utah: urlchecker does not check the validity of the preseed location

[Para Siva]

At the moment the url validity checker does not check if the location specified for preseed file is a valid location and that the file exists in where it is said it is.
Since the checker is already doing this check for image files and the run lists, it will be better that it does the same for preseed files.

[Max Brustkern (nuclearbob)]

If we're doing this for preseed files, we might as well do kernel files, initrd files, and vm xml files. There's a block in utah/provisioning/provisioning.py like this:

        for item in ['preseed', 'xml', 'kernel', 'initrd', 'image']:
            if locals()[item] is None:
                self.__dict__[item] = None
            else:
                if '~' in locals()[item]:
                    path = os.path.expanduser(locals()[item])
                    self.logger.debug('Rewriting ~-based path: ' + locals()[item] + ' to: ' + path)
                else:
                    path = locals()[item]
                self.percent = 0
                self.logger.info('Preparing ' + item + ': ' + path)
                self.__dict__[item] = urllib.urlretrieve(path, reporthook=self.dldisplay)[0]
                self.logger.debug(path + ' is locally available as ' + self.__dict__[item])

I think maybe that block, in the base Machine class, would be a good place to insert checking for all of those, since one change there will cover all of those file types. We'd probably want to raise an exception that gets caught by the script provisioning the machine.

[Javier Collado (javier.collado)]

Nice advice. I'll look into checking the URLs in that loop. Thanks.