Transition_to_Lmod7.txt

I am very pleased to announce that Lmod Version 7 is ready for
testing.  The user interface to Lmod remains the same but the
internals to Lmod have been refactored yet again. So I'm releasing
this for testing.

It is available from github on branch nvv.  Currently, this branch has
a version 6.9.*-beta.  Once testing is complete this will become Lmod 7+.

I am asking for volunteers to test this so that important new
features can be made available to sites.  Many sites want to hide
modules without removing them.  If your sites never removes modules
but wants to discourage new users from using old modules then
this feature.  In the MODULERC file you can now do:

     #%Module
     hide-version     mpich/3.2-dbg
     module-version   gcc/4.8.1       default

You can hide a module by specifying its full name.  You can also set a
default module.  The ability to hide modules is new.  The ability to
specify a default here is new to Lmod but has been supported by Tmod
for a long time.

Your site can use the standard location of the RC file.  If you
install Lmod in:

    /apps/lmod/<lmod-version>/

then the MODULERC file is

   /apps/lmod/etc/rc

You can check what Lmod thinks the location is by checking
"module --config". Or you can define the environment variable MODULERC
to point a file of your choice.

Users can also specify a personal ~/.modulerc file.  The rules are
that a users ~/.modulerc file has priority over the system MODULERC
file which has priority over a .modulerc file stored with the
modulefiles. 


Testing Lmod 7:
---------------

I am recommending that you test this in your personal accounts as
discussed in:

   https://lmod.readthedocs.io/en/latest/045_transition.html

There are three issues to be aware of:

First: $LMOD_DEFAULT_MODULEPATH is not used anymore.  Lmod no longer
needs to track "Core" modulefile directories versus Compiler or
Compiler/MPI dependent modulefile directories.

Second: The name and contents of the spider cache file have changed.
The previous name was moduleT.lua.  The new name is spiderT.lua.  The
"update_lmod_system_cache_files" has been updated to generate the new
name and contents.  If you use your own script to call the "spider"
command please change it to:

   $ spider -o spiderT $MODULEPATH > /path/to/lmod/cacheDir/spider.

Third: The format for the collection file has changed.  Lmod 7 will read
old collection files.  However if a user creates a new collection
file, Lmod 6 will not be able to read it.  This should only be a
problem when testing.