Presentation for GraphQL Wroclaw #2. Presented on 7th May 2019. Available on: https://www.facebook.com/mirumeelabs/videos/496722830863869/ Serverless is one of the hottest architectural patterns for developing cloud-native applications. GraphQL is rapidly becoming a standard for creating APIs in this environment. The AWS AppSync GraphQL service is a great way to get started with GraphQL in a serverless environment. During this presentation, you will learn how to create serverless GraphQL API applications based on this technology using cloud services like DynamoDB, Elasticsearch, Lambda and Cloudformation.

1. GraphQL AppSync 101

2. Agenda
Plan
What is AppSync?
What can you use it for?
What is it made of?
AWS AppSync types
Subscriptions
Security
Monitoring and logging
Pricing
Demo - existing data sources
Final thoughts
How to prototype really fast
2

3. What is AppSync?
AWS service that enables developers to easily build products
based on GraphQL.
Out of the box it supports many AWS products including:
● data storages
● lambdas
● cloud security
1
3

4. What can you use it for?2
4

5. What can you use it for?
Use cases:
◦ Exposing GraphQL API
◦ Real-time interaction applications
▫ Chats
▫ Collaboration
▫ News feed etc.
5

6. What is made of?3
6

7. Processing
7

8. Engine for:
◦ Security
◦ Processing requests
◦ Subscriptions
◦ Batch processes
Black box for developer.
GraphQL Proxy
8

9. GraphQL schema describing API contract
Schema
9

10. Types
◦ ID
◦ String
◦ Int
◦ Float
◦ Boolean
◦ AWSDate
◦ AWSTime
◦ AWSDateTime
◦ AWSTimestamp
◦ AWSEmail - Valid RFC 822
◦ AWSJSON - Valid RFC 8259
◦ AWSURL - Valid URL
◦ AWSPhone - Valid phone number (no spec in docs)
◦ AWSIPAddress - Valid IPv4 or IPv6
10

11. Types
AppSync supports interfaces and unions.
The caveat here is that you have to do is to append
‘__typename’ for type resolution
#foreach ($result in $context.result)
## Extract type name from the id field.
#set( $typeName = $result.id.split("-")[0] )
#set( $ignore = $result.put("__typename", $typeName))
#end
$util.toJson($context.result)
11

12. Data Sources
DynamoDB
AWS NoSQL
Elasticsearch
Search engine
Lambda
AWS Lambda function
RDS
Aurora - Relational Database
from AWS
HTTP
Any root http endpoint
None
Internal logic
12

13. Usually in GraphQL:
Responsible for serving requested data by field.
In AppSync:
Transforming request to data source request
and mapping data source response.
Resolvers
13

14. Unit resolver performs single operation on data
source.
It can also be a batch operation. But not for all
data sources. Supports DynamoDB and
Lambda.
Unit resolver
14

15. Allows executing
multiple operations
against one or more
data sources.
Composed of a list of
functions. Each
function is executed
in sequence and can
execute a single
operation on a data
source.
Pipeline resolver
15

16. Example use cases
◦ Load and transform fields based on the
requested format
◦ Custom roles setup application
Pipeline resolver
16

17. ◦ $ctx.stash
◦ $ctx.prev.result
◦ #return(data: Object) - breaks mapping template
with data
◦ $util.error - breaks execution with error
◦ $util.appendError - marks error without
interruption
Pipeline utilities
17

18. Functions are single operations for redundant
logic on the GraphQL Proxy as a part of
pipeline resolvers.
It can be our customer role check from previous
section
Functions
18

19. #set($validMinPrice =
$util.matches("d{1,3}[,.]?(d{1,2})?",$ctx.args.minPrice))
#if (!$validMinPrice)
$util.error("Provided price input is not valid.")
#end
{
"version": "2018-05-29",
"statements": [
"select * from Pets where price > :MIN"
],
"variableMap": {
":MIN": $ctx.args.minPrice
}
}
Functions
19

20. Testing and debugging resolvers
20

21. Subscription at scale for datasources not
supporting this feature.
AWS takes heavy-lifting and after successful
mutation it pushes notification to all subscribers
for you.
Subscriptions
21

