Type: action configuration parameter
This parameter allows to specify if actions should always be executed (“off,” the default) or only if the previous action is suspended (“on”). This parameter works hand-in-hand with the multiple actions per selector feature. It can be used, for example, to create rules that automatically switch destination servers or databases to a (set of) backup(s), if the primary server fails. Note that this feature depends on proper implementation of the suspend feature in the output module. All built-in output modules properly support it (most importantly the database write and the syslog message forwarder).
This selector processes all messages it receives (*.*). It tries to forward every message to primary-syslog.example.com (via tcp). If it can not reach that server, it tries secondary-1-syslog.example.com, if that fails too, it tries secondary-2-syslog.example.com. If neither of these servers can be connected, the data is stored in /var/log/localbuffer. Please note that the secondaries and the local log buffer are only used if the one before them does not work. So ideally, /var/log/localbuffer will never receive a message. If one of the servers resumes operation, it automatically takes over processing again.
We strongly advise not to use repeated line reduction together with ActionExecOnlyWhenPreviousIsSuspended. It may lead to “interesting” and undesired results (but you can try it if you like).
*.* @@primary-syslog.example.com $ActionExecOnlyWhenPreviousIsSuspended on & @@secondary-1-syslog.example.com # & is used to have more than one action for & @@secondary-2-syslog.example.com # the same selector - the multi-action feature & /var/log/localbuffer $ActionExecOnlyWhenPreviousIsSuspended off # to re-set it for the next selector
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