AWS Lambdaλ

Scott Leberknight12/01/2016

"AWS Lambda lets you run code without provisioning or managing servers…"

"there is no charge when your code is not running"

"run code for virtually any type of application or backend service…"

"…with zero administration"

Lambda is to running code…

…as S3 is to storing objects

S3 vs. Lambda

Provide objects to S3

S3 stores those objects transparently

S3

You don't know how or where objects are stored

No servers, drives, or disk space to manage

Charged only by amount stored

Provide function code to Lambda

Lambda executes code on demand

Lambda

You don't know how or where code is executed

No servers or VMs to manage

Charged only for execution time

What is a Lambda function?

Code

Dependencies (e.g. libraries, modules, binaries)

Configuration

Let's create a really simple function…

1. Create new function

2. Select blueprint (optional)

3. Configure trigger (optional)

4. Basic function info

5a. Enter function code

5b. Completed code

6a. Configure function

6b. More configuration

7. Review

8. Function created

9a. Configure test event

9b. Edit test event

10. Execution results

11. View CloudWatch Logs

12. Basic CloudWatch Metrics

13. Execute via AWS CLI

Supported Platforms

JavaScript (Node.js 4.3)

Python 2.7

Java8

What about costs?

First million requests per month are free

Plus duration of execution (GB-seconds) rounded up to nearest 100 milliseconds ($0.00001667 per GB-sec)

Charged 20¢ per million requests…

(information as of November 30, 2016)

First 400,000 GB-seconds per month are free

Pricing Example

https://aws.amazon.com/lambda/pricing/

One function, 128MB allocated, executed 30 million times, ran for 200ms each time…

Compute charges (GB-sec): $5.83

Request charges: $5.80

Total charges (month): $11.63

How can a λ be executed?

Manually in AWS Lambda console

Using AWS SDK to call Lambda API

HTTP requests via API Gateway

Events raised in AWS (e.g. an object created in S3, new data in Kinesis stream

Ways to invoke λ functions

RequestResponse (synchronous)

Event (asynchronous)

RequestResponse Invocation

When a λ function is:

Invoked via the AWS console

Invoked using the AWS CLI

Executed via the Amazon API Gateway

Event Invocations

When an AWS event triggers a λ function:

An object is created in S3

An Amazon SNS notification

A Kinesis or DynamoDB stream

Event Models: Push vs. Pull

Push - A service (e.g. S3) publishes an event to Lambda and invokes the function

Pull - Lambda polls streaming event source (Kinesis, DynamoDB) and invokes the function when new data arrives

Programming Model

Handler

Context Object

Logging

Exceptions

The following programming model examples are for Node.js…

The Python 2.7 and Java8 models are similar

Handler

exports.handler = (event, context, callback) => { // code...}

event contains input data

context contains metadata about the executing λ function

callback (Node.Js only) returns error or successful result to caller

Handler

exports.myHandler = (event, context, callback) => { console.log("Event: ", JSON.stringify(event, null, 2)); var result = { "product": event.x * event.y }; callback(null /* error*/, result);}

multiply.js

Handler name: multiply.myHandler

multiply.jsexports.myHandler

Context Object

contains metadata about a λ function

version

name

ARN (Amazon Resource Name)

memory (MB)

AWS request ID

log group

log stream

Cognito identity

client context (mobile)

remaining time (ms)

Logging

Logs are stored in AWS CloudWatch

Available via AWS console or CloudWatch API

console.info("Event: ", JSON.stringify(event, null, 2));

Exceptionsexports.myHandler = (event, context, callback) => { // code to compute the sum... if (sum > 42) { var error = new Error( "Sum cannot be more than the ultimate answer!"); callback(error); } else { callback(null, result); }}

CloudWatch

Monitoring λ functions

Logs and metrics in CloudWatch

Setup alarms

Create dashboards

What about permissions?

Functions execute with a role

Permissions: Role

Attach policies to roles

Permissions: Policy

Multiple PoliciesRead/write S3 objects Write to DynamoDB Write CloudWatch logs

Custom Policy

Deploying λ functions

Edit code in AWS console

Upload deployment package as a zip file

Upload deployment package from S3

AWS CloudFormation

Deployment Package

Contains function code and dependencies

myfunction.js node_modules/ node_modules/async node_modules/async/lib node_modules/async/lib/async.js ...

myfunction.zip

Manual Upload

(not repeatable)

Create via CLI

$ aws lambda create-function \ --function-name simple-deploy-test \ --description "deployment test function" --handler myfunction.myHandler \ --memory-size 128 \ --runtime nodejs4.3 \ --role arn:aws:iam::269911013159:role/deploy-test-role

(repeatable, easily to automate)

Versioning λ functions

Publishing a function creates a new version

$LATEST is the current, editable version

Previous versions are immutable

Publish via AWS console, CLI, or Lambda SDK

Editing $LATEST

Publish new version

New Version

Version History

Function Aliases

Use aliases to point to the proper version

Multiple aliases for separate deployment environments (e.g. dev, staging, production)

Refer to aliases, not specific versions

Multiple Aliases

When things go wrong…

Automatic retry for stream-based event sources (e.g. Kinesis, Dynamo)

Automatic retry for asynchronous events from non-stream-based sources (e.g. S3)

Manual retry for synchronous invocations

Container re-use

Functions run in an isolated container (sandbox)

Lambda may or may not re-use same container across different invocations

Be aware that files written to /tmp may still exist from previous invocations!

https://aws.amazon.com/blogs/compute/container-reuse-in-lambda/

Testing λ functions

lambda-local (Node.js, GitHub)

Mocking, e.g. context object & AWS SDKs

lambda-test-harness blueprint

aws-lambda-python-local (GitHub)

Here come the frameworks…

Chalice - Python micro-framework by AWS dev tools team

Apex - build, deploy, manage λ functions

Serverless - build web, mobile, IoT apps powered by Lambda & API Gateway

Resource Limits

Resources are not infinite - λ imposes limits

Examples:300 seconds (5 minutes) max execution time

Maximum 50MB deployment package

100 concurrent executions

See developer guide for details…http://docs.aws.amazon.com/lambda/latest/dg/limits.html

It's a wrap!

Lambda is to code as S3 is to storage

No servers, no VMs, no administration

Charged only when functions run

Synchronous or async

Many ways to invoke(events, API gateway, AWS SDK calls, AWS CLI, AWS console, etc.)

References

AWS Lambda in Action https://www.manning.com/books/aws-lambda-in-action

Serverless Architectures on AWS https://www.manning.com/books/serverless-architectures-on-aws

AWS Lambda https://aws.amazon.com/lambda/

Lambda Developer Guide http://docs.aws.amazon.com/lambda/latest/dg/

My Info

sleberknight atfortitudetec.com

www.fortitudetec.com

@sleberknight

scott.leberknight atgmail