set it and forget it: auto scaling target tracking policies - aws online tech talks

© 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.

Andre Dufour, AWS Automation and Messaging

November 6, 2017

Set it and Forget it: Auto Scaling Target Tracking Policies


Auto Scaling groupAuto Scaling group

Fleet management Dynamic Scaling

Elastic Load Balancing

EC2 instances

Elastic Load Balancing

EC2 instances

What is Auto Scaling?

CPU utilization

© 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.© 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.

Dynamic scaling


Dynamic scaling policy types

Simple scaling — single scaling adjustment

Step scaling — adjustment depends on size of alarm breach

Target tracking scaling — target value for a specific metric


Target tracking scaling policies

Set itand forget it

Simplicity

Speed


Target tracking in action: scaling out

ELB

EC2 Instances

Traffic 5

10

15

20

25

30

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Inst

ance

s

CP

U

Target Utilization CPU Utilization Instances

Traf

fic

Time


Setting up target tracking scaling policies


Horizontally scalable applications use cases

- Load balanced applications

- Batch data processing applications


Load-balanced applications

ELB

Auto Scaling group

AvailabilityZone A

AvailabilityZone B

Load Balancing Layer

Compute Layer

Data Layer DynamoDB

CPU


Target tracking a load-balanced application:Step 1: Picking the metric

- Application Load Balancer Request Count per Target

- Average CPU Utilization


Target tracking a load-balanced application:Step 2: Setting the target

How many requests can you handle per instance?

How quickly do your EC2 instances launch before they start receiving traffic?

How fast does the traffic ramp?


Batch data processing applications

AvailabilityZone A

AvailabilityZone B

Producer

Consumer

…

EC2 Instance

Queue Simple Queue Service

Requests

Auto Scaling group


=𝑄𝑢𝑒𝑢𝑒 𝑆𝑖𝑧𝑒 (𝐴𝑝𝑝𝑟𝑜𝑥𝑖𝑚𝑎𝑡𝑒𝑁𝑢𝑚𝑏𝑒𝑟𝑂𝑓𝑀𝑒𝑠𝑠𝑎𝑔𝑒𝑠𝑉𝑖𝑠𝑖𝑏𝑙𝑒)

𝐹𝑙𝑒𝑒𝑡 𝑆𝑖𝑧𝑒 (𝑅𝑢𝑛𝑛𝑖𝑛𝑔 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝑜𝑓 𝑡ℎ𝑒 𝑓𝑙𝑒𝑒𝑡)Backlog Per Capacity Unit


Target tracking a batch data processing application:Step 1: Creating a custom metric


Target tracking a batch data processing application:Step 2: Setting a target

=𝐴𝑐𝑐𝑒𝑝𝑡𝑎𝑏𝑙𝑒 𝑀𝑒𝑠𝑠𝑎𝑔𝑒 𝑃𝑟𝑜𝑐𝑒𝑠𝑠𝑖𝑛𝑔 𝐿𝑎𝑡𝑒𝑛𝑐𝑦

𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑇𝑖𝑚𝑒 𝑡𝑜 𝑃𝑟𝑜𝑐𝑒𝑠𝑠 𝑎 𝑀𝑒𝑠𝑠𝑎𝑔𝑒

Acceptable Backlog per Capacity Unit



Processing SLA = 10 Seconds

Processing time per message = 0.1 seconds

Acceptable backlog = 10/0.1 = 100 messages

TARGET = 100 messages

Target tracking a batch data processing application:Example


Target = 100 messages

Queue size = 1000

Fleet size = 10

Actual backlog per capacity unit = 1000/10 = 100

Target = Actual No scaling action

Target tracking a batch data processing application:Example continued


Target = 100 messages

Queue size = 1500

Fleet size = 10


Target < Actual Auto Scaling adds 5 instances

Queue size = 1500

Fleet size (new) = 15


Target = Actual No scaling action

Target tracking a batch data processing application:Example continued


Other best practices


Setting the min/max size of the Auto Scaling group

Max

Cost you’re willing to incur for the application

Enough capacity to support peak load

Min

2-3 EC2 instance per ASG balanced across AZs to ensure 100% up time


Auto Scaling group

EC2 instances have longer bootstrapping timesUse scheduled scaling

Recurring scaling events

Schedule individual events

ELB

EC2 instances

Scaling event

Scaling event


Onboarding with dynamic scaling

Analyze historical trends

Choose the lower end of the range

Adjust as the application becomes more mature


Application Auto Scaling for other services

Fleet

EMR Instance Group

Scalable Target Scalable Dimension

Service TasksECS

Spot Fleet Request Spot InstancesEC2 Spot Fleet

AppStream 2.0

EMRCore nodesTask nodes

AppStream Instances

Tables and Global Secondary Indices (GSI)

Provisioned CapacityDynamoDB


Demo


Questions?


What are you Scaling? #smoothscaling

Twitter: @arwdufour


Thank you!aws.amazon.com/autoscaling/getting-started

set it and forget it: auto scaling target tracking policies - aws online tech talks

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