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There are at least 3 log-generating things you'll be concerned with:
- The app server (Jira, Confluence), and their its log files (atlassian-jira.log, atlassian-confluence.log)
- The web server (Apache, nginx) and their its log files (access.log, error.log)
- The operating system and its logs (/var/log/*) and persistent performance stats (e.g. /var/log/atop/*)
Events across these often need to be correlated - for instance, a spike in requests (access.log) triggers high server load (operating system), and eventually application errors (atlassian-jira.log). For your debugging sanity, it is essential that all these log files must have the same timezone.
The web server and OS logs are all in the OS timezone, obviously. How about app server logs, atlassian-jira.log and atlassian-confluence.log?
App server log timestamps will also be in the OS timezone, unless you've told Java otherwise by explicitly setting -Duser.timezone . If To spell it out: if you've set -Duser.timezone , you can no longer correlate datestamps between atlassian-jira.log, access.log and the rest of the system.
So don't do that. Don't ever set -Duser.timezone. Leave Java in the same timezone as your OS.
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I work on Linux, and my tooling hasn't evolved much since the 1970s. I don't know an easy way to convert log timestamps from UTC to that of an arbitrary usersomething else, on the fly. If the log's timezone is that of the user, life just is just easier.
The argument from Confluence developer laziness
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So in Jira, everything is great. You can have atlassian-jira.log use a timezone that's good for debugging (UTC if that's your preference), while the default timezone used to render dates can be something good appropriate for the majority of users.
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