11.2.7.1. Procedure – How conditional rewriting works

Purpose: 

The following procedure summarizes how conditional rewrite rules (rewrite rules that have the condition() parameter set) work. The following configuration snippet is used to illustrate the procedure:

rewrite r_rewrite_set{set("myhost", value("HOST") condition(program("myapplication")));};
log {
    source(s1);
    rewrite(r_rewrite_set);
    destination(d1);};

Steps: 

  1. The log path receives a message from the source (s1).

  2. The rewrite rule (r_rewrite_set) evaluates the condition. If the message matches the condition (the PROGRAM field of the message is "myapplication"), syslog-ng OSE rewrites the log message (sets the value of the HOST field to "myhost"), otherwise it is not modified.

  3. The next element of the log path processes the message (d1).