Download - AWS Lambda Function with Kotlin
Silicon Valley Code Camp
8 October 2017
AWS Lambda Function with Kotlin
Troy Miles• Troy Miles aka the RocknCoder
• Over 38 years of programming experience
• Speaker and author
• bit.ly/rc-jquerybook
• @therockncoder
• lynda.com Author!
Kotlin for Java Developers
Join me at KotlinConf 2+3 Nov 2017 in San Francisco
Agenda• Kotlin
• Microservice
• RESTful API
• HTTP Methods
• Amazon Lambda
• Amazon API Gateway
• Spring MVC
• Debugging
• Next Steps
A Microservice…• Is a service with one narrowly defined focused
• Is individually deployable
• Consists of one or more process
• Owns its data store
• Is replaceable
Amazon Web Services
• We’ve decided to move to AWS
• Two phases:
• Now - Lift and Shift - get it running on EC2
• Later - Microservices & Client-side - bust it apart
Kotlin
History
• Announced in 2011 by JetBrains
• Open sourced in 2012 under Apache 2
• Version 1.0 released February 2016
• May 2017 Google Kotlin an Android language
Features• Makes apps for Android, JVM, Browser, and Native
• 100% interoperable with Java
• Clean, succinct syntax
• Null-pointer exception safety
• Lambda functions and other function features
AWS Lambda
Treat AWS Like Money
• If your account is compromised, it can be very bad
• Criminals can easily charge thousands of $$$ of AWS services to you in minutes
• Never use your root account
• Always use 2FA
AWS Lambda• Runs code without provisioning servers
• Pay only for compute time used
• Scales automatically
• Uses CloudWatch for monitoring
• Execution environment is Amazon Linux
Lambda Pricing: Request
• You are charged for the number of requests +
• You are charged for the duration of the request
• The first 1 million requests are free
• $0.20 per 1 million requests after the first million
Lambda Pricing: Duration
• Duration is per second round up to the nearest 100ms
• You are charged $0.00001667 for every GB-second used
• The first 400,000 GB/seconds is free
• Faster and smaller lambdas are cheaper
Lambda Languages
C# No
Java* 8
Node.js 4.3
Node.js 6.10
Python 2.7
Python 3.6
Kotlin/Lambda Demo
AWS API Gateway
AWS API Gateway
• Fully managed service for programmatically creating APIs
• Tightly integrates with Lambda
• Combines with CloudFront for edge caching
• Think of it as a flexible front door for your API
Kotlin/API Gateway Demo
RESTful API• Makes use of HTTP methodologies defined by RFC
2616 protocol
• Preferred over SOAP since it uses less bandwidth
• Breaks down a transaction into a series of HTTP methods
• Stateless by design
GET MethodGET /resource
Request has body No
Successful response has body Yes
Safe Yes
Idempotent Yes
Cacheable Yes
HEAD MethodHEAD /resource (HEAD * )
Request has body No
Successful response has body No
Safe Yes
Idempotent Yes
Cacheable Yes
POST MethodPOST /resource
Request has body Yes
Successful response has body Yes
Safe No
Idempotent No
Cacheable No*
PUT MethodPUT /new-resource
Request has body Yes
Successful response has body No
Safe No
Idempotent Yes
Cacheable No
PATCH MethodPATCH /resource
Request has body Yes
Successful response has body No
Safe No
Idempotent No
Cacheable No
DELETE MethodDELETE /resource
Request has body No
Successful response has body No
Safe No
Idempotent Yes
Cacheable No
OPTIONS MethodOPTIONS /resource
Request has body No
Successful response has body Yes
Safe Yes
Idempotent No
Cacheable No
Spring
Spring Framework
• An application framework and IOC container for Java*
• Created by Rod Johnson in 2002
• Released under Apache 2.0 in June 2003
Spring MVC
• Model-View-Controller Web App Framework
• Implements the strategy pattern
• Easier testing than most web frameworks
HTTP Method Shortcuts
Get @GetMapping
Post @PostMapping
Put @PutMapping
Delete @DeleteMapping
Patch @PatchMapping
Head and Options
• @GetMapping and @RequestMapping(method=HttpMethod.GET) support Head transparently
• Options is handled automatically
Debugging
• System.out() or System.err() goes to log
• View the logs via CloudWatch
• This is no way to debug code
Local Debugging
• Luckily we still run our app locally
• Using a modern IDE, we can set breakpoints
It Ain’t Paradise
• Cold start time can be long
• Not a lot of documentation
• Tooling is rough
Next Steps
• Goal is to get compiled size down
• And the execution speed up
• Planning to try RatPack
• Also KotlinNative -
Links• https://github.com/awslabs/lambda-kotlin-groovy-
example
• https://www.infoq.com/articles/Ratpack-and-Spring-Boot
• https://aws.amazon.com/blogs/compute/kotlin-and-groovy-jvm-languages-with-aws-lambda/
• https://github.com/awslabs/aws-serverless-java-container
• https://kotlinlang.org/docs/tutorials/spring-boot-restful.html
