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