To upgrade from earlier versions of Jenkins, simply redeploy the WAR file. Read this document for more about container-specific instructions on how to do this. See this document for automation.
Programming Language specific topics
Running Jenkins as a daemon
Most of the art work is derived from Tango Project, and thus this portion of Jenkins is covered by their license (Creative Commons Attribution Share-Alike license). The rest (that is, all the code, documents, build scripts, etc.) is covered by the MIT license, unless otherwise stated in individual files.
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