Advanced Task Scheduling with Amazon ECS

© 2016, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Julien Simon
Principal Technical Evangelist, AWS
@julsimon
Advanced Task Scheduling "
with Amazon ECS
(CON307 revisited)

Docker on Amazon Web Services
Amazon EC2 Container Service (ECS)
•  https://aws.amazon.com/ecs/
•  Launched in 04/2015
•  No additional charge

Amazon EC2 Container Registry (ECR)
•  https://aws.amazon.com/ecr/
•  Launched in 12/2015
•  Free tier: 500MB / month for a year
•  $0.10 / GB / month + outgoing trafﬁc
ECS & ECS are available in 11 regions (US, EU, APAC)

Container Partners
https://aws.amazon.com/containers/partners/

Companies
Selected ECS customers

The problem

Given a certain amount of
computing power and memory,

how can we best manage
an arbitrary number of apps
running in Docker containers?
http://tidalseven.com

Amazon ECS: Under the Hood
ALB ALB
AZ 1 AZ 2
user / scheduler
https://github.com/aws/amazon-ecs-agent
http://www.allthingsdistributed.com/2015/07/under-the-hood-of-the-amazon-ec2-container-service.html

Case study: Coursera
https://www.youtube.com/watch?v=a45J6xAGUvA
Coursera deliver Massive Open Online Courses (14 million students, 1000+
courses). Their platform runs a large number of batch jobs, notably to grade
programming assignments. Grading jobs need to run in near-real time while
preventing execution of untrusted code inside the Coursera platform.

After trying out some other Docker solutions, Coursera have picked Amazon
ECS and have even written their own scheduler.

“Amazon ECS enabled Coursera to focus on releasing new software !
rather than spending time managing clusters” - Frank Chen, Software
Engineer

Scheduling on ECS: two options so far
1.  Let ECS handle scheduling through Services
•  Task Definition
•  ECS equivalent of the Docker Compose file
•  Versioned
•  cpu_shares, mem_limit
•  Number of containers
2.  Implement a custom scheduler with the ECS API
•  Describe cluster state
•  Select a specific ECS instance according to custom logic
•  Run task on this instance

Placement Engine: giving developers more control
ALB ALB
AZ 1 AZ 2
user / scheduler
Placement Engine
Placement Constraints
Placement Strategies

Placement Constraints
Name Example
AMI ID attribute:ecs.ami-id == ami-eca289fb
Availability Zone attribute:ecs.availability-zone == us-east-1a
Instance Type attribute:ecs.instance-type == t2.small
Distinct Instances type=“distinctInstance”
Custom attribute:stack == prod

Example: Constraint on Instance Family/Type

Example: Constraint on Availability Zone

Example: Combining Multiple Constraints

Binpacking Spread Affinity Distinct Instance

Placement Strategy Chaining
Spread tasks across Zones
and Binpack within each Zone

Anatomy of Task Placement
Cluster Constraints
Custom Constraints
Apply Filter
Satisfy CPU, memory, and port requirements
Filter for location, instance-type, AMI, or custom
attribute constraints
Identify instances that meet spread or binpack
placement strategy
Select final container instances for placement

g2.2xlarge t2.small g2.2xlarge g2.2xlarge
Placement: Targeting Instance Type

g2.2xlarge t2.small t2.micro t2.medium
t2.medium t2.small g2.2xlarge
t2.small
t2.small t2.medium
us-east-1aus-east-1d
Placement: Targeting Instance Type & Zone

t2.medium t2.small g2.2xlarge t2.small
g2.2xlarge t2.medium
t2.micro t2.small
us-east-1c
Placement: Availability Zone Spread

t2.micro t2.small
us-east-1c
Placement: Spread across Zone and Binpack

t2.micro t2.small
us-east-1c
Placement: Afﬁnity and Anti-Afﬁnity

t2.medium t2.small t2.small
t2.medium t2.micro t2.small
us-east-1c
Placement: Multiple Services on a Cluster

t2.medium g2.2xlarge t2.micro t2.small
t2.small t2.small g2.2xlarge t2.small
t2.small t2.small
g2.2xlarge t2.small
Placement: Services – Distinct Instances

ALB ALB
AZ 1 AZ 2
user / scheduler
Placement Engine
Event Stream

Handling ECS events with Blox
scheduler cluster state service

ALB ALB
AZ 1 AZ 2
user / scheduler
Scheduler
Cluster State Service
Placement Engine
Event Stream

t2.small t2.small t2.small
Blox: Daemon Scheduler
scheduler cluster state service

Creating Clusters
Create an ECS cluster for Blox
CF template: https://github.com/blox/blox/blob/dev/deploy/aws/conf/cloudformation_template.json
à  CloudWatch Event Rule + SQS queue
à  Daemon Scheduler + Cluster State Service + etcd
à  REST API exposing the Daemon Scheduler API
Create another ECS cluster managed by Blox
$ ecs-cli configure --cluster WebCluster --region ap-southeast-1
$ ecs-cli up --keypair admin --capability-iam --size 3 --instance-type t2.micro
Invoke the scheduler API
‘demo-cli’ tool: https://github.com/blox/blox/tree/dev/deploy/demo-cli

