Advanced logging configuration

If you want ultimate control over where log messages go, you can use this rule-based config format for logging. For most cases you will only need the simple logging formats.

This advanced format allows you give Prosody a list of logging destinations (console, file, syslog, etc.) and specify which messages should go to that destination. An example is worth a thousand words, so here is the default logging Prosody uses if you don't specify one in the config:

   log = {
            { to = "console" };
         }

That's right… one rule, it matches all messages and sends them to the 'console' sink.

So here's a better one, which is similar to the split logging output:

   log = {
          -- Log all error messages to prosody.err
          { levels = { min = "error" }, to = "file", filename = "/var/log/prosody/prosody.err" };
          -- Log everything of level "info" and higher (that is, all except "debug" messages)
          -- to prosody.log
          { levels = { min =  "info" }, to = "file", filename = "/var/log/prosody/prosody.log" };
         }

These rules have something new… a 'levels' option. To this you can provide a min/max level, or a list of levels, or a single level.

Here are some examples:

   levels = { min = "info" } -- Only match messages with a level of 'info' or higher
   levels = { max = "warn" } -- Exclude messages with a level higher that 'warn'
   levels = { min = "info", max = "warn" } -- The above combined, only match messages between 'info' and 'warn'
   levels = { "info", "warn", "error" } -- Only match these levels
   levels = "info" -- Only match 'info' messages, and nothing else

If any 'levels' specification is omitted then the rule will match messages from all levels.

You may build your own timestamp format, for example:

   log = {
          -- Log all error messages to prosody.err
          { levels = { min = "error" }, to = "file", timestamps = "%s", filename = "/var/log/prosody/prosody.err" };
          -- Log everything of level "info" and higher (that is, all except "debug" messages)
          -- to prosody.log
          { levels = { min =  "info" }, to = "file", timestamps = "%s", filename = "/var/log/prosody/prosody.log" };
         }

Ok, so now you got the hang of that, there's one more thing. You can also match on the 'source' of the message. You will see in log messages that they give the name of the module that generated them. This is most useful when combined with the 'nowhere' logging destination. Then you can easily silence certain log messages which you don't want to see:

   log = {
           { name = "modulemanager", to = "nowhere" }; -- Drop messages from modulemanager
           { to = "console" };
         }