C# Cloud AWS - Day Three

Learning Objectives

• Understand how to deploy a backend using AWS Lambda.
• Learn how to expose Lambda functions using API Gateway.
• Automate AWS Lambda deployments using Terraform.
• (Optional) Split backend functionalities into separate Lambda functions, triggered via HTTP calls.

Instructions

1. Fork this repository.
2. Clone your fork to your machine.

Core Activity

Deploy Backend Using AWS Lambda and API Gateway

Steps

1. Create a Lambda Function:

   • Open the AWS Management Console and navigate to Lambda.
   • Click Create function.
   • Choose Author from scratch.
   • Name the function (e.g., MyBackendFunction).
   • Select the C# (.NET Core) runtime.
   • Click Create function.

2. Create an AWS Cli Access Key for your account

   • navigate to AWS IAM
   • under Users, find your username and click on it
   • visit the Security Credentials tab
   • Click on Create Access Key
   • Choose Command Line Interface as the Use Case
   • Save the Access Key safely on your machine
   • Click show and copy and save the Secret access key as well

3. Open the AWSLambda-Day-3 Solution

   • Install the Extension called AWS Toolkit in Visual Studio.
   • Once installed, open up AWS Explorer in VS: Views > AWS Explorer
   • Add new Profile with your User Credentials
     • Profile Type is IAM User Role
     • Profile Name: choose your name or some identifier tied to you
     • Enter the Access key and Secret key obtained in step 2 above
     • Ensure you pick the default region for your AWS services

4. Publish Application to AWS Lambad

   • Right click on Project and choose Publish Lambda function to AWS
   • Make sure to select the created profile in step 3 and the correct region
   • Choose Redeploy to existing and find the lambda you created in step 1
   • Click Upload OR
   • You can publish to folder and zip and upload manually

5. Configure function URL

   • Navigate into the function and go to confguration TAB
   • Click on Function URL and Enable and Choose NONE option for Auth Type
   • Save

Use Terraform to Automate Lambda Deployment

Prerequisites:

-[] Ensure that Terraform CLI is installed and AWS CLI is configured.

• Terraform
  • Add the Terraform.exe to your C:\Program Files\Git\usr\bin (If you have git Bash install.)
  • Otherwise and directory of your choice.
  • Add the Directory to your Environment Variable %PATH%
  • Steps on how to do it here Setup of Terraform in Environment Variables
• AWS Terraform

Steps

1. Write Terraform Configuration:

   • In your project folder, create a file named main.tf with the following content:

     provider "aws" {
        region = "eu-north-1"
     }
   
     resource "aws_iam_role" "lambda_role" {
        name = "lambda_role"
        assume_role_policy = jsonencode({
           Version = "2012-10-17",
           Statement = [{
              Action = "sts:AssumeRole",
              Effect = "Allow",
              Principal = {
              Service = "lambda.amazonaws.com"
              }
           }]
        })
     }
   
     resource "aws_lambda_function" "backend" {
        filename         = "backend.zip"
        function_name    = "MyBackendFunction"
        role             = aws_iam_role.lambda_role.arn
        handler          = "Backend::Backend.Function::FunctionHandler"
        runtime          = "dotnet6"
        source_code_hash = filebase64sha256("backend.zip")
     }
   
     resource "aws_api_gateway_rest_api" "api" {
        name = "MyBackendAPI"
     }
   
     resource "aws_api_gateway_resource" "resource" {
        rest_api_id = aws_api_gateway_rest_api.api.id
        parent_id   = aws_api_gateway_rest_api.api.root_resource_id
        path_part   = "register"
     }
   
     resource "aws_api_gateway_method" "method" {
        rest_api_id   = aws_api_gateway_rest_api.api.id
        resource_id   = aws_api_gateway_resource.resource.id
        http_method   = "GET"
        authorization = "NONE"
     }
   
     resource "aws_api_gateway_integration" "integration" {
        rest_api_id = aws_api_gateway_rest_api.api.id
        resource_id = aws_api_gateway_resource.resource.id
        http_method = aws_api_gateway_method.method.http_method
        type        = "AWS_PROXY"
        integration_http_method = "POST"
        uri         = aws_lambda_function.backend.invoke_arn
     }

2. Package Your Lambda Code:

   • Publish your Lambda function using the following commands:

   dotnet publish -c Release -o out
   cd out
   zip -r backend.zip .
   

3. Run Terraform:

   • Initialize Terraform:

   terraform init

   • Apply the configuration:

   terraform apply

4. Verify Lambda and API Gateway Deployment:

   • Check the API Gateway endpoint URL in AWS and ensure it is connected to the Lambda function by visiting https://your-api-id.execute-api.region.amazonaws.com/register.

(Optional) Split Functionalities into Multiple Lambda Functions

Steps

1. Create Additional Lambda Functions:

   • Create separate Lambda functions to handle different tasks. For example, create one function for user registration and another for order processing.

2. Update API Gateway:

   • In API Gateway, add new routes like /register and /order, linking each route to its respective Lambda function.

3. Test the API:

   • Verify that different routes trigger different Lambda functions. For instance:
   • /register calls the user registration function.
   • /order calls the order processing function.