wreck/lua.d: add openmpi.lua

Add an "MPI personality" for OpenMPI that sets LD_LIBRARY_PATH
to find Flux libpmi2.so.

src/modules/wreck/Makefile.am

@@ -66,7 +66,8 @@ dist_wreckscripts_SCRIPTS = \
         lua.d/input.lua \
 	lua.d/mvapich.lua \
 	lua.d/pmi-mapping.lua \
-	lua.d/intel_mpi.lua
+	lua.d/intel_mpi.lua \
+	lua.d/open_mpi.lua
 
 # XXX: Hack below to force rebuild of unbuilt wrexecd dependencies
 #

src/modules/wreck/lua.d/openmpi.lua

@@ -0,0 +1,31 @@
+-- Set environment specific to openmpi
+--
+-- If configured for SLURM, OpenMPI links with libpmi.so or libpmi2.so
+-- (depending on options used).  Flux provides alternate versions of these
+-- libraries in a non-default location, and we must set LD_LIBRARY_PATH to
+-- point there.
+--
+-- Some versions of OpenMPI, 1.10.2 for example, set an rpath for their
+-- PMI plugins that includes /usr/lib64.  That is bug and those versions
+-- need to be patched patched to work with Flux.
+-- 
+-- If Flux supports the PMI-2 wire protocol, the SLURM libpmi.so might
+-- work with Flux.  It currently doesn't, and in fact ignores the protocol
+-- version handshake entirely.   (See flux-framework/flux-core#746)
+
+
+local dirname = require 'flux.posix'.dirname
+
+function rexecd_init ()
+    local env = wreck.environ
+    local f = wreck.flux
+    local libpmi = f:getattr ('conf.pmi_library_path')
+    local ldpath = dirname (libpmi)
+
+    if (env['LD_LIBRARY_PATH'] ~= nil) then
+        ldpath = ldpath..':'..env['LD_LIBRARY_PATH']
+    end
+    env['LD_LIBRARY_PATH'] = ldpath
+end
+
+-- vi: ts=4 sw=4 expandtab