Motivation and intended usage:

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To get an RStudio Server in the kubernetes cluster, you go to https://kubeportal.cc.lehigh.edu, then click on the "Class Apps" dropdown menu along the top of the page and selects "RStudio server (kubernetes)" for the generic RStudio instance in kubernetes, or the particular application for their your course if applicable (a course can get its own entry here if it maps a network shared drive that is specific to the course).  You are brought to a form where you can select the version of R that you want, and then you can click the "Launch" button.  It takes a minute or so two for the instance to start, and then a "Connect to RStudio Server" button appears that takes you to your RStudio instance.

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Your home directory that's mounted inside your JupyterLab or RStudio Server instance is actually stored on a remote NFS server, so any files the you create or modify will persist after your session ends.  The next time you log in, the same files will still be there.  The home directory used by JupyterLab is different from RStudio Server though - you won't see the same files in both. 

These home directories are generally archived at the end of each semester, so the data in them does go away eventually - don't leave anything important in them.

Session management:

You can get back to a running JupyterLab session by just going back to jupyter.cc.lehigh.edu and logging in again.  For as long as it is still running, your RStudio Server is available at https://rstudio.cc.lehigh.edu/<your username>/.  You can also get to it by going back to https://kubeportal.cc.lehigh.edu/ and clicking on the "My Interactive Sessions" link along the top menu bar.

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The following error in RStudio is harmless:

2022-01-26T20:04:48.938685Z [rsession-<username>] WARNING No memory control group found in /proc/self/cgroup; LOGGED FROM: std::__cxx11::string rstudio::core::system::{anonymous}::getMemoryCgroup() src/cpp/core/system/LinuxResources.cpp:335

It shows up on starting an RStudio Server session.  We have not yet found a way to prevent it from happening.  The error is related to a version mismatch between kubernetes, the container engine it's using to run RStudio, and the OS running both.  It should eventually go away when we are able to upgrade everything to use the same version of "cgroups", which are used to control the resources granted to containers.  Everything will still work fine in spite of this error.

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Upon using the "plot" function in RStudio, this error may appear:

Warning message:
In grSoftVersion() :
  unable to load shared object '/usr/local/lib/R/modules//R_X11.so':
  libXt.so.6: cannot open shared object file: No such file or directory

This is also harmless - the plot function still works.  The error is caused by the way the container was built - the RStudio images are based on the Rocker project (https://www.rocker-project.org/ ) and this is related to the way they built the image.  An update to the image would fix it - we'll raise an issue in the Rocker project's github to make sure they are aware of it.

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