haproxy combined with confd for HTTP load balancing

Usage

• HAProxy 1.5.x backed by Confd 0.9.0
• Uses zero-downtime reconfiguration (e.g - instead of harpy reload, which will drop all connections, will gradually transfer new connections to the new config)
• Added support for url rexeg (not reggae, damn you spell checker) for routing, in addition to the usual hostname pattern
• Added validation for existence of keys in backing kv store, to prevent failures

Create the paths allowing confd to find the services:

etcdctl mkdir "/haproxy-discover/services"
etcdctl mkdir "/haproxy-discover/tcp-services"

Depending on your needs, create one or more services or tcp-services. For instance, to create an http service named myapp linked to the domain example.org and load balancing on servers 1.2.3.4:80 (we'll call it nodeA) and 2.3.4.5:80 (called nodeB), run these commands:

etcdctl set "/haproxy-discover/services/myapp/domain" "example.org"
etcdctl set "/haproxy-discover/services/myapp/upstreams/nodeA" "1.2.3.4:80"
etcdctl set "/haproxy-discover/services/myapp/upstreams/nodeB" "2.3.4.5:80"

Start the container making sure to expose port 80 on the host machine

docker run -e ETCD_NODE=172.17.42.1:4001 -p 1000:1000 -p 80:8080 yaronr/haproxy-confd

To add an upstream node, let's say nodeB2, 2.3.4.5:90, you just have to run this, and the configuration should safely be updated !

etcdctl set "/haproxy-discover/services/myapp/upstreams/nodeB2" "2.3.4.5:90"

To remove an upstream server, let's say ... nodeB2 (added by mistake ?), just run

etcdctl rm "/haproxy-discover/services/myapp/upstreams/nodeB2"

To remove a service, and so a directory, you must type

etcdctl rmdir "/haproxy-discover/services/myapp"

The commands for a tcp-service are the same but with tcp-services instead of services

Have fun !