Editing CommunityData:Hyak software installation (section)

==== Installing and making available a custom module ====

{{note}} If you are using <code>screen</code> to run and manage your builds, keep in mind that <code>screen</code> [https://superuser.com/a/235773 drops a few environment variables] such as <code>LD_LIBRARY_PATH</code>, which may mess up your build process. You should check that all the relevant environment variables are set before starting your build. 

The first step toward installing and making available a custom module (in this case, [https://www.jedsoft.org/releases/slang/ slang 2.3.2]) is to spin up the build node, download slang, compile it with a specific prefix, and install it.

<source lang='bash'>
$ build_machine
$ wget https://www.jedsoft.org/releases/slang/slang-2.3.2.tar.bz2
$ tar jxvf slang-2.3.2.tar.bz2
$ cd slang-2.3.2
$ ./configure --prefix=/gscratch/comdata/modules/sw/slang/2.3.2
$ make
$ make install
</source>

The <code>--prefix</code> option to <code>./configure</code> tells the build scripts that slang is going to be installed in <code>/gscratch/comdata/modules/sw/R/3.5.0</code>. This follows a convention that we picked—software in modules should go into <code>/gscratch/comdata/modules/sw/{SOFTWARE_NAME}/{SOFTWARE_VERSION}</code>. The <code>--prefix</code> option is the most important flag for <code>./configure</code>—any other flag or option will be specific to the software being installed.

The second step is to write a <code>modulefile</code>. This contains the metadata about our module. Edit the file <code>/gscratch/comdata/modules/modulefiles/slang/2.3.2</code> to contain the following

<source lang='tcl'>
#%Module1.0####################################################################
##
proc ModulesHelp { } {
        puts stderr "\tModule providing slang 2.3.2"
}

module-whatis "Module providing slang 2.3.2"

prepend-path    PATH            /gscratch/comdata/modules/sw/slang/2.3.2/bin
prepend-path    MANPATH         /gscratch/comdata/modules/sw/slang/2.3.2/share/man
prepend-path    LD_LIBRARY_PATH /gscratch/comdata/modules/sw/slang/2.3.2/lib
prepend-path    PKG_CONFIG_PATH /gscratch/comdata/modules/sw/slang/2.3.2/lib/pkgconfig
</source>

Note that the filename follows a similar convention as <code>--prefix</code> earlier (<code>/gscratch/comdata/modules/modulefiles/{SOFTWARE_NAME}/{SOFTWARE_VERSION}</code>). This file sets up the <code>PATH</code>, <code>MANPATH</code>, <code>LD_LIBRARY_PATH</code>, and <code>PKG_CONFIG_PATH</code>, environment variables appropriately so that the specified version of slang can be accessed and run as needed. There are many more directives that can go into the <code>modulefile</code>—see <code>man modulefile</code> for details on those directives. If your program is a simple binary, you will likely only need to append to the <code>PATH</code>, and <code>MANPATH</code> environment variables.

Once this file is written out, the <code>module avail</code> command should list <code>slang/2.3.2</code> as an available module. This is because the module system is set up to look inside <code>/gscratch/comdata/modules/modulefiles</code> for module files, thanks to the <code>MODULEPATH</code> variable that is set through <code>.bashrc</code>. The command <code>module load slang/2.3.2</code> should make slang available and ready for use. To avoid running <code>module load slang/2.3.2</code> whenever you log in, you can add the command at the end of your <code>.bashrc</code> file (after the section that sets <code>MODULEPATH</code>).