Apache Module mod_heartmonitor

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Description:	Centralized monitor for mod_heartbeat origin servers
Status:	Experimental
Module Identifier:	heartmonitor_module
Source File:	mod_heartmonitor.c
Compatibility:	Available in Apache 2.3 and later

Summary

mod_heartmonitor listens for server status messages generated by mod_heartbeat enabled origin servers and makes their status available to mod_lbmethod_heartbeat. This allows ProxyPass to use the "heartbeat" lbmethod inside of ProxyPass.

This module uses the services of mod_slotmem_shm when available instead of flat-file storage. No configuration is required to use mod_slotmem_shm.

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

Bugfix checklist

HeartbeatListen Directive

Description:	multicast address to listen for incoming heartbeat requests
Syntax:	`HeartbeatListen addr:port`
Default:	`disabled`
Context:	server config
Status:	Experimental
Module:	mod_heartmonitor

The HeartbeatListen directive specifies the multicast address on which the server will listen for status information from mod_heartbeat-enabled servers. This address will usually correspond to a configured HeartbeatAddress on an origin server.

HeartbeatListen 239.0.0.1:27999

This module is inactive until this directive is used.

HeartbeatMaxServers Directive

Description:	Specifies the maximum number of servers that will be sending heartbeat requests to this server
Syntax:	`HeartbeatMaxServers number-of-servers`
Default:	`HeartbeatMaxServers 10`
Context:	server config
Status:	Experimental
Module:	mod_heartmonitor
Compatibility:	The value of 0 is accepted only in 2.4.55 and above

The HeartbeatMaxServers directive specifies the maximum number of servers that will be sending requests to this monitor server. It is used to control the size of the shared memory allocated to store the heartbeat info when mod_slotmem_shm is in use.

For using flat-file storage (without loading mod_slotmem_shm), this must be set to 0. The value must be either 0, or bigger or equals 10.

HeartbeatStorage Directive

Description:	Path to store heartbeat data when using flat-file storage
Syntax:	`HeartbeatStorage file-path`
Default:	`HeartbeatStorage logs/hb.dat`
Context:	server config
Status:	Experimental
Module:	mod_heartmonitor

The HeartbeatStorage directive specifies the path to store heartbeat data. This flat-file is used only when mod_slotmem_shm is not loaded and HeartbeatMaxServers is set to 0.