[[!meta title="Managing custom software with environment modules in the Systems Group"]]

## The problem

Maintaining custom software as a sysadmin is not easily possible for
a research group, because ressources needed to do so easily exceed
the available working time, as soon as the number of software 
installations is getting too big or the software too complex.

Researchers on the other hand rely on up-to-date or unpackaged
software to do their work.

## General solution

One way to solve this issue is to provide a way researchers can install
and maintain their own software, without interferring with the system
software.

## Software solution

One possible software solution is provided by the
[Environment Modules Project](http://modules.sourceforge.net/).

## Implementation

The path **/pub/env-modules** should contain the user maintained
software and is mounted via **nfs** and **autofs**.
The Environment Modules Package is installed below
**/pub/env-modules/Modules**, the files to configure modules
(**modulefiles**) reside below **/pub/env-modules/modulefiles/**.

### Installation of modules

The usual three step work fine, if you've tcl installed:

    modules-3.2.8% ./configure --prefix=/pub/env-modules --with-module-path=/pub/env-modules/modulefiles
    modules-3.2.8% make
    modules-3.2.8% make install

## Usage

### Creating a new module (sysadmin part)

Create a new directory below **/pub/env-modules** and a link
below **/pub/env-modules/modulefiles/** to the newly created directory.
Now give ownership to the researcher who is maintaining the new software,
who can install the software and create a specific modulefile for the
software. For instance:

    % mkdir /pub/env-modules/cdist
    % chown nicosc /pub/env-modules/cdist
    
    # Delegate support for cdist maintenance into the user owned folder
    % ln -s /pub/env-modules/cdist/modulefiles /pub/env-modules/modulefiles/cdist

### Creating a new module (user part)

Install the software into your directory and create modulefiles below the
modulefiles directory:

    % git clone git://git.schottelius.org/cdist /pub/env-modules/cdist/
    % mkdir /pub/env-modules/cdist/modulefiles
    % cat << eof > /pub/env-modules/cdist/modulefiles/git
    #%Module1.0#####################################################################
    ##
    ## cdist modulefile
    ##
    ## 
    ##
    proc ModulesHelp { } {
       puts stderr "\tLet's you use cdist"
    }
    
    module-whatis  "Configuration Management"
    
    append-path PATH  /pub/env-modules/cdist/bin
    eof

### Using env modules

To actually make use of the new modules, you need to add env modules into your
shell. The following commands illustrate the way for the **bash**:

    % . /pub/env-modules/Modules/3.2.8/init/bash
    % module avail
    
    ----------------------------------- /pub/env-modules/Modules/versions -----------------------------------
    3.2.8
    
    ------------------------------------- /pub/env-modules/modulefiles --------------------------------------
    cdist/git
    % module load cdist/git
    % module list
    Currently Loaded Modulefiles:
      1) cdist/git



[[!tag config eth unix]]