We met the configuration cache in Chapter 2, Getting Your First Notification, and we discussed ways to monitor it in Chapter 20, Zabbix Maintenance. While it helps a lot performance-wise, it can be a bit of a problem if we are trying to quickly test something. It is possible to force the Zabbix server to reload the configuration cache.

Run the following to display the Zabbix server options:

# zabbix_server --help

In the output, look for the runtime control options section:

-R --runtime-control runtime-option  Perform administrative functions  Runtime control options:
config_cache_reload  Reload configuration cache

Thus, reloading the server configuration cache can be initiated by the following:

# zabbix_server --runtime-control config_cache_reload
zabbix_server [2682]: command sent successfully

Examining the server log file will reveal that it has received the signal:

forced reloading of the configuration cache

In the background, the sending of the signal happens like this:

• The server binary looks up the default configuration file
• It then looks for the file specified in the PidFile option
• It sends the signal to the process with that ID

As discussed in Chapter 17, Using Proxies to Monitor Remote Locations, the great thing about this feature is that it's also supported for active Zabbix proxies. Even better, when an active proxy is instructed to reload its configuration cache, it connects to the Zabbix server, gets all the latest configuration, and then reloads the local configuration cache. If such a signal is sent to a passive proxy, it ignores the signal.

What if you have several proxies running on the same system—how can you tell the binary which exact instance should reload the configuration cache? Looking back at the steps that were taken to deliver the signal to the process, all that is needed is to specify the correct configuration file. If running several proxies on the same system, each must have its own configuration file already, specifying different PID files, log files, listening ports, and so on. Instructing a proxy that used a specific configuration file to reload the configuration cache would be this simple:

# zabbix_proxy -c /path/to/zabbix_proxy.conf --runtime-control config_cache_reload

Manually reloading the configuration cache is useful if we have a large Zabbix server instance and have significantly increased the CacheUpdateFrequency parameter.