JFokus 2020 - How to migrate an application to serverless

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Migrating to Serverless
JFokus - Stockholm
4.2.2020
Marcia Villalba
@mavi888uy

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About me
AWS Developer Advocate
Coding for more than 15 years
Host of FooBar YouTube Channel
https://youtube.com/foobar_codes

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Definitions
The fun part 😆

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“... A monolithic application built as a single unit. …”
Martin Fowler
“... it is a natural way to approach system building…”
Main problems of monoliths
SCALE
COMPLEXITY

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”.. It is a small application that does one thing only and
does that one thing well. It is a small component that is
easily replaceble and independently deployed"
Susan Fowler
How big it is?
”… it can be rewriten in two weeks…”
Sam Newman

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Serverless
”Serverless is a
methodology for
planning, building and
deploying software in a
way that maximizes value
by minimizing
undifferentiated heavy
lifting…”
Jeremy Daly

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What it means that something is serverless?
No managing infrastructure High availability built in
Pay for what you useScales automagically

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Function as a Service (FaaS)
“AWS Lambda lets you run code without
provisioning or managing servers. ...
…Just upload your code and Lambda takes care
of everything required to run and scale your code
with high availability.
You can set up your code to automatically
trigger from other AWS services or call it directly
from any web or mobile app”
AWS – Lambda definition
AWS
Lambda

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How AWS Lambda works?
Event source Function Services
Node.js
Python
Java
C#
Go
Custom runtimes
Changes in
data state
Requests to
endpoints
Changes in
resource state
Amazon S3
DynamoDB
Amazon
SQS

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Managed Services – Backend as a Service
”Serverless was first used to
describe applications that
significantly or fully incorporate
third-party, cloud-hosted
applications and services, to
manage server-side logic and
state.”
Mike Roberts
Co-founder Symphonia
Amazon S3
Amazon SNS

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AWS most common buildings blocks for serverless applications
Compute Storage Databases
API management Messaging Analytics
Orchestration Monitoring User Management
API Gateway
AWS Lambda
AppSync
Step functions Event Brigde
Amazon S3
Amazon SNS Amazon SQS
CloudWatch
DynamoDB
Amazon Kinesis Amazon Athena
Amazon Cognito

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Managing unknowns

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Lack of technology knowledge

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Will this solve my problem?

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Foundational work

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Conway Law
”Any organization that designs a system will inevitably
produce a design whose structure is a copy of the
organization communication structure…”
Melvin Conway
Reverse Conway’s maneuver
Structure your organization to match the software you
would like to build
Small, agile teams – Two pizza teams

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Pick your tools
- Programming languages
- Deployment frameworks
- Developer tools

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Infrastructure as code
1. Minimize risk and bugs
2. Make infrastructure changes
repeatable and predictable
3. Release infrastructure changes using
the same tools as code changes
AWS Cloud
Development Kit
AWS
CloudFormation

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SAM template
AWSTemplateFormatVersion: '2010-09-09’
Transform: AWS::Serverless-2016-10-31
Resources:
GetFunction:
Type: AWS::Serverless::Function
Properties:
Handler: index.get
Runtime: nodejs8.10
CodeUri: src/
Policies:
- DynamoDBReadPolicy:
TableName: !Ref MyTable
Events:
GetResource:
Type: Api
Properties:
Path: /resource/{resourceId}
Method: get
MyTable:
Type: AWS::Serverless::SimpleTable
Just 20 lines to create:
• Lambda function
• IAM role
• API Gateway
• DynamoDB table

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CI/CD
AWS CodeBuildAWS CodeCommit AWS CodeDeployAWS CodePipeline

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Monitoring and observability
Amazon
CloudWatch AWS X-Ray AWS CloudTrail
Amazon CloudFront AWS Lambda Amazon DynamoDB Amazon API Gateway Elastic Load Balancing
Amazon Simple Storage
Service
Send metrics and logs to different services

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Migration strategies
The real fun part 😅

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The big rewrite
Please don’t do it

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The monolithic function
Good option if you want to migrate from an on-prem to the cloud
Combined with the next pattern it can be the first step
Some tools to help you out:
• For NodeJS:
- Serverless express (https://serverless.com/plugins/serverless-express/)
- Serverless HTTP (https://github.com/dougmoscrop/serverless-http)
• For Java
- Serverless Java Container (https://github.com/awslabs/aws-serverless-java-
container)

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Strangler pattern
Monolith
Users
DB
Monolith
Service1
LB
Users
DBDB
Monolith
LB
Service1 Service n
Users
DB DB DB

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The strangler pattern

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Steps for doing the strangler pattern
Migrating to serverless in 5 steps

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Big mess of Customer, orders and inventory business logic
OrderId Order info
CustomerId Customer
info…
CustomerId OrderId OrderId ItemId
ItemId Item info
DB manager
Authentication / User management

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Step 1 – Find the seams in the code
”… a seam is a portion of the code that can be treated
in isolation and worked on without impacting the rest
of the codebase…”
Michael Feathers

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Step 1 – Find the bounded context in the code
Examples of seams in Java
Package content
- Organize your code inside different packages if its not done already
Example of seams in Javascript
Modules
- Be careful when moving things around if you don’t have unit tests.

