Serverless PHP Functions: AWS Lambda Advanced Level

Serverless PHP Functions: AWS Lambda — From Theory to Advanced Practice

Serverless architecture has long ceased to be exotic, and PHP, thanks to tools like Bref and Laravel Vapor, has confidently carved out its niche in the world of serverless computing. In this article, we will cover advanced techniques for working with AWS Lambda in PHP: how to overcome cold starts, configure operation inside a VPC, and efficiently process events from S3 and SQS. The material is intended for developers already familiar with the basics of deploying PHP applications on Lambda.

1. Cold Start Optimization: From 2 Seconds to 200 Milliseconds

The main enemy of serverless PHP applications is the cold start. Unlike Node.js or Python, PHP requires loading the interpreter and framework. Here's how to minimize delays.

1.1. Using Bref and Pre-compiled Layers

Bref is the de facto standard for running PHP on Lambda. It provides ready-made Layers with the PHP interpreter. To speed things up, use bref/extra-php-extensions and include only the necessary extensions.

Example basic serverless.yml configuration:

service: my-php-app\n\nprovider:\n  name: aws\n  runtime: provided.al2\n  region: eu-central-1\n\nplugins:\n  - ./vendor/bref/bref\n\nfunctions:\n  api:\n    handler: public/index.php\n    layers:\n      - ${bref:layer.php-81}\n    events:\n      - httpApi: '*'\n

1.2. Lazy Loading and Configuration Caching

Don't load the entire framework (Laravel, Symfony) on every request. Use Laravel Octane with Swoole or RoadRunner, but for Lambda, Bref Laravel Bridge is better suited, as it caches configs and routes.

Code for caching configuration in bootstrap.php:

// public/index.php (entry point for Lambda)\nrequire_once __DIR__ . '/../vendor/autoload.php';\n\n$app = require_once __DIR__ . '/../bootstrap/app.php';\n\n// Cache configuration on first run\nif (! file_exists(__DIR__ . '/../bootstrap/cache/config.php')) {\n    $app->make('config')->get('app');\n    // Save compiled config\n    file_put_contents(\n        __DIR__ . '/../bootstrap/cache/config.php',\n        '<?php return ' . var_export($app->make('config')->all(), true) . ';'\n    );\n} else {\n    $config = require __DIR__ . '/../bootstrap/cache/config.php';\n    $app->instance('config', $config);\n}\n\n$kernel = $app->make(Illuminate\\Contracts\\Http\\Kernel::class);\n$response = $kernel->handle(\n    $request = Illuminate\\Http\\Request::capture()\n);\n$response->send();\n$kernel->terminate($request, $response);\n

Tip: Set memorySize to 1024 MB and timeout to 30 seconds for a balance of speed and cost. More memory means a faster CPU.

2. Working with VPC: Connecting to RDS and ElastiCache

Lambda functions by default run outside your VPC. To access databases (RDS, Aurora) or cache (ElastiCache), you need to place the function inside a VPC. This adds complexity and increases cold start time by 5-10 seconds.

2.1. Configuring VPC in serverless.yml

functions:\n  processUser:\n    handler: src/handlers/userHandler.php\n    layers:\n      - ${bref:layer.php-81}\n    vpc:\n      securityGroupIds:\n        - sg-0123456789abcdef0\n      subnetIds:\n        - subnet-abc123\n        - subnet-def456\n    events:\n      - sqs:\n          arn: arn:aws:sqs:eu-central-1:123456789012:user-queue\n

2.2. Managing Connections via PDO

Use RDS Proxy connection pooling or ElastiCache for reusing connections within a single Lambda container.

Example of a database class with reus