Slide 1

Slide 1 text

No content

Slide 2

Slide 2 text

A story about Vacation Tracker a 100% serverless startup

Slide 3

Slide 3 text

A story about Vacation Tracker a 100% serverless startup

Slide 4

Slide 4 text

A story about Vacation Tracker a 100% serverless startup

Slide 5

Slide 5 text

A story about Vacation Tracker a 100% serverless startup

Slide 6

Slide 6 text

A story about Vacation Tracker a 100% serverless startup

Slide 7

Slide 7 text

A story about Vacation Tracker a 100% serverless startup

Slide 8

Slide 8 text

In 2016 we decided to build a leave tracking system a leave tracking system

Slide 9

Slide 9 text

In 2016 we decided to build a leave tracking system To solve our own leave tracking problem

Slide 10

Slide 10 text

In 2016 we decided to build a leave tracking system 2017 To solve our own leave tracking problem

Slide 11

Slide 11 text

In 2016 we decided to build a leave tracking system 2017 2018 To solve our own leave tracking problem

Slide 12

Slide 12 text

The idea was simple: - track leave requests and number of remaining days - use some SSO, so we do not n!d to remember more passwords - connect to Slack so that we can have the info in Slack - connect to the calendar so we can subscribe to events

Slide 13

Slide 13 text

We were solving our problem but we were not sure if anyone else will use it

Slide 14

Slide 14 text

- startups - sma" companies - schools - non-profits - teams from enterprises - government organizations - churches

Slide 15

Slide 15 text

No content

Slide 16

Slide 16 text

The number of unique users by December 1st 263623

Slide 17

Slide 17 text

The dashboard

Slide 18

Slide 18 text

Slack

Slide 19

Slide 19 text

Microsoft Teams

Slide 20

Slide 20 text

The architecture v0.1 A simple serverless bot

Slide 21

Slide 21 text

No content

Slide 22

Slide 22 text

Why serverless?

Slide 23

Slide 23 text

From 1 to 101 Lambda Functions in Production Evolving a Serverless Architecture

Slide 24

Slide 24 text

@slobodan_ Before we continue…

Slide 25

Slide 25 text

Slobodan Stojanović CTO @ Cloud Horizon & CTO @ Vacation Tracker co-author of Serverless Applications with Node.js book AWS Serverless Hero https://slobodan.me

Slide 26

Slide 26 text

Why serverless?

Slide 27

Slide 27 text

s e r v e r l e s s

Slide 28

Slide 28 text

s e r v e r l e s s low

Slide 29

Slide 29 text

s e r v e r l e s s low xpensive

Slide 30

Slide 30 text

s e r v e r l e s s low xpensive endor lock-in

Slide 31

Slide 31 text

s e r v e r l e s s low xpensive endor lock-in

Slide 32

Slide 32 text

Serverless because: - Sma" team without devops experience - AUTO SCALABLE - Cheap - Fast to build a prototype - Secure

Slide 33

Slide 33 text

But it wasn't 100% "serverless"

Slide 34

Slide 34 text

No content

Slide 35

Slide 35 text

No content

Slide 36

Slide 36 text

- Quick and independent deployments - Easy to understand and maintain - Easy to onboard new people - Cheap Benefits:

Slide 37

Slide 37 text

The Cost: $0/month

Slide 38

Slide 38 text

Adding new features?

Slide 39

Slide 39 text

No content

Slide 40

Slide 40 text

No content

Slide 41

Slide 41 text

- Independent deployments - Hard to manage - Hard to scale - A bottleneck Downsides:

Slide 42

Slide 42 text

~ 100 paying teams

Slide 43

Slide 43 text

The architecture v1.0 A complex serverless application

Slide 44

Slide 44 text

Infrastructure-as-a-Code

Slide 45

Slide 45 text

Service Service (micro?) (micro?)

Slide 46

Slide 46 text

No content

Slide 47

Slide 47 text

~150 Lambda functions

Slide 48

Slide 48 text

FIRST MIGRATIONS (FROM AN OLD SERVICE TO A NEW ONE)

Slide 49

Slide 49 text

Finding a good architecture

Slide 50

Slide 50 text

- Everything is in IaaC CloudFormation - Replaced Node.js server with serverless services - Added TypeScript - Replaced MongoDB with DynamoDB Things we changed:

Slide 51

Slide 51 text

- independent deployments - Auto-scalable - Almost 100% uptime out-of-the-box - Sti" cheap Benefits:

Slide 52

Slide 52 text

- Storing state not events - Wasting time on less important things - Hard to onboard new developers - Many new services Downsides:

Slide 53

Slide 53 text

- Storing state not events - Wasting time on less important things - Hard to onboard new developers - Many new services - Developers don't like YAML :) Downsides:

Slide 54

Slide 54 text

~ 600 paying teams

Slide 55

Slide 55 text

The architecture v2.0 An event driven system

Slide 56

Slide 56 text

Finding a good architecture v2.0

Slide 57

Slide 57 text

Command Query Responsibility Segregation (CQRS)

Slide 58

Slide 58 text

Why CQRS?

