[Reproduce-devel] [task #15361] mpi FAQ - openmpi refuses to run as root

[Boud Roukema]

URL:
  <https://savannah.nongnu.org/task/?15361>

                 Summary: mpi FAQ - openmpi refuses to run as root
                 Project: Reproducible paper template
            Submitted by: boud
            Submitted on: Wed 07 Aug 2019 09:40:18 PM UTC
         Should Start On: Wed 07 Aug 2019 12:00:00 AM UTC
   Should be Finished on: Wed 07 Aug 2019 12:00:00 AM UTC
                Category: None
                Priority: 1 - Later
                  Status: None
                 Privacy: Public
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                  Effort: 0.00

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Details:

Quoting https://www.open-mpi.org/doc/v2.0/man1/mpirun.1.php#sect22

> The Open MPI team strongly advises against executing mpirun as the root
user. MPI applications should be run as regular (non-root) users.
> 
> Reflecting this advice, mpirun will refuse to run as root by default. To
override this default, you can add the --allow-run-as-root option to the
mpirun command line. 

Apparently mpich allows the user to run as root without complaining - which is
an example of why openmpi is probably a more thorough community developed
implementation. There are other mpi implementations too - I've no idea how
many others are as careful as openmpi.

When we start preparing documentation, we could add a comment for those users
who do everything as root ("noone else but me uses my computer") or those who
do things in a chroot gaol. I didn't quite see where package-specific
documentation would make sense, so I'm posting this here so it doesn't get
forgotten.

However, I'm not fully sure about this being worth documenting - if we try
documenting every possible mistake, including those easily found by
duckduckgoing <https://duckduckgo.com> or qwanting <https://qwant.com>, then
we'll be wasting time doing what other groups/networks already do better.
People should look for info in the place they expect (and preferably without
totalitarian search engines). E.g. we're not going to distribute tutorials in
C or fortran or shell.

Comment: In preparing Debian binary executables, chroot is normally used,
since the idea is to simulate a root user installing libraries and so on. So
--allow-run-as-root is enabled during after building the mpgrafic binary, so
that a minimal reproducible "science run" can be tested. (An alternative could
be to create a dummy user, run user-level tests, and then rm the dummy user.)





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