FcmGo

FcmGo is a lightweight Go application designed to send push notifications and messages using Firebase Cloud Messaging (FCM). It provides a simple REST API built with the Gin framework to send notifications to topics or specific device tokens.

Features

• Send notifications to FCM topics with customizable title, body, sound, and image.
• Send data messages to FCM topics.
• Send notifications to multiple device tokens.
• Send data messages to multiple device tokens.
• Simple status endpoint to check server health.
• Environment variable configuration using .env files.

Prerequisites

• Go 1.21 or higher
• Firebase project with a service account key (JSON file)
• Git (optional, for cloning the repository)

Installation

1. Clone the Repository (if applicable):

   git clone https://github.com/yourusername/fcmgo.git
   cd fcmgo

2. Install Dependencies: Run the following command to download all required Go modules:

   go mod tidy

3. Set Up Environment Variables: Create a .env file in the root directory and add your Firebase service account JSON:

   SERVICE_ACCOUNT_JSON={"type": "service_account", "project_id": "your-project-id", ...}
   

   Replace the value with your actual service account JSON string from the Firebase Console.

4. Build and Run: Compile and start the server:

   go build -o fcmgo
   ./fcmgo

   The server will run on http://localhost:8080.

Usage

FcmGo exposes a REST API to interact with Firebase Cloud Messaging. Below are the available endpoints:

Endpoints

1. Check Server Status

• Endpoint: GET /status
• Description: Returns the server status.
• Response:

  {
      "status": "OK"
  }

2. Send Notification to a Topic

• Endpoint: POST /send/topic/notification
• Description: Sends a notification to a specified FCM topic.
• Request Body:

  {
      "title": "Test Notification",
      "body": "This is a test message",
      "topic": "news",
      "sound": "default",
      "image": "https://example.com/image.png",
      "data": {
          "key1": "value1",
          "key2": "value2"
      }
  }

• Response:

  {
      "messageId": "projects/your-project-id/messages/123456789"
  }

3. Send Message to a Topic

• Endpoint: POST /send/topic/message
• Description: Sends a data-only message to a specified FCM topic.
• Request Body:

  {
      "topic": "news",
      "data": {
          "key1": "value1",
          "key2": "value2"
      }
  }

• Response:

  {
      "messageId": "projects/your-project-id/messages/123456789"
  }

4. Send Notification to Tokens

• Endpoint: POST /send/tokens/notification
• Description: Sends a notification to multiple device tokens.
• Request Body:

  {
      "title": "Test Notification",
      "body": "This is a test message",
      "tokens": ["token1", "token2"],
      "sound": "default",
      "image": "https://example.com/image.png",
      "data": {
          "key1": "value1",
          "key2": "value2"
      }
  }

• Response:

  {
      "successCount": 2,
      "failureCount": 0
  }

5. Send Message to Tokens

• Endpoint: POST /send/tokens/message
• Description: Sends a data-only message to multiple device tokens.
• Request Body:

  {
      "tokens": ["token1", "token2"],
      "data": {
          "key1": "value1",
          "key2": "value2"
      }
  }

• Response:

  {
      "successCount": 2,
      "failureCount": 0
  }

Project Structure

fcmgo/
├── config/          # Environment variable loading
├── firebase/        # Firebase initialization
├── handlers/        # API endpoint handlers
├── interfaces/      # Data types and structs
├── routes/          # API route definitions
├── utils/           # Logging utilities
├── main.go          # Application entry point
├── go.mod           # Go module dependencies
└── .env             # Environment variables (not tracked)

Dependencies

• Gin - HTTP web framework
• Firebase Go SDK - Firebase integration
• Godotenv - Environment variable loading

See go.mod for the full list of dependencies.

Error Handling

• If the .env file is missing or invalid, the application will log an error and exit.
• API endpoints return appropriate HTTP status codes (e.g., 400 for bad requests, 500 for server errors) with error messages in the response body.