Singularity installation on GPFS

[Jonathan Casco]

Hello,

I have been reading through the Singularity documentation planning to compile from source and load via Module. From reading the documentation and some of the past posts on this list I had a some questions.

In the documentation I came across this for the --localstatedir option (http://singularity.lbl.gov/admin-guide#prefix-in-special-places-localstatedir):

You may also experience issues if this directory is shared between several hosts/nodes that might run Singularity simultaneously.

From this it seems like my idea of using Singularity and Modules would not be a proper implementation. I have read other posts where this is referring to NFS shares so would this warning be applicable to installation on GPFS mounts as well?

The documentation also prefers that Singularity is installed directly on the hosts via RPM. Is loading Singularity via Module something to be avoided?

Otherwise any tips or things I should consider would also be appreciated.

Thanks!

[David Godlove]

Hi Jonathan, 

Although many sites do install from source on NFS and then use modules to manage, this is not the recommended approach.  In addition to the issue with the localstatedir that you point out, there is also a philosophical issue with supporting multiple versions of Singularity:

Singularity is not a "normal scientific app".  Parts of the code path run with elevated privs via a setuid bit.  New versions of Singularity often contain security patches.  If you support legacy Singularity versions you must pay close attention to which version are safe and which version are not or else you may be asking for trouble.  It's usually best to only support the latest version of Singularity.  

These are some of the issues that Sylabs aims to solve with Singularity Pro.  It's analogous to running Fedora vs RHEL.  Basically, Sylabs has created supported snapshots of the Singularity open source software that will be supported for the long term with backported bug fixes and security patches.  

Dave

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[Jonathan Casco]

Hi David,

Could you go over the issues that Singularity runs into when using a shared mount? This would be something likely used with both the community and Pro versions were we to go forward with an installation.

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[David Godlove]

Hi Jonathon,

The biggest issue with installing to NFS is the localstatedir that you already pointed out.  As long as you make that local and create it on each node I think you should be OK.  Greg has pointed out some other reasons to prefer installing via RPM over building from source.  They mostly boil down to having the ability to track, audit, and prescriptively define specifics about your installation.  

Dave

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