GLExec Environment Wrap and Unwrap scripts

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GLExec Wrap and Unwrap environment variables describes how you can wrap environment variables (from a Pilot Job Framework) in such a way that they don't get wipe and unwrap them (safely) in the target account (Pilot Job Payload) process.

Where to find packages and sources

We provide a new packages named glexec-wrapper-scripts (at the moment primarily) through the Etics system.

The sources can be found in our SVN repository.

gLExec wrapper scripts: glexec_wrapenv.pl and glexec_unwrapenv.pl

Helper scripts to restore the environment variables previously wrapped into the environment variable GLEXEC_ENV using the glexec_wrapenv.pl script.

Intended usage of glexec_wrap.pl and glexec_unwrap.pl

export GLEXEC_ENV=`glexec_wrapenv.pl`
/opt/glite/sbin/glexec glexec_unwrapenv.pl -- <YOUR-COMMAND>

(Making) Exceptions

By default the following environment variables are NOT unwrapped:

  • HOME
  • LOGNAME
  • USER
  • X509_USER_PROXY
  • _ (yes that's '_' !)

This set of environment variables must kept relative to the active user account. The X509_USER_PROXY and the HOME variables are set explicitly to values that are appropriate to the mapped user account.

A user can add more env vars to be excluded using either 

--exclude=A --exclude=B

or 

--exclude=A,B,...

Examples

Example 1: 

export GLEXEC_ENV=`glexec_wrapenv.pl --exclude=MYVAR`
/opt/glite/sbin/glexec glexec_unwrapenv.pl -- <YOUR-COMMAND>

Example 2: 

export GLEXEC_ENV=`glexec_wrapenv.pl`
/opt/glite/sbin/glexec glexec_unwrapenv.pl --exclude=MYVAR -- <YOUR-COMMAND>

Example 3: 

export GLEXEC_ENV=`glexec_wrapenv.pl --exclude=MYVAR`
/opt/glite/sbin/glexec glexec_unwrapenv.pl -- <YOUR-COMMAND>

Combined, easy to adopt, script

We've combined the two Perl scripts and the gLExec call into a plain and simple shell script. This script is also packaged in the glexec-wrapper-scripts as the shell script: /opt/glite/sbin/glexec_wrap.sh

Content: 

#!/bin/sh
cd ${GLITE_LOCATION:-/opt/glite}
export GLEXEC_ENV=`${0%/*}/glexec_wrapenv.pl`
exec ${GLITE_LOCATION:-/opt/glite}/sbin/glexec ${0%/*}/glexec_unwrapenv.pl -- $@

Usage: 

/opt/glite/sbin/glexec_wrap.sh /usr/bin/id -a
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