AWS ECS blue-green Deployment for Github Actions

This action deploys weighted DNS blue-green ECS cluster. It collects Route53 and ECS autoscaling information needed for the deployment.

ECS blue-green deploy consist of 5 steps.

1. Get blue-green status from Route53
   • prepare the route53 record JSONs
   • determine the current primary/secondary services
   • determine the current min/max capacity for primary/secondary services
2. Scale up original secondary cluster
3. Download and update task-definition with new ECR image-id, then upload back to AWS
   • Note: This action does not cover this step!
4. Update Route53 weight for blue-green
5. Scale down original primary cluster

Table of Contents

• Requirements
• Usage
• Parameters
  • Inputs
  • Outputs
• License

Requirements

Your Github repository will need to access AWS, I recommend going with OpenID Connect instead of AWS credentials. You can find more details from Terraform and Github Actions without AWS Credentials.

In your workflow yaml file, you will need the following blocks.

env:
  AWS_ACCOUNT_ID_QA: 123456789012
  AWS_DEFAULT_REGION: us-west-2
  AWS_DEFAULT_OUTPUT: json

permissions:
  id-token: write
  contents: write
  actions: read

Under the steps section, configure AWS credentials via assume-role.

      - name: Configure AWS credentials [QA]
        uses: aws-actions/configure-aws-credentials@v1
        with:
          role-to-assume: arn:aws:iam::${{ env.AWS_ACCOUNT_ID_QA }}:role/qa-github-actions
          aws-region: ${{ env.AWS_DEFAULT_REGION }}

Usage

These environment variables need to be set in the action yml file in order to work properly.

Variable	Description
HOSTED_ZONE_ID	DNS zone ID (Z123456789ABC1)
ZONE_NAME	DNS domain name (rest-service.qa.my-company.com.)
ECS_CLUSTER	ECS cluster name
SERVICE_BLUE	First ECS service name
SERVICE_GREEN	Second ECS service name

env:
  HOSTED_ZONE_ID: Z123456789ABC1
  ZONE_NAME: rest-service.qa.my-company.com.
  ECS_CLUSTER: qa-default-01
  SERVICE_BLUE: qa-rest-service-blue
  SERVICE_GREEN: qa-rest-service-green

Step 1: We use get-blue-green-info to get all the weighted DNS and ECS information.

      - name: Get blue-green status
        uses: "cwong47/action-deploy-ecs-blue-green@latest"
        id: get-blue-green-info
        with:
          action: get-blue-green-info
          hosted_zone_id: ${{ env.HOSTED_ZONE_ID }}
          zone_name: ${{ env.ZONE_NAME }}
          ecs_service_blue: ${{ env.SERVICE_BLUE }}
          ecs_service_green: ${{ env.SERVICE_GREEN }}
          ecs_cluster: ${{ env.ECS_CLUSTER }}

Step 2: Update the autoscale settings of the original secondary cluster to match the original primary cluster.

      - name: Scale up original secondary cluster
        uses: "cwong47/action-deploy-ecs-blue-green@latest"
        id: update-secondary-autoscale-capacity
        with:
          action: update-autoscale-capacity
          ecs_cluster: ${{ env.ECS_CLUSTER }}
          ecs_service: ${{ steps.get-blue-green-info.outputs.original_secondary_service }}
          min_capacity: ${{ steps.get-blue-green-info.outputs.original_primary_min_capacity }}
          max_capacity: ${{ steps.get-blue-green-info.outputs.original_primary_max_capacity }}

Step 3: Render task-definition using amazon-ecs-render-task-definition and amazon-ecs-deploy-task-definition.

Step 4: Update weighted DNS accordingly.

      - name: Update Route53 weight for blue-green [QA]
        uses: "cwong47/action-deploy-ecs-blue-green@latest"
        id: update-primary-dns-weight
        with:
          action: update-dns-weight
          hosted_zone_id: ${{ env.HOSTED_ZONE_ID }}
          primary_route53_json: ${{ steps.get-blue-green-info.outputs.pending_primary_json }}
          secondary_route53_json: ${{ steps.get-blue-green-info.outputs.pending_secondary_json }}

Step 5: Update the autoscale settings of the original primary cluster to match the original secondary cluster.

      - name: Scale down original primary cluster [QA]
        uses: "cwong47/action-deploy-ecs-blue-green@latest"
        id: update-primary-autoscale-capacity
        with:
          action: update-autoscale-capacity
          ecs_cluster: ${{ env.ECS_CLUSTER }}
          ecs_service: ${{ steps.get-blue-green-info.outputs.original_primary_service }}
          min_capacity: ${{ steps.get-blue-green-info.outputs.original_secondary_min_capacity }}
          max_capacity: ${{ steps.get-blue-green-info.outputs.original_secondary_max_capacity }}

Parameters

Inputs

Name	Description	Default	Required	Used by
action	What step to execute	null	true	all
dry_run	Dry run	false	false	all
hosted_zone_id	Hosted zone ID from Route53	null	false	get-blue-green-info|update-dns-weight
zone_name	Zone name from Route53	null	false	get-blue-green-info
ecs_service_blue	The "blue" cluster of your ECS service	null	false	get-blue-green-info
ecs_service_green	The "green" cluster of your ECS service	null	false	get-blue-green-info
set_identifier_pattern	Default is "blue|green"	blue|green	false	get-blue-green-info
primary_route53_json	Primary Route53 record in JSON format in base64 encoding	null	false	update-dns-weight
secondary_route53_json	Secondary Route53 record in JSON format in base64 encoding	null	false	update-dns-weight
ecs_cluster	The ECS cluster	null	false	get-blue-green-info|update-autoscale-capacity
ecs_service	The cluster of your ECS service	null	false	update-autoscale-capacity
min_capacity	Minimum capacity to autoscale the service	null	false	update-autoscale-capacity
max_capacity	Maximum capacity to autoscale the service	null	false	update-autoscale-capacity

Outputs

Name	Description
original_primary_zone_id	Original primary zone ID
original_secondary_zone_id	Original secondary zone ID
original_primary_service	Original primary service
original_secondary_service	Original secondary service
original_primary_min_capacity	Original primary minimum capacity for autoscale
original_secondary_min_capacity	Original secondary minimum capacity for autoscale
original_primary_max_capacity	Original primary maximum capacity for autoscale
original_secondary_max_capacity	Original secondary maximum capacity for autoscale
pending_primary_json	Pending primary JSON in base64 encoding
pending_secondary_json	Pending secondary JSON in base64 encoding

License

The source code for this project is released under the MIT License. This project is not associated with GitHub or AWS.