Custom Runtimes

on AWS Lambda

My experience doing Serverless PHP

bene@theodo.co.uk

Ben Ellerby

@EllerbyBen

serverless-transformation

@EllerbyBen

Serverless

What is this Serverless thing?

Architectural movement
- Developers send application code which is run by the cloud provider in isolated containers abstracted from the developer.
- Use 3rd party services used to manage backend logic and state (e.g. Firebase, Cognito)
A framework with the same name

@EllerbyBen

Why Serverless?

💰 Cost reduction

👷‍♂️ #NoOps

💻 Developers focus on delivering business value

📈 More scalable

🌳 Greener

@EllerbyBen

Not just Lambda (FaaS)

Lambda

Dynamo

API Gateway

Compute

Storage

Data

API Proxy

Cognito

Auth

SQS

Queue

EventBridge

Event Bus

Power and Flexibility

@EllerbyBen

Runtimes

@EllerbyBen

Runtimes

@EllerbyBen

<?php
    echo "Not my choice!";
?/>

@EllerbyBen

RUNTIME
NOT FOUND

@EllerbyBen

Custom Runtimes

@EllerbyBen

Runtime Interface

HTTP API for custom runtimes to receive invocation events from Lambda and send response data back within the Lambda execution environment.

@EllerbyBen

Runtime Interface

curl
"http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/next"

Next Invocation
Invocation Response
Invocation Error
Initialization Error

@EllerbyBen

/runtime/invocation/next

Body: JSON Payload
Headers: Meta Data

Retrieves an invocation event.

https://docs.aws.amazon.com/lambda/latest/dg/runtimes-api.html

GET

@EllerbyBen

.../invocation/AwsRequestId

/response

Body: Response

Sends an invocation response to Lambda.

https://docs.aws.amazon.com/lambda/latest/dg/runtimes-api.html

POST

@EllerbyBen

.../invocation/AwsRequestId

/error

Body: Error Object

Sends an error response

https://docs.aws.amazon.com/lambda/latest/dg/runtimes-api.html

POST

@EllerbyBen

Custom Runtime

A runtime is a program that runs a Lambda function's handler method when the function is invoked.

https://docs.aws.amazon.com/lambda/latest/dg/runtimes-api.html

@EllerbyBen

Custom Runtime

bootstrap

Shell Script
Script in supported language
Binary file compiled on Amazon Linux

@EllerbyBen

bootstrap

Setup
Reading Handler Name (env)
Polling for invocations from API
Calling Handler with body
Posting response

@EllerbyBen

#!/bin/sh
cd $LAMBDA_TASK_ROOT
./node-v11.1.0-linux-x64/bin/node
runtime.js

https://docs.aws.amazon.com/lambda/latest/dg/runtimes-walkthrough.html

@EllerbyBen

#!/bin/sh

set -euo pipefail

# Initialization - load function handler
source $LAMBDA_TASK_ROOT/"$(echo $_HANDLER | cut -d. -f1).sh"

# Processing
while true
do
  HEADERS="$(mktemp)"
  # Get an event
  EVENT_DATA=$(curl -sS -LD "$HEADERS" -X GET "http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/next")
  REQUEST_ID=$(grep -Fi Lambda-Runtime-Aws-Request-Id "$HEADERS" | tr -d '[:space:]' | cut -d: -f2)

  # Execute the handler function from the script
  RESPONSE=$($(echo "$_HANDLER" | cut -d. -f2) "$EVENT_DATA")

  # Send the response
  curl -X POST "http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/$REQUEST_ID/response"  -d "$RESPONSE"
done

https://docs.aws.amazon.com/lambda/latest/dg/runtimes-walkthrough.html

@EllerbyBen

runtime-tutorial
├ bootstrap
└ function.sh

https://docs.aws.amazon.com/lambda/latest/dg/runtimes-walkthrough.html

@EllerbyBen

bootstrap

handler

@EllerbyBen

bootstrap

handler

34M

@EllerbyBen

Layers

@EllerbyBen

Layers

@EllerbyBen

A layer is a ZIP archive that contains libraries, a custom runtime, or other dependencies. With layers, you can use libraries in your function without needing to include them in your deployment package.

