Running Production High Availability Docker Services on CoreOS using Fleet, Flannel, Etcd, Confd & Nginx

• View the diagram of what's going on: https://drive.google.com/file/d/0B74l6vUHf9HrMzNrYUlyMm40RWs/view?usp=sharing

Tools used:

• coreos: server machine clustering via a shared cloud-config.yml
• etcd: key value store for service registration and discovery
• fleet: scheduling/failover of docker containers across coreos cluster
• flannel: Gives each docker container a unique ip that allows you to access the internal port (i.e. port 80 not 32679)
• confd: watch etcd for nodes arriving/leaving - template nginx configuration files / reload nginx on change

Docker Containers Used:

• willrstern/node-sample: a sample node.js app that simply echoes it's APPNAME environment variable
• willrstern/nginx-lb: a reusable nginx + confd image
  • uses confd to watch etcd and configure nginx to load balance for multiple docker containers
  • watches etcd keys/services/<servicename>/upstream/* and reloads nginx with an updated config when upstream nodes change
  • requires 2 env variables: SERVICE_NAME and ETCD so it knows which servicename to watch in etcd's registry
• willrstern/nginx-dns: an nginx + confd image for dynamic DNS based off of etcd keys/subdomain/* entries
  • requires 1 env variable: ETCD the ip address + port of the etcd instance it's watching