We have Nginx as a reverse proxy in front of Tomcat. Both of them log access with ISO 8601 timestamps, but tomcat adds in milliseconds (which is part of the standard). So if Nginx gets a request and passes it onto Tomcat, the Nginx log might have a timestamp of "2015-10-29T00:37:02+00:00" and Tomcat will have a timestamp of "2015-10-29T00:37:02,106+0000" for the same access. I'm not concerned about the minor differences in formatting, but not having milliseconds (the ",106" part in the Tomcat log) is a problem because it prevents us from correlating the logs correctly.
Is there any way to make Nginx include milliseconds in it's logs?
Best Answer
Unfortunately, based on reading the source code to nginx, there doesn't seem to be a simple way to do this. You would need to post-process the logs (you could take the output of $msec and turn it into ISO8601 with ms yourself) or patch nginx to add this.
Interestingly a patch was proposed years ago that would have given enough flexibility to make it possible, but I don't think it went anywhere: http://nginx.2469901.n2.nabble.com/PATCH-time-custom-supports-a-custom-log-timestamp-td3505292.html#none