Serverless Orchestration with AWS Step Functions - DevDay Austin 2017

© 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Akhtar Hossain
AWS Solutions Architect
Healthcare & Life Science
Sep 12th, 2017
Serverless Orchestration with
AWS Step Functions
Building a Composite Application

© 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved
I have this idea

Photo sharing app
Metadata
DynamoDB
Extract
metadata &
validate input
Recognize &
Auto Tag
Store
…
Pictures
S3 Bucket
Query &
Search

function handle(image, done, err) {
// metadata
var filemeta = extractImageMetadata(image);
if (!isSupported(metadata)) { err() };
var metadata = transformMetadata(filemeta);
done();
}
Extract the image metadata

// metadata
// image recognition
var labels = recognizePicture(image);
storeImageMetadata([metadata, labels])
done();
}
Use deep learning voodoo for object detection

// metadata
// generate thumbnail
generateThumbnail(image);
done();
}
Generate thumbnail and store in S3

// metadata
done();
}

// metadata
done();
}Everything should really be Microservices / Lambda functions, right?

// metadata
extractImageMetadata(image)
.then((img, meta) => isSupported(metadata) … )
.then((img, meta) => transform(metadata) … )
.then((img, meta) => recognizePicture(img) … )
.then((img, meta, labels) => storeImageMetadata … )
.then((img, meta, labels) =>
generateThumbnail(image) … );
}
Make sure we have our callbacks

function handle(image) {
// metadata
return extractImageMetadata(image)
.then((img, meta) => rekognizePicture(img) … )
}
What happens if that line fails?

// metadata
}
Can these two be done in parallel?

// metadata
}
This code is “dumb main function” (but hard to get right)
ExtractImageMetadata
ImageTypeCheck
TransformMetadata
Rekognition
StoreMetadata
Thumbnail

// metadata
}
ImageTypeCheck
TransformMetadata
Rekognition
StoreMetadata
Thumbnail
Queues and Notification

// metadata
}
ImageTypeCheck
TransformMetadata
Rekognition
Thumbnail
StoreMetadata

ImageTypeCheck
TransformMetadata
Rekognition Thumbnail
StoreMetadata
Start
End

…
Photo sharing app
Pictures
S3 Bucket
Start Workflow
Lambda
Processing Workflow
Step Functions
Extract
Lambda
Recognize
Lambda
Store
Lambda
Metadata
DynamoDB
Object Detection
Rekognition

Demo

ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End
“I want to sequence functions”
“I want to run functions in parallel”
“I want to select functions based on data”
“I want to retry functions”
“I want try/catch/finally”
“I have code that runs for hours”
• Scales out
• Doesn’t lose state
• Deals with errors/timeouts
• Easy to build & operate
• Auditable

ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End
{
"StartAt": "ExtractImageMetadata",
"States": {
"ExtractImageMetadata": {
"Type": "Task",
"Next": “ImageTypeCheck”
},
…
}
}
Define in JSON and Then
Visualize in the Console

Execute One or One Million
ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End
ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End
ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End
ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End

Step Functions Building Blocks

ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End
Seven State Types
Task: a single unit of work
Synchronous: Lambda
{
"Type": "Task",
"Resource": "arn:aws:lambda:mars-ter …”,
…
}
}

ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End
Seven State Types
Asynchronous: “Activity Task”, Polled by workers
{
"Type": ”Task",
"Resource": "arn:aws:states:mars-ter …”,
…
}
}

API Actions on Activity Task
Register Activity Task - Returns ARN
Poll For task (by ARN)
Report Success
Report Failure
Report Heartbeat

Use Activity Task for Manual Approval
Step Functions
Poll
taskToken
Amazon
SES
Poller
Approver
Send success
taskToken
API
Gateway
https://aws.amazon.com/blogs/compute/
implementing-serverless-manual-approval-steps-in-aws-
step-functions-and-amazon-api-gateway/

Use Activity Task for Calling Asynchronous APIs
Step Functions
Poll
taskToken
Amazon
Elastic
Transcoder
Poller
SNS
Send success
taskToken
Lambda Amazon Confidential

ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End
Seven State Types
NotSupported
Choice: Adds branching logic
{
"Type": ”Choice",
”Choices": [{
”Variable": ”…",
”StringEquals": ”…",
”Next": ”…",
}
],
”Default": ”NotSupported",
…
}
}

ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End
Seven State Types
NotSupported
Fail: Stops an execution and mark as failure
Success: Stops an execution successfully

