Question: I am a newbie to Chef.

We are upgrading JDK on all of our servers including CHEF servers also.

I found JDK version (1.6) installed on the chef servers. But I am not sure if it is being used by the Chef servers. OR, Does Chef servers uses its own java.

Thanks in advance

Answer: 
Yes, Chef Server uses Apache Solr as search index ([reference](https://docs.chef.io/server_components.html)). Solr is a Java software.

Usually, Chef Server is installed using the Omnibus installer, which brings all of its dependencies (and installs them to `/opt/opscode`). The JRE shipped by Chef Server is located under `/opt/opscode/embedded/jre`.

Thus, Chef Server ignores the JDK installed by the operating system.
To the best of my knowledge, Chef Server does not use Java for any of its core components. The Chef [documentation for server system requirements](https://docs.chef.io/chef_system_requirements.html) does not list Java as a requirement, and running [CLOC](http://cloc.sourceforge.net/) on the Chef source code does not turn up any Java source code files.

*However*, it is possible that your Chef environment is making use of some Java tool or utility that is not part of Chef itself, but that one of your Chef scripts depends on. So proceed with caution. You might want to poke around a bit to see if any processes are using java with a command such as `jps -lV` (lists pid and main class) or `ps aux | grep java`. Of course, that will only show currently running processes. If you know who setup and administered the server, it would be worth asking them if any core component relies on Java.

Lastly, you can upgrade Java by installing another version, which will leave the currently installed version in place, so reverting the default version is usually trivial if something does break after upgrade.