This tool generates a HAproxy configuration file based on etcd, and then reloads gracefully HAproxy.

hadiscover is listening on a specific directory in etcd, and for each changes it re-generates the configuration and reloads graceully the server (using the -sf HAproxy flag).

It have been created to be used in parallel of my Dockreg tool which does Docker container registration in etcd (see my blog post).

For more information and for build instruction, please read my post about Service Discovery with HAproxy.

hadiscover uses a go text template to generate the haproxy configuration. For example:

global
    maxconn 4096

defaults
    log global
    mode    http
    option  httplog
    option  dontlognull
    retries 3
    redispatch
    maxconn 2000
    contimeout  5000
    clitimeout  50000
    srvtimeout  50000

frontend http-in
    bind *:8000
    default_backend http

backend http
{{range .}}     server {{.Name}} {{.Ip}}:{{.Port}} maxconn 32
{{end}}

The backend http part will be replaced by the list of available services retrieved in etcd.

The key name in etcd must have be formatted with the form host:port, for example: http://my-etcd-server:4001/keys/services/192.168.0.1:8000

hadiscover --config templatePath --etcd etcdServersList --ha pathToHAcommand --key etcdKey

Where:

• templatePath is the path to the configuration template
• etcdServersList is the list of etcd servers, like --etcd http://localhost:4001
• pathToHAcommand is the path to the HAproxy executable
• etcdKey is the key to watch changes for