Introducing the CDK construct library for the serverless LAMP stack

Update: The complete blog series and supporting GitHub repository is now available:

Part 1: Introducing the new Serverless LAMP stack
Part 2: Scaling relational databases
Part 3: Replacing the web server
Part 4: Building a serverless Laravel application
Part 5: The CDK construct library for the serverless LAMP stack
Part 6: From MVC to serverless microservices
Additional: Building PHP Lambda functions with Docker container images

In this post, you learn how the new CDK construct library for the serverless LAMP stack is helping developers build serverless PHP applications.

The AWS Cloud Development Kit (AWS CDK) is an open source software development framework for defining cloud application resources in code. It allows developers to define their infrastructure in familiar programming languages such as TypeScript, Python, C# or Java. Developers benefit from the features those languages provide such as Interfaces, Generics, Inheritance, and Method Access Modifiers. The AWS Construct Library provides a broad set of modules that expose APIs for defining AWS resources in CDK applications.

The “Serverless LAMP stack” blog series provides best practices, code examples and deep dives into many serverless concepts and demonstrates how these are applied to PHP applications. It also highlights valuable contributions from the community to help spark inspiration for PHP developers.

The CDK construct library for the serverless LAMP stack is an abstraction created by AWS Developer Advocate, Pahud Hsieh. It offers a single high-level component for defining all resources that make up the serverless LAMP stack.

CDK construct for Serverless LAMP stack

Amazon API Gateway HTTP API.
AWS Lambda with Bref-FPM runtime.
Amazon Aurora for MySQL database cluster with Amazon RDS Proxy enabled.

Why build PHP applications with AWS CDK constructs?

Building complex web applications from scratch is a time-consuming process. PHP frameworks such as Laravel and Symfony provide a structured and standardized way to build web applications. Using templates and generic components helps reduce overall development effort. Using a serverless approach helps to address some of the traditional LAMP stack challenges of scalability and infrastructure management. Defining these resources with the AWS CDK construct library allows developers to apply the same framework principles to infrastructure as code.

The AWS CDK enables fast and easy onboarding for new developers. In addition to improved readability through reduced codebase size, PHP developers can use their existing skills and tools to build cloud infrastructure. Familiar concepts such as objects, loops, and conditions help to reduce cognitive overhead. Defining the LAMP stack infrastructure for your PHP application within the same codebase reduces context switching and streamlines the provisioning process. Connect CDK constructs to deploy a serverless LAMP infrastructure quickly with minimal code.

Code is a liability and with the AWS CDK you are applying the serverless first mindset to infra code by allowing others to create abstractions they maintain so you don’t need to. I always love deleting code

Says Matt Coulter, creator of CDK patterns – An open source resource for CDK based architecture patterns.

Building a serverless Laravel application with the ServerlessLaravel construct

The cdk-serverless-lamp construct library is built with aws/jsii and published as npm and Python modules. The stack is deployed in either TypeScript or Python and includes the ServerlessLaravel construct. This makes it easier for PHP developers to deploy a serverless Laravel application.

First, follow the “Working with the AWS CDK with in TypeScript“ steps to prepare the AWS CDK environment for TypeScript.

Deploy the serverless LAMP stack with the following steps:

Confirm the CDK CLI instillation:
$ cdk –version
Create a new Laravel project with AWS CDK:
$ mkdir serverless-lamp && cd serverless-lamp
Create directories for AWS CDK and Laravel project:
$ mkdir cdk codebase

Create the new Laravel project with docker

$ docker run --rm -ti \
--volume $PWD:/app \
composer create-project --prefer-dist laravel/laravel ./codebase

The cdk-serverless-lamp construct library uses the bref-FPM custom runtime to run PHP code in a Lambda function. The bref runtime performs similar functionality to Apache or NGINX by forwarding HTTP requests through the FastCGI protocol. This process is explained in detail in “The Serverless LAMP stack part 3: Replacing the web server”. In addition to this, a bref package named larval-bridge automatically configures Laravel to work on Lambda. This saves the developer from having to manually implement some of the configurations detailed in “The serverless LAMP stack part 4: Building a serverless Laravel application”

Install bref/bref and bref/laravel-bridge packages in the vendor directories:

$ cd codebase
$ docker run --rm -ti \
--volume $PWD:/app \
composer require bref/bref bref/laravel-bridge

Initialize the AWS CDK project with typescript.
```
$ cd ../cdk
$ cdk init -l typescript
```
Install the cdk-severless-lamp npm module
$ npm i cdk-serverless-lamp

This creates the following directory structure:

.
├── cdk
└── codebase

The cdk directory contains the AWS CDK resource definitions. The codebase directory contains the Laravel project.

