source: trunk/packages/invirt-base/scripts/invirt-getconf @ 2405

#!/usr/bin/env python

"""
invirt-getconf loads an invirt configuration file (either the original YAML
source or the faster-to-load JSON cache) and prints the configuration option
with the given name (key).  Keys are dot-separated paths into the YAML
configuration tree.  List indexes (0-based) are also treated as path
components.

(Due to this path language, certain restrictions are placed on the keys used in
the YAML configuration; e.g., they cannot contain dots.)

Examples:

  invirt-getconf db.uri
  invirt-getconf hosts.0.ip
"""

from invirt import config
from sys import argv, exit, stderr, stdout
from optparse import OptionParser

class invirt_exception(Exception): pass

def main(argv):
    try:
        parser = OptionParser(usage = '%prog [options] key',
                description = __doc__.strip().split('\n\n')[0])
        parser.add_option('-r', '--refresh',
                action = 'store_true',
                help = 'force the cache to be regenerated')
        parser.add_option('-l', '--ls',
                action = 'store_true',
                help = 'list node\'s children')
        opts, args = parser.parse_args()

        if len(args) > 1:
            raise invirt_exception(__doc__.strip())
        elif args and args[0]:
            components = args[0].split('.')
        else:
            components = []

        conf = config.load(opts.refresh)
        for i, component in enumerate(components):
            progress = '.'.join(components[:i])
            if type(conf) not in (dict, list):
                raise invirt_exception(
                        '%s: node has no children (atomic datum)' % progress)
            if type(conf) == list:
                try: component = int(component)
                except: raise invirt_exception(
                        '%s: node a list; integer path component required, '
                        'but got "%s"' % (progress, component))
            try: conf = conf[component]
            except KeyError: raise invirt_exception(
                    '%s: key "%s" not found' % (progress, component))
            except IndexError: raise invirt_exception(
                    '%s: index %s out of range' % (progress, component))

        if opts.ls:
            if type(conf) not in (dict, list):
                raise invirt_exception(
                        '%s: node has no children (atomic datum)'
                        % '.'.join(components))
            if type(conf) == list:
                for i in xrange(len(conf)):
                    print i
            else:
                for k in conf.iterkeys():
                    print k
        else:
            if type(conf) not in (dict, list):
                print conf
            else:
                import yaml
                yaml.dump(conf, stdout,
                          Dumper=yaml.CSafeDumper, default_flow_style=False)
    except invirt_exception, ex:
        print >> stderr, ex
        return 1

if __name__ == '__main__':
    exit(main(argv))

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