Slide 59

Slide 59 text

Storing the state vs storing the events

Slide 60

Slide 60 text

- Ana created a location and moved John and Mike - Ana assigned Mike as an approver - Ana assigned a leave policy (20 PTO days per year) - John requested a leave, Ana approved - Ro"over, some unused days were transferred to the next year - Ana changed John's working w!k - Mike added some past leaves for John - Alex transferred John to another location with different policy - …

Slide 61

Slide 61 text

A quiz question: Calculate John's remaining PTO days for 2021

Slide 62

Slide 62 text

CQRS to the rescue

Slide 63

Slide 63 text

Mutation Event storage Subscription Query Read-only table EventBridge Business logic Business logic AWS AppSync

Slide 64

Slide 64 text

Mutation Event storage Subscription Query Read-only table EventBridge Business logic Business logic AWS AppSync

Slide 65

Slide 65 text

Mutation Event storage Subscription Query Read-only table EventBridge Business logic Business logic AWS AppSync

Slide 66

Slide 66 text

112 Lambda functions

Slide 67

Slide 67 text

- Fu"y Managed GraphQL - Less code - Better control - A" benefits from the previous architecture - Monorepo Benefits:

Slide 68

Slide 68 text

- More new services to learn - Velocity templates Downsides:

Slide 69

Slide 69 text

Challenges

Slide 70

Slide 70 text

Onboarding new developers

Slide 71

Slide 71 text

Current team - 4 developers (a" fu" stack, one new) - 1 Marketing - 1 Customer support - 1 Product manager - Some fr!lance support (marketing + design)

Slide 72

Slide 72 text

One environment per developer (serverless :))

Slide 73

Slide 73 text

No content

Slide 74

Slide 74 text

Good to start with

Slide 75

Slide 75 text

Testing

Slide 76

Slide 76 text

@slobodan_

Slide 77

Slide 77 text

@slobodan_

Slide 78

Slide 78 text

@slobodan_

Slide 79

Slide 79 text

@slobodan_

Slide 80

Slide 80 text

@slobodan_

Slide 81

Slide 81 text

@slobodan_

Slide 82

Slide 82 text

@slobodan_

Slide 83

Slide 83 text

@slobodan_

Slide 84

Slide 84 text

@slobodan_

Slide 85

Slide 85 text

Migrations

Slide 86

Slide 86 text

@slobodan_

Slide 87

Slide 87 text

@slobodan_

Slide 88

Slide 88 text

@slobodan_

Slide 89

Slide 89 text

@slobodan_ But, how does this look like?

Slide 90

Slide 90 text

@slobodan_ describe('DynamoDB repository', () => { describe('unit', () => { ... }) describe('integration', () => { beforeAll(() => { // Create test DB }) afterAll(() => { // Destroy test DB }) // Tests }) })

Slide 91

Slide 91 text

@slobodan_ beforeAll(async () => { const params = { ... } await dynamoDb.createTable(params).promise() await dynamoDb.waitFor('tableExists', { TableName: tableName }).promise() })

Slide 92

Slide 92 text

@slobodan_ afterAll(async () => { await dynamoDb.deleteTable({ TableName: tableName }).promise() await dynamoDb.waitFor('tableNotExists', { TableName: tableName }).promise() })

Slide 93

Slide 93 text

Debugging and monitoring

Slide 94

Slide 94 text

No content

Slide 95

Slide 95 text

No content

Slide 96

Slide 96 text

Cost

Slide 97

Slide 97 text

Total cost from 2018: ~$7000

Slide 98

Slide 98 text

$5000 AWS credits ~$2000 paid

Slide 99

Slide 99 text

The most expensive bug: ~$3200

Slide 100

Slide 100 text

No content

Slide 101

Slide 101 text

We have many other smaller challenges, but we are happy with serverless!

Slide 102

Slide 102 text

@slobodan_

Slide 103

Slide 103 text

@slobodan_ Summary

Slide 104

Slide 104 text

@slobodan_ • Evolve your architecture with your product • Pick a good architecture, it helps you to keep your migration and onboarding costs low • Think about onboarding new team members • Hexagonal architecture is a nice fit for serverless apps • CQRS is also A nice fit for serverless apps and excellent fit for Vacation Tracker • Test your integrations (and app in general) • Testing is not enough, you'll need monitoring and error tracking

Slide 105

Slide 105 text

@slobodan_

Slide 106

Slide 106 text

@slobodan_ https://slobodan.me/subscribe