Weather Validator Project

Overview

This project is a Weather Validator that uses AWS services (Lambda, RDS, S3, and API Gateway, VPC, NAT Gateway, Internet Gateway, etc). The architecture can be seen below:

The application has a frontend component, using HTML, CSS, and JavaScript. The backend is composed of Lambda functions written in Java. The database is an RDS PostgreSQL instance.

Prerequisites

For Local Development:

• Docker
• Java 21
• Maven (3.9.9)
• Node.js (v23.5.0)
• Terraform (v1.9.3) + terraform-local
• LocalStack (for local development)
• AWS CLI
• Open Weather API key (free tier) - to include in terraform/variables.tf and terraform-local/variables.tf

For Deployment to AWS:

• AWS CLI
• Terraform (v1.9.3)

Deploying to AWS

Before proceeding, make sure you have the AWS CLI configured with the necessary permissions (use aws configure). Additionally, your account will need a user with AdministratorAccess policy attached. In other words:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": "*",
            "Resource": "*"
        }
    ]
}

For a fast and easy deployment, you can use the following steps. The Lambda jar files are already included in the project.

cd terraform
terraform init
terraform plan
terraform apply --auto-approve

Once this is done, you will need to run the following command to create the database tables:

aws lambda invoke --function-name db-setup --region us-east-1 output.json 

See the CloudFront URL in the output of the Terraform run. You can access the application using this URL. That's it! You have successfully deployed the Weather Validator project to AWS.

If you need to make changes in the cloud

Backend:

• change java files in the backend directory
• run mvn clean install in the backend directory
• run aws lambda update-function-code --function-name history-lambda --zip-file fileb://history-lambda/target/history-lambda-1.0.0.jar - change according to the function you are updating

Frontend:

• change files in the frontend directory
• run aws s3 sync ./ s3://weather-validator-bucket in the frontend directory

Infrastructure:

• change .tf files in the terraform directory
• run terraform apply --auto-approve in the terraform directory

Running the application locally

Backend - Lambda functions (make changes as you see fit):

    cd backend
    mvn clean install

Frontend

Install http-server:

npm install --global http-server

or

brew install http-server

Then:

cd frontend
http-server

You can change the files as needed. The frontend will be available at http://localhost:8080.

Run LocalStack and Deploy Infrastructure Locally

After installing the LocalStack CLI (via pip or homebrew), run the following command:

    DEBUG=1 localstack start

Deploy Infrastructure Locally:

After installing terraform-local, run the following commands:

    cd terraform-local
    tflocal init
    tflocal apply --auto-approve

Once this is done, you will need to run the following command to create the database tables:

awslocal lambda invoke --function-name db-setup --region us-east-1 output.json 

or

 aws --endpoint=http://localhost.localstack.cloud:4566 lambda invoke --function-name db-setup --region us-east-1 output.json

Note! It could happen that the tflocal apply executes successfully, but the resources are not ready yet, hence the endpoints will not be available to pass to the Lambdas and environment variables. Check the terraform.tfstate file, particularly for the HOST and PORT environment variables in the aws_lambda_function resource. These are the endpoint and port for the RDS Proxy instance. In this case, please run the command again. You will see that a few resources have changed:

Apply complete! Resources: 0 added, 8 changed, 0 destroyed.

In the Check Weather tab, you can enter a city name and click the "Get Weather" button. The application will display the weather for the city you entered, along with the verdict: the weather must be over 20 degrees Celsius with no clouds. Otherwise, the application will display a message saying the weather is not nice.

The history tab will display the history of the cities you have checked the weather for. The full data from the Weather API can be copied to the clipboard by clicking the "Copy" button.

Cleaning Up

• Destroy the cloud resources:

    cd terraform
    terraform destroy

• Destroy local resources:

    cd terraform-local
    tflocal destroy

Or just shut down the LocalStack container:

    localstack stop