Listing Task Deﬁnitions
Grab the ARN for an nginx Task Deﬁnition, which the
Daemon Scheduler will manage on ‘WebCluster’.
$ ./list-task-definitions.py --region ap-southeast-1
== Blox Demo CLI - List Task Definitions ==
{
"taskDefinitionArns": [
"arn:aws:ecs:ap-southeast-1:ACCOUNT:task-definition/BloxFramework:2",
"arn:aws:ecs:ap-southeast-1:ACCOUNT:task-definition/nginx:1",
"arn:aws:ecs:ap-southeast-1:ACCOUNT:task-definition/nginx:2"
]
}

Creating an Environment
$ ./blox-create-environment.py --environment WebEnvironment --cluster
WebCluster --task-definition "arn:aws:ecs:ap-southeast-1:ACCOUNT:task-
definition/nginx:2" --stack Blox --apigateway --region ap-southeast-1
== Blox Demo CLI - Create Blox Environment ==
HTTP Response Code: 200
{
"taskDefinition": "arn:aws:ecs:ap-southeast-1:ACCOUNT:task-definition/
nginx:2",
"deploymentToken": "17248257-08ec-4438-888f-e0ac28397653",
"health": "healthy",
"name": "WebEnvironment",
"instanceGroup": {
"cluster": "arn:aws:ecs:ap-southeast-1:ACCOUNT:cluster/WebCluster"
}
}

Listing Environments
$ ./blox-list-environments.py --stack Blox --apigateway --region ap-southeast-1
== Blox Demo CLI - List Blox Environments ==
{
"items": [
{
nginx:2",
"deploymentToken": "17248257-08ec-4438-888f-e0ac28397653",
"health": "healthy",
"name": "WebEnvironment",
"instanceGroup": {
"cluster": "arn:aws:ecs:ap-southeast-1:ACCOUNT:cluster/WebCluster"
}
}
]
}

Creating a Deployment
$ ./blox-create-deployment.py --environment WebEnvironment --deployment-token
"17248257-08ec-4438-888f-e0ac28397653" --stack Blox --apigateway --region ap-
southeast-1
== Blox Demo CLI - Create Blox Deployment ==
{
"status": "pending",
"environmentName": "WebEnvironment",
"id": "7a05ea99-27a9-4339-a7a6-f4120065aea3",
"failedInstances": [],
"taskDefinition": "arn:aws:ecs:ap-southeast-1:613904931467:task-definition/
nginx:2”
}

Listing Deployments
$ ./blox-list-deployments.py --environment WebEnvironment --stack Blox --
apigateway --region ap-southeast-1
== Blox Demo CLI - List Blox Deployments ==
{
"items": [
{
"status": "completed",
"environmentName": "WebEnvironment",
"id": "7a05ea99-27a9-4339-a7a6-f4120065aea3",
"failedInstances": [],
nginx:2"
}
]
}

Scaling a Deployment
$ ecs-cli ps
Name State Ports TaskDefinition
26313cbe-d929-49de-9cc3-873bf5f32a91/nginx RUNNING nginx:2
98442432-fd5c-434d-b93c-0737bd06aaab/nginx RUNNING nginx:2
ce9bf217-4b34-4f31-9c7b-a8c3402f1ffd/nginx RUNNING nginx:2
$ ecs-cli scale --size 4 --capability-iam
$ ecs-cli ps
Name State Ports TaskDefinition
26313cbe-d929-49de-9cc3-873bf5f32a91/nginx RUNNING nginx:2
98442432-fd5c-434d-b93c-0737bd06aaab/nginx RUNNING nginx:2
c404ac9a-0948-4cc8-b5b0-2238ccdf4035/nginx RUNNING nginx:2
ce9bf217-4b34-4f31-9c7b-a8c3402f1ffd/nginx RUNNING nginx:2

Additional resources
Tech articles by Werner Vogels, CTO, Amazon.com
http://www.allthingsdistributed.com/2014/11/amazon-ec2-container-service.html
http://www.allthingsdistributed.com/2015/04/state-management-and-scheduling-with-ecs.html"
http://www.allthingsdistributed.com/2015/07/under-the-hood-of-the-amazon-ec2-container-service.html

Blox
https://blox.github.io/

Amazon ECS videos @ AWS re:Invent 2016
https://aws.amazon.com/blogs/compute/amazon-ec2-container-service-at-aws-reinvent-2016-wrap-up/

Thank you!
Julien Simon
Principal Technical Evangelist, AWS
@julsimon

Advanced Task Scheduling with Amazon ECS

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