Weather Lambda Function Demo

This repository contains a demo of a Lambda function for a weather app. The Lambda function is written in Golang and is designed to retrieve weather data from the third-party API, Tomorrow.io.

Prerequisites

Before running the Lambda function, make sure you have the following:

• An AWS account
• AWS CLI installed and configured
• Golang installed
• Terraform installed

Setup Terraform Backend

For best practices, we will store the Terraform state in an S3 bucket. Follow these steps to set up the backend:

1. Create an S3 Bucket and DynamoDB Table (only needed once):

   aws s3api create-bucket \
    --bucket <unique_bucket_name> \
    --region us-west-2 \
    --create-bucket-configuration LocationConstraint=us-west-2
   
   aws dynamodb create-table \
    --table-name terraform-lock \
    --attribute-definitions AttributeName=LockID,AttributeType=S \
    --key-schema AttributeName=LockID,KeyType=HASH \
    --billing-mode PAY_PER_REQUEST

2. Update the backend.tf file in the devops directory:

   terraform {
     backend "s3" {
       bucket         = "unique_bucket_name>"
       key            = "weather-app/terraform.tfstate"
       region         = "us-west-2"
       dynamodb_table = "terraform-lock"
     }
   }

Installation and Deployment

To install and deploy the Lambda function, follow these steps:

1. Clone the Repository:

   git clone https://github.com/SDBurt/go-weather-lambda.git
   cd go-weather-lambda

2. Navigate to the Project Directory:

   cd app

3. Build and Zip the Executable for your Lambda Function:

   make build

4. Navigate to the devops Directory:

   cd ../devops

5. Initialize Terraform:

   terraform init

6. Apply the Terraform Configuration:

   terraform apply -auto-approve

   This command will deploy all the necessary AWS resources including the IAM role, Lambda function, and DynamoDB table. Note the output values for function_url.

Usage

To use the Lambda function, follow these steps:

1. Make a Request to the Function URL:

   curl "<function-url>?city=<city-name>"

   Replace <function-url> with the URL provided in the Terraform output and <city-name> with the desired city name (e.g., NewYork).

Testing

To test the Lambda function, you can use the curl command as shown in the usage section. The function URL provided by Terraform will accept query parameters and return the weather data for the specified city.

Example:

curl "https://<your-lambda-url>?city=NewYork"

Cleanup

To remove the Lambda function and associated resources once you are done, follow these steps:

1. Destroy the Terraform-managed Infrastructure:

   terraform destroy -auto-approve

Project Structure

weather-app/
│
├── app/
│   ├── cmd/
│   │   └── main.go
│   ├── internal/
│   │   ├── handler/
│   │   │   └── handler.go
│   │   ├── weather/
│   │   │   └── weather.go
│   │   ├── cache/
│   │   │   └── cache.go
│   │   ├── db/
│   │   │   └── db.go
│   │   └── log/
│   │       └── log.go
│   ├── go.mod
│   ├── go.sum
│   ├── .env
│   ├── Makefile
│   └── lambda-handler.zip
│
├── devops/
│   ├── main.tf
│   ├── backend.tf
│   ├── variables.tf
│   └── outputs.tf
│
└── README.md

Contributing

Contributions are welcome! If you find any issues or have suggestions for improvements, please open an issue or submit a pull request.

License

This project is licensed under the MIT License.