StoreMetadata
ImageTypeCheck
TransformMetadata
Start
End
Seven State Types
Task: A single unit of work
Parallel: fork and join data across tasks

Seven State Types
Choice: a single unit of work
Pass: passes inputs to its outputs
ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End

Document Processing

Seven State Types
Choice: a single unit of work
Pass: passes inputs to its outputs
Wait: wait until n seconds.
ImageTypeCheck
TransformMetadata
StoreMetadata
Start
End

Use Wait + Choice to Wait for AWS Batch Job
while:
sleep (30)
if status=done:
break
https://aws.amazon.com/blogs/compute/building-high-throughput-
genomics-batch-workflows-on-aws-workflow-layer-part-4-of-4/

"Access Media": {
"Type": "Task",
"Resource": "arn:aws:lambda:eu-central-1:123456789012:function:FindMedia",
"TimeoutSeconds": 2,
"Next": "Graceful Exit",
"Retry": [
{
"ErrorEquals": [ "States.Timeout" ],
"IntervalSeconds": 2, "MaxAttempts": 2, "BackoffRate": 1.5
}
],
"Catch": [
{ "ErrorEquals": [ "States.ALL" ], "Next": "Clean Up" }
]
},

Use Cases

With AWS Step Functions, we can easily change and iterate
on the application workflow of our food delivery service in
order to optimize operations and continually improve
delivery times. AWS Step Functions lets us dynamically scale
the steps in our food delivery algorithm so we can manage
spikes in customer orders and meet demand.
Mathias Nitzsche, CTO, foodpanda
“

Order Fulfillment

With AWS Step Functions, it was easy to build a multi-step product
updating system to ensure our database and website always have the
latest price and availability information.
AWS Step Functions let us replace a manual updating process with an
automated series of steps, including built-in retry conditions and error
handling, so we can reliably scale before a big show, and keep pace
with rapidly changing fashions.
Jared Browarnik, CTO, TheTake
“

Business Processes

AWS Step Functions makes it simple to coordinate information
from many different infrastructure systems using easy to design
workflows and create a more intelligent monitoring system for our
Platform as a Service (PaaS).
With AWS Step Functions, we can reliably automate monitoring
decisions and actions in order to reduce human intervention by
over 60%, which improves infrastructure operation productivity and
customer application availability on our platform.
Pedro Pimenta, VP R&D, OutSystems
“

13 AWS Lambda Task States
6 Choice States
1 Fail State
DevOps Automation

Integrate with other AWS services
• Create state machines and Activities with AWS
CloudFormation
• Call AWS Step Functions with Amazon API Gateway
• Start state machines in response to events, or on a
schedule, with Amazon CloudWatch Events
• Monitor state machine executions with Amazon CloudWatch
• Log API calls with AWS CloudTrail

Input/Output Processing

Input/Output Processing
State [x]"InputPath" "ResultPath" "OutputPath"
Input
Output

InputPath example
{
”s3key”:”apple.png”,
”timestamp”:12324
}
Input

InputPath example
{
}
"InputPath”:“$”
Input

InputPath example
{
}
State [x]"InputPath”:“$”
Input
Input received by state x:
{
}

InputPath example
"InputPath”:“$.s3key”
{
}
Input
{
}

InputPath example
State [y]"InputPath”:“$.s3key”
{
}
”apple.png”
Input
Input received by state y:
{
}

ResultPath example
{
}
Input
State [x]
State output:
{“type”: “png"}
"InputPath”
: “$”
”ResultPath”:“$”{ ”type”:”png}Output

ResultPath example
{
}
Input
State [x]
State output:
{“type”: “png"}
"InputPath”
: “$.s3key”
”ResultPath”:“$”{ ”type”:”png}Output
”ResultPath”:“$.metadata”
{
”timestamp”:12324,
“metadata”: {
“type”: “png"}
}
Output

Where does transient application
state live?
In the machine, in JSON texts
passing from state to state.A:
Q:

2.5¢
How much?
per thousand
state transitions
4,000 free
transitions/month
Free tier:

“I want to retry functions”
Is this you?
“I have code that runs for hours”
“I want to run functions in parallel”

Resources
• Github repo:
https://github.com/awslabs/lambda-refarch-imagerecognition
• Blogs, reference architectures, tutorials
https://aws.amazon.com/step-functions/getting-started
• Amazon States Language
https://states-language.net/spec.html
• Statelint
https://github.com/awslabs/statelint

Serverless Orchestration with AWS Step Functions - DevDay Austin 2017

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