# Runtime Environments

This page contains notes about using various runtime environments inside Isolate 
sandboxes.

## Python

Due to a [Python bug](http://bugs.python.org/issue10496), the interpreter 
requires the `$HOME` variable to be set to something. Otherwise, it tries to 
look up the UID used by Isolate in `/etc/passwd` and fails. Setting `HOME=/box` 
seems to work.

## Java

By default, we use a Groovy script that looks for a class with a `main` method and executes it for running Java programs. For this setup to work correctly, we need to set the `JAVA_HOME` environment variable and make sure that `$JAVA_HOME/jre/lib/amd64/jvm.cfg` is accessible from the isolate sandbox. The file can be a link to a file in a folder in `/etc`, which also needs to be bound to the sandbox (it is not recommended to bind the whole `/etc/` folder into the sandbox).

Also, some versions of `/usr/bin/groovy` use `ls` - make sure that it is accessible from the sandbox.