Building a Laravel Project with the AWS CDK

Replace the contents of ./lib/cdk-stack.ts with:

import * as cdk from '@aws-cdk/core';
import * as path from 'path';
import { ServerlessLaravel } from 'cdk-serverless-lamp';

export class CdkStack extends cdk.Stack {
  constructor(scope: cdk.Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    new ServerlessLaravel(this, 'ServerlessLaravel', {
      brefLayerVersion: 'arn:aws:lambda:us-east-1:209497400698:layer:php-74-fpm:12',
      laravelPath: path.join(__dirname, '../../codebase'),
    });
  }
}

The brefLayerVersion argument refers to the AWS Lambda layer version ARN of the Bref PHP runtime. Select the correct ARN and corresponding Region from the bref website. This example deploys the stack into the us-east-1 Region with the corresponding Lambda layer version ARN for the Region.

Deploy the stack:
cdk deploy

Once the deployment is complete, an Amazon API Gateway HTTP API endpoint is returned in the CDK output. This URL serves the Laravel application.

CDK construct output for Serverless LAMP stack

The application is running PHP on Lambda using bref’s FPM custom runtime. This entire stack is deployed by a single instantiation of the ServerlessLaravel construct class with required properties.

Adding an Amazon Aurora database

The ServerlessLaravel stack is extended with the DatabaseCluster construct class to provision an Amazon Aurora database. Pass a Amazon RDS Proxy instance for this cluster to the ServerlessLaravel construct:

Edit the ./lib/cdk-stack.ts :

 import * as cdk from '@aws-cdk/core';
 import { InstanceType, Vpc } from '@aws-cdk/aws-ec2';
 import * as path from 'path';
 import { ServerlessLaravel, DatabaseCluster } from 'cdk-serverless-lamp';

 export class CdkStack extends cdk.Stack {
  constructor(scope: cdk.Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);
 const vpc = new Vpc(this, 'Vpc',{ maxAzs: 3, natGateways: 1 } )
    // the DatabaseCluster sharing the same vpc with the ServerlessLaravel
    const db = new DatabaseCluster(this, 'DatabaseCluster', { vpc, instanceType: new InstanceType('t3.small'), rdsProxy: true, })
    // the ServerlessLaravel
    new ServerlessLaravel(this, 'ServerlessLaravel', {
      brefLayerVersion: 'arn:aws:lambda:us-east-1:209497400698:layer:php-74-fpm:12',
      laravelPath: path.join(__dirname, '../composer/laravel-bref'),
      vpc, 
      databaseConfig: { writerEndpoint: db.rdsProxy!.endpoint, },
    });
  }
 }

Run cdk diff to check the difference :
$ cdk diff

The output shows that a shared VPC is created for the ServerlessLaravel stack and the DatabaseCluster stack. An Amazon Aurora DB cluster with a single DB instance and a default secret from AWS Secrets Manager is also created. The cdk-serverless-lamp construct library configures Amazon RDS proxy automatically with the required AWS IAM policies and connection rules.

Deploy the stack.
$ cdk deploy

The ServerlessLaravel stack is running with DatabaseCluster in a single VPC. A single Lambda function is automatically configured with the RDS Proxy DB_WRITER and DB_READER stored as Lambda environment variables.

Database authentication

The Lambda function authenticates to RDS Proxy with the execution IAM role. RDS Proxy authenticates to the Aurora DB cluster using the credentials stored in the AWS Secrets Manager. This is a more secure alternative to embedding database credentials in the application code base. Read “Introducing the serverless LAMP stack – part 2 relational databases” for more information on connecting to an Aurora DB cluster with Lambda using RDS Proxy.

Clean up

To remove the stack, run:
$ cdk destroy

The video below demonstrates a deployment with the CDK construct for the serverless LAMP stack.

Conclusion

This post introduces the new CDK construct library for the serverless LAMP stack. It explains how to use it to deploy a serverless Laravel application. Combining this with other CDK constructs such as DatabaseCluster gives PHP developers the building blocks to create scalable, repeatable patterns at speed with minimal coding.

With the CDK construct library for the serverless LAMP stack, PHP development teams can focus on shipping code without changing the way they build.

Start building serverless applications with PHP.

AWS Compute Blog