Docker on Amazon ECS using AWS CloudFormation & CLI

Devteds Episode #9

Create and run docker container on Amazon ECS using CloudFormation and CLI.

• Containerize a simple REST API application
• Use AWS CLI to create Amazon ECR repository
• Build docker image and push to ECR
• CloudFormation stack to create VPC, Subnets, InternetGateway etc
• CloudFormation stack to create IAM role
• CloudFormation stack to create ECS Cluster, Loadbalancer & Listener, Security groups etc
• CloudFormation stack to deploy docker container

Episode video link

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Terminal Window Logs

Code

mkdir ~/projs
git clone https://github.com/devteds/e9-cloudformation-docker-ecs.git docker-on-ecs
cd docker-on-ecs

Dockerize a simple app

# Run on local
docker build -t books-api ./app/
docker run -it -p 4567:4567 --rm books-api:latest
open http://localhost:4567/
open http://localhost:4567/stat
open http://localhost:4567/api/books

Push Docker Image to ECR

aws ecr create-repository --repository-name books-api
aws ecr get-login --no-include-email | sh
IMAGE_REPO=$(aws ecr describe-repositories --repository-names books-api --query 'repositories[0].repositoryUri' --output text)
docker tag books-api:latest $IMAGE_REPO:v1
docker push $IMAGE_REPO:v1

Create CloudFormation Stacks

aws cloudformation create-stack --template-body file://$PWD/infra/vpc.yml --stack-name vpc

aws cloudformation create-stack --template-body file://$PWD/infra/iam.yml --stack-name iam --capabilities CAPABILITY_IAM

aws cloudformation create-stack --template-body file://$PWD/infra/app-cluster.yml --stack-name app-cluster

# Edit the api.yml to update Image tag/URL under Task > ContainerDefinitions and,
aws cloudformation create-stack --template-body file://$PWD/infra/api.yml --stack-name api

Copy the BooksApiEndpoint value from api stack output on AWS Management Console. Make a request to that URL on browser or any REST client.

Need to deploy app changes?

There isn't a cleaner way to deploy application changes (container) with CloudFormation, especially if you prefer the same image tag (eg: latest, green, prod etc). There are a few different options,

• Use new image tag and pass that as parameter to CF stack (api.yml) to update-stack or deploy. Many don't prefer using new revision number for as tag.
• With CloudFormation, some prefer create-stack & delete-stack to manage zero-downtime blue-green deployments, not specifically for ECS. ECS does part of this but this is an option
• Use ECS-CLI if you like Docker Compose structure to define container services. This is interesting but I am not sure this is really useful.
• A little hack to register a new task definition revision and update the service using CLI. Refer the ./deploy_app.sh script.

# ./deploy_app.sh <CLUSTER NAME> <SERVICE NAME> <TASK FAMILY>
./deploy_app.sh bookstore books-service apis
# One executed, ECS Service update will take a few minutes for the new task / container go live

References

Find the resources and references on https://devteds.com/episodes/9-docker-on-amazon-ecs-using-cloudformation

• Blog on automation of docker build and ecs deployment - https://spin.atomicobject.com/2017/06/06/ecs-deployment-script/
• AWS ECS-CLI https://docs.aws.amazon.com/AmazonECS/latest/developerguide/ECS_CLI.html