22. Security4
22

23. Security
Cognito/OpenID
AWS auth service
supporting
standards like
◦ OAuth 2.0
◦ SAML 2.0
◦ OpenID Connect
OpenID Docs
IAM
For other AWS
services and users,
permissions per
resource / field
API KEY
Constant key sent
over x-api-key
header
23

24. Cognito
24

25. Cognito items access
25
type Query {
posts:[Post!]!
@aws_auth(cognito_groups: ["Bloggers", "Readers"])
}
type Mutation {
addPost(id:ID!, title:String!):Post!
@aws_auth(cognito_groups: ["Bloggers"])
}
Access per resource

26. IAM
26
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"appsync:GraphQL"
],
"Resource": [
"arn:aws:appsync:us-west-2:123456789012:apis/YourGraphQLApiId/types/Query/fields/<Field-1>",
"arn:aws:appsync:us-west-2:123456789012:apis/YourGraphQLApiId/types/Query/fields/<Field-2>",
"arn:aws:appsync:us-west-2:123456789012:apis/YourGraphQLApiId/types/Mutation/fields/<Field-1>",
"arn:aws:appsync:us-west-
2:123456789012:apis/YourGraphQLApiId/types/Subscription/fields/<Field-1>"
]
}
]
}
Access per resource

27. Monitoring and Logging5
27

28. We have 3 metrics:
◦ 4xx
◦ 5xx
◦ Latency - processing in ms
Monitoring
28

29. ◦ Request level
▫ Request and response HTTP headers
▫ GraphQL query
▫ Execution summary
▫ GraphQL subscriptions
◦ Field level
▫ Generated Request Mapping with source
and arguments for each field
▫ The transformed Response Mapping for
each field, which includes the data as a
result of resolving that field
▫ Tracing information for each field
Logging
29

30. There are 3 logging levels available:
◦ NONE - No field-level logs are captured
◦ ERROR - Logs fields that are in error
◦ ALL - The following information is logged for all
fields in the query:
▫ Field-level tracing information
▫ Request/response functions that got
resolved for each field
Logging levels
30

31. Pricing6
31

32. CRUD
◦ 250k FREE
◦ $4 per million Query and Data Modification
Operations
+
Data transfer fee charged at EC2 data
transfer rates
COSTS BY AWS DOCS
32

33. Real-time updates
◦ 250k FREE
◦ 600k connection minutes FREE
◦ $2 per million Real-time updates
Which are priced per 5kb payload of data
delivered. For example, an 8-KB payload is
metered as two real-time updates.
◦ $0.08 per million minutes of connection to
the AWS AppSync service
COSTS BY AWS DOCS
33

34. ◦ 2500 monthly active real-time app users
▫ 25 hours monthly / user
▫ 1000 sent & received events monthly / user
◦ Total cost
▫ Requests - sent messages:
2500 x 1000 x 4$/1M = 10$
▫ Connectivity:
2500 x 1500 x 0.08$ = 0.3$
▫ Data transfer:
1KB x 2.5M = 2.5 MKB = 2.4GB x 0.09$ = 0.21$
▫ Real-time updates:
2500 x 1000 x 2$/1M = 5$
▫ Total:
15.51$
Pricing example
34

35. Demo7
35

36. Our case
Routes on Elasticsearch -> Take a look
Price service on API Gateway -> Take a look
Airports on DynamoDB -> Take a look
36
Thumbnail URL generator -> Take a look

37. Demo - subscriptions8
37

38. Final thoughts9
38

39. Pros:
◦ Subscriptions
◦ Fast prototyping
◦ Nice tool for quickly mocking GraphQL at scale
◦ Serverless
Cons:
◦ VTL example from doc
◦ Testing
◦ Any middleware
Logging levels
39

40. How to prototype really fast?10
40
docs

41. CREDITS
Special thanks to all the people who made and
released these awesome resources for free:
◦ Presentation template by SlidesCarnival
◦ Photographs by Unsplash
41

42. Thanks!
ANY QUESTIONS?
42