Apache Module mod_heartbeat

Description:	Sends messages with server status to frontend proxy
Status:	Experimental
ModuleIdentifier:	heartbeat_module
SourceFile:	mod_heartbeat
Compatibility:	Available in Apache 2.3 and later

Summary

mod_heartbeat sends multicast messages to a mod_heartmonitor listener that advertises the servers current connection count. Usually, mod_heartmonitor will be running on a proxy server with mod_lbmethod_heartbeat loaded, which allows ProxyPass to use the "heartbeat" lbmethod inside of ProxyPass.

mod_heartbeat itself is loaded on the origin server(s) that serve requests through the proxy server(s).

To use mod_heartbeat, mod_status and mod_watchdog must be either a static modules or, if a dynamic module, must be loaded before mod_heartbeat.

Topics

Consuming mod_heartbeat Output

Directives

HeartbeatAddress

Bugfix checklist

Consuming mod_heartbeat Output

Every 1 second, this module generates a single multicast UDP packet, containing the number of busy and idle workers. The packet is a simple ASCII format, similar to GET query parameters in HTTP.

An Example Packet

v=1&ready=75&busy=0

Consumers should handle new variables besides busy and ready, separated by '&', being added in the future.

HeartbeatAddress Directive

Description:	Multicast address for heartbeat packets
Syntax:	`HeartbeatAddress addr:port`
Default:	`disabled`
Context:	server config
Status:	Experimental
Module:	mod_heartbeat

The HeartbeatAddress directive specifies the multicast address to which mod_heartbeat will send status information. This address will usually correspond to a configured HeartbeatListen on a frontend proxy system.

HeartbeatAddress 239.0.0.1:27999