Weather API Service

This project is a weather API service built using Golang. The service fetches weather data from a third-party API (e.g., Visual Crossing API) and implements caching using Redis with a 12-hour expiration. The API allows clients to retrieve current weather information for a specified city and improves performance by caching frequently requested data.

Table of Contents

• Features
• System Architecture
• Installation and Setup
• API Endpoints
• API Tests
• Usage
• System Diagrams
• Contributing
• License

Features

• Retrieves real-time weather data from a third-party API
• Implements Redis-based caching for performance optimization
• Custom date format handling for proper time unmarshalling
• Graceful error handling for external API failures
• Extensible caching layer for future optimizations

System Architecture

The system architecture is designed as follows:

1. WeatherService:

   • Responsible for fetching weather data from the third-party API.
   • Implements caching using Redis to reduce API calls.
   • Handles unmarshalling of JSON responses, including custom date formats.

2. Redis Cache:

   • Caches weather data for each city with a 12-hour expiration to optimize repeated requests.

3. Third-Party Weather API:

   • This service fetches weather data from an external API like Visual Crossing.

4. Error Handling:

   • If the data is unavailable or if the external API returns an error, the service will return an appropriate message.

Installation and Setup

Prerequisites

• Golang (v1.18 or later)
• Redis for caching
• Docker (optional but recommended for running Redis and tests)
• Visual Crossing API key (or any compatible weather API)

Step-by-Step Setup

1. Clone the Repository:

   git clone https://github.com/your-username/weather-api.git
   cd weather-api

2. Set Up Environment Variables: You need to set the following environment variables for the API key and Redis connection:

   export WEATHER_API_KEY="your-weather-api-key"
   export REDIS_URL="redis://localhost:6379"

3. Install Dependencies: If you use Go modules, ensure you install all the required dependencies:

   go mod tidy

4. Run the Service: To start the weather service, run the following command:

   go run main.go

5. Run Redis: If you're using Docker, run Redis with:

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

API Endpoints

GET /weather/{city}

Fetches the weather data for a specified city. If the weather data is cached, it will return the cached response, otherwise, it will fetch fresh data from the third-party API.

• URL: /weather/{city}

• Method: GET

• URL Params:

  • city=[string] - Name of the city

• Success Response:

  • Code: 200 OK
  • Content: JSON containing weather data.

  Example Response:

  {
    "queryCost": 1,
    "latitude": 37.7749,
    "longitude": -122.4194,
    "resolvedAddress": "San Francisco, CA",
    "days": [
      {
        "datetime": "2024-10-20",
        "tempmax": 21.2,
        "tempmin": 13.5,
        "temp": 17.8,
        "humidity": 68.0,
        "precipprob": 5.0
      }
    ]
  }

• Error Response:

  • Code: 400 Bad Request

  • Message: City is required

  • Code: 500 Internal Server Error

  • Message: Failed to fetch weather data

API Tests

You can run API tests using curl or an API testing tool like Postman.

Example CURL Requests

1. Get Weather Data for a City:

   curl -X GET "http://localhost:8080/weather/London"

2. Handling Errors: If the city name is missing:

   curl -X GET "http://localhost:8080/weather/"

You can also use Postman to simulate the requests and validate responses.

Usage

Once the service is running, you can query the weather data for a specific city by sending an HTTP GET request to the /weather/{city} endpoint. For example:

curl http://localhost:8080/weather/London

The service will first check if the data is available in the Redis cache. If not, it will fetch the data from the third-party weather API and store it in Redis with a 12-hour expiration.

System Diagrams

Contributing

Contributions are welcome! Please feel free to submit a pull request or open an issue if you find any bugs or want to request new features.

License

This project is licensed under the MIT License - see the LICENSE file for details.