5.7 KiB
Architecture
ECS integration relies on CloudFormation to manage AWS resrouces as an atomic operation. This document describes the mapping between compose application model and AWS components
Overview
This diagram shows compose model and on same line AWS components that get created as equivalent resources
+----------+ +-------------+ +-------------------+
| Project | . . . . . . . . . . . . . . | Cluster | . . . . . . . | LoadBalancer |
+-+--------+ +-------------+ +-------------------+
|
| +----------+ +-------------++-------------------+ +-------------------+
+----+ Service | . . . . . . . . . . | Service || TaskDefinition | | TargetGroup |
| +--+-------+ +-------------++-------------------+-+ +-------------------+
| | | TaskRole |
| | +-------------------+-+
| | x-aws-role, x-aws-policies . . . . . . . . | TaskExecutionRole |
| | +-------------------+
| | +---------+
| +--+ Deploy |
| | +---------+ +-------------------+
| | x-aws-autoscaling . . . . . . | ScalableTarget |
| | +-------------------+---+
| | | ScalingPolicy |
| | +-------------------+-+
| | | AutoScalingRole |
| | +-------------------+
| |
| | +---------+ +-------------+ +-------------------+
| +--+ Ports | . . . . . . . | IngressRule +-----+ | Listener |
| | +---------+ +-------------+ | +-------------------+
| | |
| | +---------+ +---------------+ +------------------+
| +--+ Secrets | . . . . . . . | InitContainer | |TaskExecutionRole |
| | +---------+ +---------------+ +------------+-----+
| | | |
| | +---------+ | |
| +--+ Volumes | | |
| | +---------+ | |
| | | |
| | +---------------+ | | +-------------------+
| +--+ DeviceRequest | . . . . . . . . . . . . . . . | . . . . | . . . | CapacityProvider |
| +---------------+ | | +-------------------+--------+
| | | | AutoscalingGroup |
| +------------+ +---------------+ | | +---------------------+
+---+ Networks | . . . . . . . . . | SecurityGroup +---+ | | LaunchConfiguration |
| +------------+ +---------------+ | +---------------------+
| |
| +------------+ +---------------+ |
+---+ Secret | . . . . . . . . . | Secret +--------------+
+------------+ +---------------+
Each compose application service is mapped to an ECS Service. A TaksDefinition is created according to compose definition.
Actual mapping is constrained by both Cloud platform and Fargate limitations. Such a TaskDefinition is set with a single container,
according to the compose model which doesn't offer a syntax to support sidecar containers.
An IAM Role is created and configured as TaskRole to grant service access to additional AWS resources when required. For this
purpose, user can set x-aws-policies or define a fine grained x-aws-role IAM role document.
Service's ports get mapped into security group's IngressRules and load balancer Listeners.
Compose application whith HTTP services only (using ports 80/443 or x-aws-protocol set to http) get an Application Load Balancer
created, otherwise a Network Load Balancer is used.
A TargetGroup is created per service to dispatch traffic by load balancer to the matching containers
Secrets bound to a service get translated into an InitContainer added to the service's TaskDefinition. This init container is
responsible to create a /run/secrets file for secret to match docker secret model and make application code portable.
A TaskExecutionRole is also created per service, and is updated to grant access to bound secrets.
Services using a GPU (DeviceRequest) get the Cluster extended with an EC2 CapacityProvider, using an AutoscalingGroup to manage
EC2 resources allocation based on a LaunchConfiguration. The latter uses ECS recommended AMI and machine type for GPU.
Service to declare deploy.x-aws-autoscaling get a ScalingPolicy created targeting specified the configured CPU usage metric