sidai-vwrapper (was Re: development/staging/production)

Hi,

Just thought I'd let you know about my "vwrapper" (version wrapper)
stuff that I checked in a few weeks ago, but forgot to announce on the
mailing list.

It's kind of related to Harlan's development/staging/production point in
that it allows a number of different versions of a particular tool to
coexist on the system and allows different users to use different versions
transparently. This is handy for a number of situations:

* testing new versions of software before making them generally available
* to use freeze a project by insisting on a particular version of a tool,
to prevent the tool changing "under your feet" when it comes to release
time.

So for instance, with coreBulder (from Synopsys' SRT hardware design
package), you can do:

sli4523:/home/mholgate: coreBuilder --show-versions
Versions of coreBuilder available:
  2000_10_25
  2001_01_30

and

sli4523:/home/mholgate: coreBuilder --use-version=2000_10_25

and the correct version will be invoked. It can be conceived that this
would be used in a Makefile to ensure that every developer in a project
uses the same set of tools.

In addition, you can have a ~/.wrapperrc file which specifies default
versions of packages to use, which is more use when manually invoking
tools:

synopsys-srt=2000_10_25
gcc=2.95.2
textutils=4.0z

There is also an equivalent site wide file.

Vwrapper it takes advantage of the fact that the Sidai Way of handling
packages is to have a deployment directory with a name containing the
version of the package eg:

/.-ark-deploy/synopsys-srt--2000_10_25
/.-ark-deploy/synopsys-srt--2001_01_30

It generates a wrapper for each executable which simply invokes the
correct version of the real tool.

The actual code for the wrapper is in the sidai-vwrapper package, while
the ark-vwrapped proto-package is used for packages that wish to use the
wrapper. So for gnu ls (a silly example!), you might have the following
packages:

fileutils--4.0z
fileutils--4.1

which are standard ARK packages, but are only deployed and not revealed.

You would also have a

fileutils-wrapper

package, which would have ark-vwrapper as a prototype and would simply
generate a wrapper script for all the binaries in fileutils (including
ls). (See below). These would be revealed in place of the real binary.

So you would have:

/our/bin/gls (wrapper script from fileutils-wrapper package)

and

/.-ark-deploy/fileutils--4.0z/bin/gls
/.-ark-deploy/fileutils--4.1/bin/gls

(real binaries from the fileutils--4.0z and fileutils--4.1 packages).

I know this explained badly, but I'm about to fall asleep at the
keyboard, so I'm making no sense whatsoever please let me know ;-)

Matt






#!/usr/bin/env python

# Autogenerated Sidai-style version wrapper for:
#   bin/gls
# in package:
#   fileutils
#

import sys
sys.path.append("/our/lib/sidai-vwrapper")
import wrapper

SYSADMIN = "[email protected]"
DEPLOY_DIR = "/.-ark-deploy"
GLOBAL_CONF = "/our/lib/sidai-vwrapper/default-fileutils"
USER_CONF = "~/.wrapperrc"
EXECUTABLE = "bin/ls"
PACKAGE = "fileutils"

try:
    wrapper.wrap( sys.argv, EXECUTABLE, PACKAGE,
                  DEPLOY_DIR, GLOBAL_CONF, USER_CONF )

except wrapper.ExitSuccess, e:
    sys.exit( 0 )

except wrapper.ExitFailure, e:
    sys.stderr.write( '[wrapper]  %s\n' % e )
    sys.stderr.write( 'If you did not expect this error, please contact '
+
                      SYSADMIN + '.\n' )
    sys.exit( 99 )