Presentation "The Journey To Serverless At Home24" from Çağatay Gürtürk & Martin Lindenberg at the AWS E-Business Web Day for windows applications. All videos and presentations can be found here: http://amzn.to/2ds3aMX

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The Journey to Serverless
Çağatay 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 month
23 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 information
for each product
Planned as new microservice to break the
monolith
Less than 10000 requests per day
Response time of less than 100ms is
required

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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 AWS
Console)

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Serverless stack

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The Limitations
Number of supported languages are
limited. (We like GO more then Node!)
Container startup affects response times of
some 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 multiple
varieties
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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Case 1: Users add a voucher on mobile device
Nerdy LLDB output
Objective-C Code - Not for home use
Insanely easy implementation on mobile application
Only use AWS Cognito SDK

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Case 1: Users add a voucher on mobile device

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Case 2: Voucher data changes on Backend
We have an auxiliary DynamoDB table
to 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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AWS Lambda Problems and Solutions
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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AWS Lambda Problems and Solutions
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 autoscaling
mechanism.
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