PowerShell Weather Function App

A PowerShell Azure Function App that provides weather data by calling the OpenWeatherMap API. This function can be run locally or deployed to Azure.

Features

• HTTP Trigger: Accepts GET and POST requests
• Weather Data: Retrieves current weather information for any city
• Error Handling: Comprehensive error handling and logging
• JSON Response: Returns structured JSON data
• Local Development: Can be run locally using Azure Functions Core Tools
• Cross-Platform: Works on macOS, Windows, and Linux
• Easy Setup: Includes startup scripts for quick deployment

Prerequisites

• PowerShell 7.4 or later
• Azure Functions Core Tools v4
• .NET Core SDK 6.0 or later
• OpenWeatherMap API key (free at openweathermap.org)

Quick Start (Cross-Platform)

Option 1: Use the Startup Scripts (Recommended)

For macOS/Linux:

git clone https://github.com/stormihein/powershell-weather-function.git
cd powershell-weather-function
chmod +x start-function.sh
./start-function.sh

For Windows:

git clone https://github.com/stormihein/powershell-weather-function.git
cd powershell-weather-function
.\start-function.ps1

The startup scripts will check for prerequisites and guide you through installation if needed.

Option 2: Manual Installation

1. Install PowerShell

macOS:

# Using Homebrew
brew install --cask powershell

# Or download from Microsoft
# https://github.com/PowerShell/PowerShell/releases

Windows:

# Using winget
winget install Microsoft.PowerShell

# Or download from Microsoft
# https://github.com/PowerShell/PowerShell/releases

2. Install .NET Core SDK

macOS:

# Using Homebrew
brew install --cask dotnet

# Or download from Microsoft
# https://dotnet.microsoft.com/download

Windows:

# Using winget
winget install Microsoft.DotNet.SDK.6

# Or download from Microsoft
# https://dotnet.microsoft.com/download

3. Install Azure Functions Core Tools

# Using npm (works on both macOS and Windows)
npm install -g azure-functions-core-tools@4 --unsafe-perm true

3. Get OpenWeatherMap API Key

1. Visit OpenWeatherMap
2. Sign up for a free account
3. Generate an API key
4. Update local.settings.json with your API key

Configuration

API Key Setup (Optional)

The function works with or without an API key thanks to built-in fallback mechanisms:

Option 1: With OpenWeatherMap API Key (Recommended) Create a local.settings.json file with your API key:

{
  "IsEncrypted": false,
  "Values": {
    "FUNCTIONS_WORKER_RUNTIME": "powershell",
    "FUNCTIONS_WORKER_RUNTIME_VERSION": "7.4",
    "AzureWebJobsStorage": "",
    "OPENWEATHER_API_KEY": "your_actual_api_key_here"
  }
}

Option 2: Without API Key (Works Out of the Box) If you don't have an API key, the function will automatically use the free wttr.in API. No configuration needed!

Running Locally

Quick Start with Scripts (Recommended)

macOS/Linux:

./start-function.sh

Windows:

.\start-function.ps1

Manual Start

# Navigate to the project directory
cd powershell-weather-function

# Set up .NET path (if needed)
export PATH="$HOME/.dotnet:$PATH"  # macOS/Linux
# or
$env:PATH = "$env:USERPROFILE\.dotnet;$env:PATH"  # Windows

# Start the function app
func start --port 7075

The function will be available at:

• http://localhost:7075/api/GetWeatherData

Testing the Function

Using curl

# Get weather for London
curl "http://localhost:7075/api/GetWeatherData?city=London"

# Get weather for New York
curl "http://localhost:7075/api/GetWeatherData?city=New%20York"

# Get weather for Tokyo
curl "http://localhost:7075/api/GetWeatherData?city=Tokyo"

Using PowerShell

# Get weather for London
Invoke-RestMethod -Uri "http://localhost:7075/api/GetWeatherData?city=London" -Method Get

# Get weather for New York
Invoke-RestMethod -Uri "http://localhost:7075/api/GetWeatherData?city=New%20York" -Method Get

Using the Test Script

# Run the included test script
.\test-function.ps1

# Or test specific cities
.\test-function.ps1 -City "Miami" -BaseUrl "http://localhost:7075"

Using a web browser

Navigate to: http://localhost:7075/api/GetWeatherData?city=London

API Usage

Request Parameters

Parameter	Type	Required	Description
city	string	No	City name (defaults to "London")

Response Format

{
  "Success": true,
  "Message": "Weather data retrieved successfully",
  "Data": {
    "City": "London",
    "Country": "GB",
    "Temperature": 15.2,
    "FeelsLike": 14.8,
    "Humidity": 78,
    "Pressure": 1013,
    "Description": "overcast clouds",
    "WindSpeed": 3.6,
    "WindDirection": 230,
    "Visibility": 10000,
    "Cloudiness": 90,
    "Timestamp": "2024-01-15 14:30:25"
  },
  "RequestedCity": "London"
}

Error Response

{
  "Success": false,
  "Message": "Failed to retrieve weather data",
  "Error": "Error message details",
  "RequestedCity": "InvalidCity"
}

Code Documentation

Function Structure

The main function (GetWeatherData/run.ps1) consists of:

1. Parameter Binding: Receives HTTP request data
2. Weather Data Function: Get-WeatherData function that:
   • Constructs the OpenWeatherMap API URL
   • Makes the HTTP request using Invoke-RestMethod
   • Extracts and formats weather data
   • Handles API errors
3. Main Logic:
   • Extracts city parameter from query string or request body
   • Gets API key from environment variables
   • Calls the weather data function
   • Formats and returns JSON response
4. Error Handling: Comprehensive try-catch blocks with proper error responses

Key Components

• HTTP Trigger: Configured in function.json to accept GET/POST requests
• Anonymous Access: Set to allow easy testing without authentication
• Environment Variables: API key stored securely in local.settings.json
• JSON Serialization: Uses PowerShell's ConvertTo-Json for response formatting

Deployment to Azure

Prerequisites

• Azure CLI installed
• Azure subscription
• Function App created in Azure

Deploy

# Login to Azure
az login

# Deploy the function app
func azure functionapp publish <your-function-app-name>

Troubleshooting

Common Issues

1. PowerShell not found: Ensure PowerShell 7.4+ is installed and in PATH
2. API key errors: Verify your OpenWeatherMap API key is correct
3. City not found: Ensure city names are spelled correctly and exist
4. Network issues: Check internet connectivity and firewall settings

Logs

Function execution logs are displayed in the terminal when running func start. Check these logs for detailed error information.

License

This project is open source and available under the MIT License.

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request

Support

For issues and questions:

• Check the troubleshooting section
• Review Azure Functions documentation
• Check OpenWeatherMap API documentation