Where is the JRE?

[Jeff Dege]

We have Jenkins 1.561 running on a 64-bit Windows 7 Professional SP1 box.

This is our primary build machine, it runs Jenkins as well as most of our actual builds.  (Our load isn't sufficient to require a more complicated multi-server structure).

Now my understanding is that Jenkins is written in Java, and relies on the JRE.

We've recently started Android development, which means I need to install Android Studio/gradle/et al. on the build machine. Which is also the machine on which Jenkins runs.

Android Studio is also written in Java, and needs the JDK installed. Now it's perfectly possible to have two different versions of Java installed on the same machine, without conflict. But it's also possible for a new installation to mess up programs that rely on the old, without realizing it.

So I'm trying to track down just what are the Java dependencies within our existing Jenkins installation.  And I'm not having much luck.

I don't see any version of Java in the Windows Control Panel's list of installed programs ("Programs and Features").

Browsing around the web, I've seen references to a jenkins.xml file, that was supposed to be sitting in $JENKINS_HOME, that had a default setting pointing to $JENKINS_HOME/jre.  But I don't see any such file in $JENKINS_HOME, and I don't see a jre directory, in $JENKINS_HOME or anywhere else.

When I go into Manage Jenkins => Configure System, I see a section "JDK Installations", but there are none configured.

Are these configuration settings and defaults different, on Windows, have they moved?

Where is the JRE that my install of Jenkins is depending on? And where is the configuration setting that creates that dependency?

[Suckow, Thomas J]

Manage Jenkins -> System Information 

should include the path to the Java Install being used. It is probably listed in the java.home environmental variable.

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[Jeff Dege]

OK, never mind.

People are assuming that JAVA_HOME is also where the Jenkins application is installed.  That may be the default, but it makes no sense to me, and we changed it long ago.

I found jenkins.xml in the Jenkins installed directory, and the jre alongside it.

Now that I know where is the JRE that Jenkins is using, I can make sure that the new JDK7 doesn't mess with it,

On Friday, May 1, 2015 at 12:31:50 PM UTC-5, Jeff Dege wrote:

Browsing around the web, I've seen references to a jenkins.xml file, that was supposed to be sitting in $JENKINS_HOME, that had a default setting pointing to $JENKINS_HOME/jre.  But I don't see any such file in $JENKINS_HOME, and I don't see a jre directory, in $JENKINS_HOME or anywhere else.