How to automatically run consul agent and registrator container on scaling ECS instance

Question

I have created a consul cluster of three nodes. Now I need to run consul agent and registrator containers and join consul agent with one of the consul server node whenever I up ECS instance or scale out ECS instance on which I'm running my micro services.

I have automated rest of the deployment process with rolling updates. But I have to manually start up consul agent and registrator whenever I scale out ECS instance.

Anyone have idea how can we automate this?

Answer 1

Create an ELB in front of you consul servers or an elastic IP so that it doesn't change.

Then in userdata:

#!/bin/bash
consul_host=consul.mydomain.local

#start the agent
docker run -it --restart=always -p 8301:8301 -p 8301:8301/udp -p 8400:8400 -p 8500:8500 -p 53:53/udp \
-v /opt/consul:/data -v /var/run/docker.sock:/var/run/docker.sock -v /etc/consul:/etc/consul -h \
$(curl -s http://169.254.169.254/latest/meta-data/instance-id) --name consul-agent progrium/consul \
-join $consul_host -advertise $(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)`

#start the registrator
docker run -it --restart=always -v /var/run/docker.sock:/tmp/docker.sock \
-h $(curl -s http://169.254.169.254/latest/meta-data/instance-id) --name consul-registrator \
gliderlabs/registrator:latest -ip $(curl -s http://169.254.169.254/latest/meta-data/local-ipv4) \
consul://$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4):8500

Note: this snippet assumes your setup is all locally reachable, etc. It's from the cloudformations from this blog post and this link

Answer 2

1. Create a task-definition with two containers, consul-client and registrator.
2. aws ecs start-task in your userdata.

This AWS post focuses on this.

edit : Since you mentioned ECS instance, I assume you already have the necessary IAM role set for the instance.