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| <modulesynopsis metafile="mod_heartbeat.xml.meta"> |
| |
| <name>mod_heartbeat</name> |
| <description>Sends messages with server status to frontend proxy</description> |
| <status>Experimental</status> |
| <sourcefile>mod_heartbeat</sourcefile> |
| <identifier>heartbeat_module</identifier> |
| <compatibility>Available in Apache 2.3 and later</compatibility> |
| |
| <summary> |
| <p> <module>mod_heartbeat</module> sends multicast messages to a <module>mod_heartmonitor</module> listener |
| that advertises the servers current connection count. Usually, <module>mod_heartmonitor</module> |
| will be running on a proxy server with <module>mod_lbmethod_heartbeat</module> loaded, which allows |
| <directive module="mod_proxy">ProxyPass</directive> to use the "heartbeat" <em>lbmethod</em> inside |
| of <directive module="mod_proxy">ProxyPass</directive>.</p> |
| <p> |
| <module>mod_heartbeat</module> itself is loaded on the origin server(s) that serve requests |
| through the proxy server(s). |
| </p> |
| |
| <note type="warning"> |
| To use <module>mod_heartbeat</module>, |
| <module>mod_status</module> and <module>mod_watchdog</module> |
| must be either a static modules or, if a dynamic module, must |
| be loaded before <module>mod_heartbeat</module>. |
| </note> |
| |
| </summary> |
| |
| <section id="consuming"> |
| <title>Consuming mod_heartbeat Output</title> |
| <p> |
| 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. |
| </p> |
| |
| <example><title>An Example Packet</title> |
| v=1&ready=75&busy=0 |
| </example> |
| |
| <p> |
| Consumers should handle new variables besides busy and ready, |
| separated by '&', being added in the future. |
| </p> |
| |
| </section> |
| |
| <directivesynopsis> |
| <name>HeartbeatAddress</name> |
| <description>Multicast address for heartbeat packets</description> |
| <syntax>HeartbeatAddress <var>addr:port</var></syntax> |
| <default>disabled</default> |
| <contextlist><context>server config</context></contextlist> |
| |
| <usage> |
| <p>The <directive>HeartbeatAddress</directive> directive specifies the |
| multicast address to which <module>mod_heartbeat</module> will send |
| status information. This address will usually correspond to a configured |
| <directive module="mod_heartmonitor">HeartbeatListen</directive> on a |
| frontend proxy system.</p> |
| <highlight language="config"> |
| HeartbeatAddress 239.0.0.1:27999 |
| </highlight> |
| </usage> |
| </directivesynopsis> |
| |
| </modulesynopsis> |