A Go-based instant messaging system supporting private chats, group chats, offline messages, and online status management.

• User Authentication: JWT-based registration and login
• Real-time Messaging: WebSocket long connections
• Private & Group Chats: Comprehensive messaging capabilities
• Offline Message Handling: Message storage and retrieval
• Online Status: Redis-based presence management
• Kafka Integration: Asynchronous message processing
• Message Retry: Exponential backoff retry mechanism
• DLQ Support: Dead Letter Queue for failed messages

The system guarantees at-least-once delivery for messages processed through Kafka. Each message is persisted to the database before acknowledgment, ensuring no message loss.

Messages are idempotent through msg_id deduplication. If a message is processed multiple times (due to retry or re-consumption), it's only stored once in the database.

When message processing fails:

1. Retry Attempts: Up to 3 retries (configurable)
2. Backoff: Exponential backoff starting at 100ms, doubling each retry, capped at 10s
3. DLQ: After all retries exhausted, message is sent to Dead Letter Queue

• Go 1.23.6+
• Redis 7+
• Kafka 3.x
• MySQL 8+

1. Start dependencies using Docker:

docker run -d \
  --name redis \
  -p 6379:6379 \
  redis:7

docker run -d \
  --name mysql \
  -e MYSQL_ROOT_PASSWORD=root \
  -e MYSQL_DATABASE=im \
  -p 3306:3306 \
  mysql:8

docker run -d \
  --name zookeeper \
  -p 2181:2181 \
  confluentinc/cp-zookeeper:7.6.0

docker run -d \
  --name kafka \
  --link zookeeper:zookeeper \
  -e KAFKA_ZOOKEEPER_CONNECT=zookeeper:2181 \
  -e KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://localhost:9092 \
  -e KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR=1 \
  -p 9092:9092 \
  confluentinc/cp-kafka:7.6.0

2. Create database tables:

CREATE DATABASE IF NOT EXISTS im;

Edit config/local.yml to configure your environment:

app:
  host: "0.0.0.0"
  port: 8080
  name: "PingMe"
  env: "development"

database:
  host: "localhost"
  port: 3306
  username: "root"
  password: "root"
  name: "im"

redis:
  host: "localhost"
  port: 6379

kafka:
  brokers:
    - "localhost:9092"
  consumer_group: "pingme-consumer"
  topic_prefix: "pingme"
  retry_max_attempts: 3      # Max retry attempts
  retry_initial_backoff: 100 # Initial backoff (ms)
  retry_max_backoff: 10000  # Max backoff (ms)
  retry_multiplier: 2.0     # Backoff multiplier
  enable_dlq: true          # Enable Dead Letter Queue

# Download dependencies
go mod download
[![Go Version](https://img.shields.io/badge/Go-1.22+-00ADD8?logo=go)](https://go.dev/)

# Build
go build -o pingme-server ./cmd/server

# Run
./pingme-server

# Or with custom config
APP_CONF=/path/to/config.yml ./pingme-server

Override configuration using environment variables:

GET /health

Returns service health status.

GET /version

Returns service version information.

PingMe/
├── cmd/
│   └── server/           # Application entrypoint
├── internal/
│   ├── config/           # Configuration loading
│   ├── errorcode/        # Error code definitions
│   ├── handler/          # HTTP handlers
│   ├── logger/           # Logging utilities
│   └── middleware/       # HTTP middleware
├── pkg/
│   └── response/         # API response wrapper
├── config/               # Configuration files
├── go.mod
└── README.md

go test ./...

# Format code
go fmt ./...

# Run linter
go vet ./...

MIT License