Amazon ECS on CoreOS

gistfile1.md

First, read the CoreOS page on ECS:

https://coreos.com/docs/running-coreos/cloud-providers/ecs/

Install the aws commandline tool:

which aws || pip install awscli

Make sure you have your AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY defined in your shell environment.

Create the ECS cluster:

aws ecs create-cluster --cluster-name Cosmos-Dev
{
    "cluster": {
        "clusterName": "Cosmos-Dev",
        "status": "ACTIVE",
        "clusterArn": "arn:aws:ecs:us-east-1:123456789012:cluster/My-ECS-Cluster"
    }
}

Install the global fleet unit for amazon-ecs-agent.service:

cat <<EOF > amazon-ecs-agent.service
[Unit]
Description=Amazon ECS Agent
After=docker.service
Requires=docker.service
[Service]
Environment=ECS_CLUSTER=My-ECS-Cluster
Environment=ECS_LOGLEVEL=warn
Environment=AWS_REGION=us-east-1
ExecStartPre=-/usr/bin/docker kill ecs-agent
ExecStartPre=-/usr/bin/docker rm ecs-agent
ExecStartPre=/usr/bin/docker pull amazon/amazon-ecs-agent
ExecStart=/usr/bin/docker run --name ecs-agent \
    --env=ECS_CLUSTER=${ECS_CLUSTER}\
    --env=ECS_LOGLEVEL=${ECS_LOGLEVEL} \
    --publish=127.0.0.1:51678:51678 \
    --volume=/var/run/docker.sock:/var/run/docker.sock \
    amazon/amazon-ecs-agent
ExecStop=/usr/bin/docker stop ecs-agent
[X-Fleet]
Global=true
EOF
fleetctl start amazon-ecs-agent.service

Now from a CoreOS host, we can query locally to enumerate the running ContainerInstances in our fleet:

fleetctl list-machines -fields=ip -no-legend | while read ip ; do \
    echo $ip $(ssh -n $ip curl -s http://169.254.169.254/latest/meta-data/instance-id) \
    $(ssh -n $ip curl -s http://localhost:51678/v1/metadata | \
      docker run -i realguess/jq jq .ContainerInstanceArn) ; \
  done

Which returns something like:

10.113.0.23 i-12345678 "arn:aws:ecs:us-east-1:123456789012:container-instance/674140ae-1234-4321-1234-4abf7878caba"
10.113.1.42 i-23456789 "arn:aws:ecs:us-east-1:123456789012:container-instance/c3506771-1234-4321-1234-1f1b1783c924"
10.113.2.66 i-34567891 "arn:aws:ecs:us-east-1:123456789012:container-instance/75d30c64-1234-4321-1234-8be8edeec9c6"

And we can query ECS and get the same:

$ aws ecs list-container-instances --cluster My-ECS-Cluster | grep arn | cut -d'"' -f2 | \
  xargs -L1 -I% aws ecs describe-container-instances --cluster My-ECS-Cluster --container-instance % | \
  jq '.containerInstances[] | .ec2InstanceId + " " + .containerInstanceArn'
"i-12345678 arn:aws:ecs:us-east-1:123456789012:container-instance/674140ae-1234-4321-1234-4abf7878caba"
"i-23456789 arn:aws:ecs:us-east-1:123456789012:container-instance/c3506771-1234-4321-1234-1f1b1783c924"
"i-34567891 arn:aws:ecs:us-east-1:123456789012:container-instance/75d30c64-1234-4321-1234-8be8edeec9c6"