Fwd: [DISCUSS] Change Jenkins default logging format

Baptiste Mathus

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Apr 12, 2018, 3:41:18 AM4/12/18

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Hello everyone,

I am transferring this email I originally posted in the dev list a few days ago to gather more feedback.

To sum up: I am proposing to change the current logging format to a more consise and machine-friendly one-liner (when there's no stacktrace)

If you wish to see it changed, or not, please comment on the subject detailed below.

Thanks!

---------- Forwarded message ----------
From: Baptiste Mathus <m...@batmat.net>
Date: 2018-04-04 15:17 GMT+02:00
Subject: [DISCUSS] Change Jenkins default logging format
To: Jenkins Developers <jenkin...@googlegroups.com>

Hello everyone,

Having worked on more things related to Jenkins logging recently, I've had the opportunity to remember my past pain when I was operating a Jenkins instance and sending logs to an ELK cluster.

Compared to almost everything else in the infrastructure, the logstash rules for Jenkins logs were unnecessarily complex.

The main pain-points, for me at least, had been the two-lines (sigh) per log default, and also the localized date format (or log level...).

Even now, so many years after reading those, I still struggle daily to make sure I'm reading the right line/date associated to the message I'm reading on the line above.

I would like to propose we change the current logging format behavior to a more readable and more operation-friendly one.

This would result in something close to the following format:

[ INFO][2018-04-04 12:40:49] Logging initialized @180ms to org.eclipse.jetty.util.log.JavaUtilLog (from org.eclipse.jetty.util.log.Log initialized)

[ INFO][2018-04-04 12:40:49] Beginning extraction from war file (from winstone.Logger logInternal)

[WARNING][2018-04-04 12:40:49] Empty contextPath (from org.eclipse.jetty.server.handler.ContextHandler setContextPath)

[ INFO][2018-04-04 12:40:49] jetty-9.4.z-SNAPSHOT (from org.eclipse.jetty.server.Server doStart)

Instead of the usual:

Apr 04, 2018 12:36:41 PM org.eclipse.jetty.util.log.Log initialized

INFO: Logging initialized @354ms to org.eclipse.jetty.util.log.JavaUtilLog

Apr 04, 2018 12:36:41 PM winstone.Logger logInternal

INFO: Beginning extraction from war file

Apr 04, 2018 12:36:42 PM org.eclipse.jetty.server.handler.ContextHandler setContextPath

WARNING: Empty contextPath

Apr 04, 2018 12:36:42 PM org.eclipse.jetty.server.Server doStart

INFO: jetty-9.4.z-SNAPSHOT

WDYT?

If this looks interesting to people, I'm ready to file the associated JEP for it and possibly work on its implementation in the future.

Obviously, we would need some way to revert to the "legacy" format, at least for some time for users to adapt. But that is not something I'm particularly worried about.

-- Baptiste

Reinhold Füreder

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Apr 12, 2018, 4:06:06 AM4/12/18

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Hi Baptiste,

Definitely +1! That is I wish to see the default logging format changed to a one-liner.

This is more or less what in our Ansible based provisioning of Jenkins setup is already done:

# See http://stackoverflow.com/questions/194765/how-do-i-get-java-logging-output-to-appear-on-a-single-line

- name: setup | Configure log output format

lineinfile: dest=/etc/default/jenkins

insertafter='^JAVA_ARGS=.*'

regexp='^JAVA_ARGS.*java.util.logging.*'

line="JAVA_ARGS=\"$JAVA_ARGS -Djava.util.logging.SimpleFormatter.format='%1\$tY-%1\$tm-%1\$td %1\$tH:%1\$tM:%1\$tS %4\$4s [%2\$s] %5\$s%6\$s%n'\""

Regards,

Reinhold

Osborn, Tammy (DNR)

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Apr 12, 2018, 9:21:54 AM4/12/18

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This sounds like a great idea to me. I haven’t had to deal with the logs much but simpler is better when there’s no stack trace like Baptiste suggested.

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Baptiste Mathus

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Apr 12, 2018, 10:28:28 AM4/12/18

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Sorry, I was unclear. There *will* still be stack traces IMO, they are critical to understand what is happening.

I meant: the logs will typically be one-line.

But when a given log entry has an associated exception, then it will be printed mostly like now, i.e. with a variable number of lines.

Joining lines when there are exceptions with log-analysis tools like logstash is mostly trivial, you typically detect "at ...", etc. and tell it that it goes with the previous log line.

Note that I guess we _could_ consider making the stacktraces possible to disable, but I think this is a bad idea.

When something goes wrong, this is the first thing typically, for instance on this mailing list, that we would ask reporters to re-enable and come back when the issue has reoccurred with (or in JIRA reports).

Cheers

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Osborn, Tammy (DNR)

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Apr 12, 2018, 11:36:58 AM4/12/18

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I agree. My reply wasn’t well worded. I’d like to have the complete stacktraces included but when it’s just a routine message, have 1 liner.

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niristotle okram

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Apr 12, 2018, 12:03:33 PM4/12/18

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Definitely yes.

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