Jenkins 1.6XX master with old Linux (Red Hat 4) slaves

[Carl Wilson]

I've got a new Jenkins master (1.622) running on CentOS 6.6 x86_64, tomcat 8, java 1.8.  All working ok.

I've just had a request for a build on an old Linux slave - Red Hat 4 with Java 1.6 (32 bit).  Yes, I know it's obsolete, and it ought to be upgraded to plug all the security holes - but that's what I need.

Normally we connect to Linux slaves via ssh, however I know that these are basically incompatible.  slave.jar needs jdk 1.7, at least and that won't run properly on Red Hat 4 because of glibc library.  However it WILL connect using JNLP whilst launching the interactive java Jenkins Remoting Agent, but NOT whilst running the jnlp command line command from the slave.

I can understand why the command line launch doesn't work with the java version incompatibilities.

An old version of slave.jar from an old Jenkins master seems to work ok, and may be 'good-enough', but how robust is it?  Are there any listings of version compatibilities?

Does anyone have any ideas on how to get an old Linux machine enslaved to a new Jenkins master?  Any alternative connection techniques?

I guess the obvious solution is just to use an old Jenkins master which is compatible…

[Stephen Connolly]

1.622 is the other side of the Java 7 switch.

As a result there are classes in core that have been compiled with Java 7 bytecode and references to methods / classes that are only available in Java 7.

While you can get the remoting connection up - as that does not rely on classes from Jenkins itself - running a build will be a different problem entirely.

You probably need to switch back to 1.609 LTS as that is the last LTS that is compiled against Java 1.6.

You will also need to be careful with the plugins that you use. Plugins can send code to the remote slaves. If they try to send some Java 1.7 code to your slaves running 1.6... boom!

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