https://docs.aws.amazon.com/lambda/latest/dg/configuration-layers.html

@EllerbyBen

bootstrap

handler

@EllerbyBen

Reduce deployment package size.
Large dependency deployed less often.
Easier to manage when change rarely
Reduced code storage (75GB)

@EllerbyBen

https://aws.amazon.com/blogs/aws/new-for-aws-lambda-use-any-programming-language-and-share-common-components/

@EllerbyBen

layers:
  php7:
    path: layers/runtime
    
    
functions:
  setup:
    handler: hello
    layers:
      - { Ref: php7 }

@EllerbyBen

Find the AMI of the correct AWS Linux: amzn-ami-hvm-.*-gp2
Spin up a Large EC2 and ssh in.
Follow the download and build steps for your language of choice.
scp a zip down to local
touch and chmod +x 'bootstrap'
zip a runtime directory with the binary and bootstrap

@EllerbyBen

#!/opt/bin/php
<?php

// amzn-ami-hvm-2017.03.1.20170812-x86_64-gp2

function getNextRequest()
{
    $client = new \GuzzleHttp\Client();
    $response = $client->get('http://' . $_ENV['AWS_LAMBDA_RUNTIME_API'] . '/2018-06-01/runtime/invocation/next');

    return [
        'invocationId' => $response->getHeader('Lambda-Runtime-Aws-Request-Id')[0],
        'payload' => json_decode((string) $response->getBody(), true)
    ];
}

function sendResponse($invocationId, $response)
{
    $client = new \GuzzleHttp\Client();
    $client->post(
        'http://' . $_ENV['AWS_LAMBDA_RUNTIME_API'] . '/2018-06-01/runtime/invocation/' . $invocationId . '/response',
        ['body' => $response]
    );
}

// This is the request processing loop. Barring unrecoverable failure, this loop runs until the environment shuts down.
do {
    // Ask the runtime API for a request to handle.
    $request = getNextRequest();

    // Obtain the function name from the _HANDLER environment variable and ensure the function's code is available.
    $handlerFunction = array_slice(explode('.', $_ENV['_HANDLER']), -1)[0];
    require_once $_ENV['LAMBDA_TASK_ROOT'] . '/src/' . $handlerFunction . '.php';

    // Execute the desired function and obtain the response.
    $response = $handlerFunction($request['payload']);

    // Submit the response back to the runtime API.
    sendResponse($request['invocationId'], $response);
} while (true);

?>

@EllerbyBen

Local Dev

bootstrap

handler

local bootstrap

web

server

@EllerbyBen

Works on my cloud

@EllerbyBen

Would Bref not be Brief?

@EllerbyBen

Would Bref not be Brief

Documentation
PHP runtimes for AWS Lambda
Deployment tooling
PHP frameworks integration

https://bref.sh/docs/

@EllerbyBen

https://github.com/brefphp/bref/pull/113

@EllerbyBen

Any Runtime

But at what cost?

More complex local dev env
Managing lambda layer versions
Updating the underlying language
OS concerns (e.g. OpenSSL)

Conclusion

The custom runtime API let's you run any binary you want.

Lambda layers are a great way to share large dependencies, like your runtime and bootstrap.

Lambda layers reduce your deployment size.

@EllerbyBen

AWS Lambda is a very flexible tool, use it wisely.

serverless-transformation

@EllerbyBen

Custom Runtimes

on AWS Lambda

My experience doing Serverless PHP

Serverless

What is this Serverless thing?

Why Serverless?

Not just Lambda (FaaS)

Power and Flexibility

Runtimes

Runtimes

Runtime Interface

Runtime Interface

/runtime/invocation/next

Retrieves an invocation event.

.../invocation/AwsRequestId

/response

Sends an invocation response to Lambda. ​

.../invocation/AwsRequestId

/error

Sends an error response

Custom Runtime

Custom Runtime

Layers

Layers

Local Dev

Works on my cloud

Would Bref not be Brief?

Would Bref not be Brief

Documentation

PHP runtimes for AWS Lambda

Deployment tooling

PHP frameworks integration

Any Runtime

But at what cost?

Conclusion

Sends an invocation response to Lambda.