • Configure proper network security
  • Set up SSL/TLS certificates
  • Use secrets management for credentials

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Next Steps

Local Setup

Set up the development environment without Docker

Configuration

Understand all configuration options and environment variables

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