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ItemsCustomersOrders
OrderId Order info
CustomerId Customer
info…
CustomerId OrderId OrderId ItemId
ItemId Item info
DB manager
Authentication / User management

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Package1
Repository1
Package2
Repository2
PackageN
Repository
N
Monolithic application
DB
Step 2 – Organizing the data

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ItemsCustomers Orders
OrderId Order info
CustomerId Customer
info…
CustomerId OrderId
OrderId ItemId
ItemId Item info
DB order manager
DB customer
manager
DB items manager
Authentication / User management

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Step 3 – Move the code gracefully
1. Choose what to
migrate first
2. Rebuild it as a
serverless component
Tidy
Monolith
Users
DB
Tidy
Monolith
Service1
LB
Users
DBDB

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Where to start?
Strategy 1
Start with the least critical
part of your system
Strategy 2
Start with the part of the
system with the highest
return of invested time
🤔

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Tidy Monolith
LB
Users
Logical microservice
AWS Lambda AWS Lambda
AWS Lambda AWS Lambda
AWS Lambda
DB
DB

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Customer “microservice”
• Get customer orders details
• Get customer information
• Change customer information
• Add a new customer
• Delete a customer
• Get customer favourite items
• Manage customer ….
Orders
DB
Items

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Single responsibility principle
“A class should have only one reason to change”
Robert C. Martin – Uncle Bob
In the serverless worlds this means:
- Simpler functions – easier to know what they are doing
- Less code to test
- Single purpose functions are more secure
- Single purpose functions perform better

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Get order
detailsGet order
details
Orchestration
Get customer
orders
DB
Get customer orders
Get order
details
Order service
Generate
results

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AWS Step Functions
Visualize in the
console
Define in JSON Monitor
executions

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AWS Step Functions workflow
Get customer
orders
Lambda Function
Get order detail
Lambda function
Put result
together lambda
function
DB
Order service
Input Output
Get order detail
Lambda function
Order service
n times in parallel

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Choreography and event driven architectures
Add a customer
Save
customer info
DB
Generate
thumbnail
Update
customer info
with
thumbnail
DBStorage

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Decoupling the services and functions
- Independent releases
- Scalability
- Modular code
- Easy to maintain and to work on
Amazon Simple
Notification
Service
Amazon Simple
Queue Service
Amazon
EventBridge

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Save metadata
Lambda Function
DB
Amazon
EventBridge
AWS Cloud
Users
Save customer
info
Lambda Function
DB
AWS S3Create thumbnail
Lambda Function
AWS S3

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Replacing functionality with managed services
Amazon Cognito
Order service
Customer
service
Items service
Users

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Orders “microservice”
• Get different analytics of
orders placed
• ….
DB

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Serverless analytics pipeline
Amazon Cognito
Amazon S3 Users
Amazon
Kinesis Data
Firehose
Amazon
Athena
AWS Glue Amazon
QuickSight
S3
Bucket
AWS Cloud
Client

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Step 4 - Breaking the database
Migrate the data to the cloud
AWS Database migration service helps you with your
migration from on prem to the cloud.
AWS Database
Migration Service

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Managed SQL Databases
Amazon RDS
Amazon RDS Engines
• Easily scalable
• Automatic software patching
• Automated backups
• Database snapshots
• Multi-AZ deployments
• Automatic host replacement
• Encryption at rest and in transit

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Migrating to RDS – Orders tables
Amazon RDSRDS Proxy
Order Lambda
Functions

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What is Amazon DynamoDB?
Fully managed NoSQL Document or key-value
Fast and consistent
Scales to any workload
Access control

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DynamoDB Transactions API
TransactWriteItems
Synchronous update, put, delete, and check
• Atomic
• Automated Rollbacks
Up to 10 items within a transaction
Supports multiple tables
Complex conditional checks
DynamoDB

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Step 5 – Breaking the APIs
Tidy Monolith
Service1
Application Load
Balancer
Users
Elastic Load
Balancing

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Move traffic gradually to the new service
Tidy Monolith with
old service 1
Service1
Application Load
Balancer
Users
30% traffic
70% traffic
ALB Weighted Target Groups

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Case Study

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SCALING CHALLENGES
350
DONATIONS PER SECOND

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2016
Drupal 7 monolith
- Static content
- Pay-in fundraising
- Gift aid declaration
- Fundraiser gallery
- Contact us
Giving
Pages
Donate

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2017
Drupal 7 monolith
- Static content
- Contact us
Drupal 8
- Static content
Pay-in
fund-
raising
SMS
Gift aid
Fundraise
gallery
Giving
Pages
Donate

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2018
Drupal 8
- Static content
Pay-in fund-
raising
SMS
Gift aid
Giving
Pages
Donate
Contact
us
Red Nose
Comp
School
step calc

63. © 2019, Amazon Web Services, Inc. or its Affiliates.
2018
Drupal 8
- Static content
Pay-in fund-
raising
SMS
Gift aid
Contact
usGiving
Pages
Donate
Red Nose
Comp
School
step calc
Mailer Service
Postcode lookup

64. © 2019, Amazon Web Services, Inc. or its Affiliates.
2019
Drupal 8
- Static content
Pay-in fund-
raising
Contact
us
Payment Service layer
Image uploader service
Marketing preferences service
Mailer Service
Postcode lookup service
SMS Gift
Aid
Donate

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Donate
bit.ly/cr-donate-blueprint

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OLD VS NEW
March 2019 cost*
$5,393
March 2015 cost*
$83,908
*All hosting costs are paid for through corporate partnerships.
100% of public donations go to the projects we fund.

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WE COULD DO
IT ALL AGAIN TOMORROW
Serverless services cost
$92

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comicrelief.com/donate

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Closing remarks

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Best practices
Automate everything
Decompose for agility
Standardized tools
Infrastructure as code

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Steps start migrating
1 – Do the foundational work
2 – Move your monolith to the cloud if needed
3 – Find the seams for your code
4 – Organize the data layer
5 – Move the code to serverless
6 – Break the database
7 – Break the APIs
8 – Repeat from step 5 until 7 until you are done

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Thank you!
Marcia Villalba
@mavi888uy