the journey to serverless at home24 - reflections and insights

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The Journey to ServerlessÇağatay Gürtürk, Martin Lindenberg Software Engineering, Home24 AG

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Agenda

• About Home24

• Our Journey to AWS and Serverless Architectures

• Use cases of Serverless Applications

• Caveats and Solutions

• Question and Answer Session

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About home24

Europe's largest online only retailer for home furniture and living

Active in 7 countries, 5 different languages

100+ IT Employees

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Desktop website

4.2 million visitors per month23 millions page views per month

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• The Best Shopping Application in 2015 in Germany

• Selected as Featured app many times by App Store

Available in IOS and Android

80000+ Monthly Active Users

Mobile applications

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There is always an invisible part of the

Iceberg.

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Endless stuff to deal with by 100+ people and 10+ teams

Order Processing

Business Intelligence Tools

Supporting Services for Customer Facing

Apps

Financial Tools

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Home24 was launched with a modified

Magento software

MAGENTO

Monolithic PHP application on on-

premise infrastructure

OWN SOFTWARE

MICROSERVICE AND CLOUD

20152011 2013

Our technical journey

Switched to Microservice

architecture. Deprecated PHP: Every new project

in GO, JAVA and JS

Migrated to AWS

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Why Microservices?

• Teams can choose the right tool for every service

• Every team can hold the ownership of a service

• Every team can manage its own infrastructure

Thus,

• Increases autonomy for teams

• Distributes the infrastructural risks

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AWS Migration

Not only a provider change, but a mindset change

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Why AWS?

• Cost efficient

• Scalable

• Requires less operation effort

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What is serverless?

• Every service managed by AWS

• Pay as you go. No need for 24/7 running infrastructure

• Less operation effort

• Focus on Dev of business requirements instead of Ops

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On-Premise Serverless

Not only Lambda but…

And more services…

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Case Studies

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Serverless Case Studies

• Parcel Service (Simple) – Our first attempt. Basic REST API

• Margin DB (Medium) – Responding to cloud events with zero custom infrastructure

• Voucher Manager (Expert) – Fully serverless application using Cognito and Lambda

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Parcel Service

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Parcel Service

Stores delivery and packaging informationfor each product

Planned as new microservice to break themonolith

Less than 10000 requests per day

Response time of less than 100ms isrequired

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Previous stack for new microservices

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Serverless stack

API Gateway

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Deployment options

Serverless framework

Cloudformation

Manually (Using CLI scripts or AWSConsole)

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Serverless stack

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The Limitations

Number of supported languages arelimited. (We like GO more then Node!)

Container startup affects response times ofsome requests

SNI-Support required

API Gateway = public visible endpoint

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The Wins

Pay only for usage(+ 1 million requests free per month)

API‘s can be secured with api keys

More memory = More CPU = Lower latency

Response times down to 30ms are possible

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Price comparison

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Margin DB

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Margin DB

How much profit do we make per product?

More than 100.000 products with multiplevarieties

Daily recalculation

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Margin DB: event based workers

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Cost

Service Usage Cost ($)

S3 170 GB-Mo 5.01

Lambda 39 million sec. 690

SNS 110 Millions Req. 45

SQS 232 Millions Req. 116

SWF 38000 0.79

EC2 0 Hours 0!

Note: usage and cost information are approximate.

Previous EC2 cost was 800$ but it was difficult to scale

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Voucher Manager

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Lets users store their vouchers in their mobile devices and use them in their purchases with 1-click

Lets us send new vouchers or remove old ones over the air

Voucher Manager

Project started with AWS

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Voucher Manager

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Voucher Manager

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Cognito & Lambda

Stores user data in cloud with zero-backend

code

Support custom authentication as well as

social logins

Lambda hooks for more functionality

+

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Case 1: Users add a voucher on mobile device

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Nerdy LLDB output

Objective-C Code - Not for home use

Insanely easy implementation on mobile applicationOnly use AWS Cognito SDK

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Case 2: Voucher data changes on Backend

We have an auxiliary DynamoDB tableto keep this relationship

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Case 3: Add Voucher from other channels

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Cost

Service Usage Cost ($)

API Gateway 2.1 million req. 7.57

Lambda 385000 seconds 6.19

Cognito Sync 344.410 Sync operations 5.17

Amazon EC2 0 Hours 0!

Note: usage and cost information are approximate. Negligible costs of SNS and DynamoDB are not included.

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How we build?

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Tooling

• Native JAVA• Homemade deployment tools built by Gradle and Cloudformation

• Node.js• Serverless framework (Formerly JAWS)

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Problems and Solutions

Encountered problems, fixed and addressed ones

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AWS Lambda Problems and Solutions

Problem: Less control over server optimizations

Solution: It is natural. Still you can increase RAM and CPU usage

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Problem: Lack of standard deployment tools

Solution: AWS is not providing any automatic deployment tool but there are open source solutions or it is easy to develop your own

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Problem: Long cold start times. (Especially on JVM.)

Solution: Keep it warm. Invoke the function periodically using Route53 Health Check or Cloudwatch scheduled event

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API Gateway Problems and Solutions

Problem: Slower than classical EC2-ELB stack

Solution: According to our experience, for many applications API Gateway’s performance is satisfying. But if you are developing a really low-latency service, API Gateway might not be the right solution at the moment

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API Gateway Problems and Solutions

Problem: ACM support, GZIP compression and HTTP caching are missing

Solution: Put a Cloudfront distribution in front of API Gateway. With Cloudfront you can enable all these features

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DynamoDB Problems and Solutions

Problem: Auto-scaling is missing

Solution: Use Dynamic DynamoDB or implement a custom Lambda autoscalingmechanism.

Fingers crossed for Autoscaling support from AWS

Dynamic DynamoDB available at: https://github.com/sebdah/dynamic-dynamodb

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Future

Running the whole platform without EC2 Instances

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Selection criteria for Serverless

• Performance requirements

• Language/Framework requirements

• Scalability and High Availability Requirements

• Budget Constraints

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QUESTIONS & ANSWERS SESSION

the journey to serverless at home24 - reflections and insights

Technology