Published: Thursday, Jul 28, 2016 Last modified: Monday, May 27, 2024

Following up after [[ECS_questions]]

docker-compose.yml example

version: '2'
	image: kaihendry/count
	 - "80:8080"
	mem_limit: 1043333120
ECS instance resources

Mem limit was figured by taking Available Memory, t2.micro is 995 and getting bytes like so:

~$ echo $((995 << 20))

Assuming you have the docker-compose.yml ready and ecs-cli configured, start up the cluster of a EC2 instance running the service like so:

ecs-cli up --capability-iam --keypair example_sysadmin
ecs-cli compose service ps

Setting up the load balancer is manual

Create the service by attaching the load balancer to the task

export CLUSTER_NAME=default

aws --region ap-southeast-1 ecs create-service --service-name "ecscompose-service-count" \
	--cluster "$CLUSTER_NAME" \
	--task-definition "ecscompose-count" \
	--load-balancers "loadBalancerName=ecs-count,containerName=web,containerPort=9000" \
	--desired-count 1 --deployment-configuration "maximumPercent=100,minimumHealthyPercent=50" --role ecsServiceRole


ecs-cli down will not work until you remove the ELB So you need to terminate the instance manually if you want to save some money.

ecs-cli up by default will create a security group that you can’t ssh into.

Developer workflow

aws ecr get-login --profile example --region us-west-2
docker build -t website .
docker tag website:latest
docker push

Typically a 100mb upload

Then bring down the service and up the service like so:

Bringing down a service

ecs-cli compose service down

Will bring down the particular service. Note that it’s conceivable that many services run on an instance.

You can kill the entire cluster like ecs-cli down --force, but I don’t recommend that because the VPC will change when you re-establish it, so your previously manually set up load balancer will not work.

Current workaround is to manually terminal the EC2 instance from the Web console if I am not requiring it.

DNS failover

Notice that “Evaluate Target Health” is enough for the Failover rule to know the load balancer is out of action. You do not need a health check!

We fail over to Cloudfront since we require SSL to work.

Upgrade flow

Upgrading the container image

Running two instances with the container running on each and then doing a ecs-cli compose service up should upgrade the service I’m told, but I doubt it works. Some careful orchestration with Health limits.

Upgrading the EC2 instance image

Upgrading an instance basically means killing it and starting it again. I guess that would entail a scale event to launch a new instance. ssh to it to ensure it’s uptodate (security group permitting). And then decommission the old one by removing it from the load balancer.


No way to terminate last EC2 Instance in cluster:

$ ecs-cli scale --size 0 --capability-iam
INFO[0002] Waiting for your cluster resources to be updated
INFO[0003] Cloudformation stack status                   stackStatus=UPDATE_IN_PROGRESS
ERRO[0035] Failure event                                 reason= resourceType=AWS::CloudFormation::Stack
ERRO[0035] Error executing 'scale': Cloudformation failure waiting for 'UPDATE_COMPLETE'. State is 'UPDATE_ROLLBACK_COMPLETE'


  1. ecs-cli up --capability-iam --keypair spuul_sysadmin
  2. ecs-cli compose service up to create service
  3. Find VPC name
  1. Create ELB
  1. Create service from task and associate ELB
  2. Update Route 53 Failover record with ELB name in case things really go badly