cfmteset CLI module first pass

cli.py

import os
import sys
import optparse
import cfmtest.build
#import cfmtest.test
#import cfmtest.destroy

CFMTEST_COMMANDS = [ "build" ] #, "test", "destroy" ]

class CLI:
    """
    Implement CLI parsing for cfmtest.
    """

    def __init__(self):
        self.parser   = optparse.OptionParser(
            description = "a configuration management LXC test harness"
        )

    def get_command(self, args):
        """
        Get the subcommand before parsing all options.
        """
        if len(args) < 2:
            print >> sys.stderr, "At least one argument is required - (build|test|destroy)."
            sys.exit(1)
        elif args[1] in CFMTEST_COMMANDS:
            return args.pop(1)

        print >> sys.stderr, "Invalid command, '%s'.  Use one of (build|test|destroy)." % args[1]
        sys.exit(1)

    def check(self):
        """
        Make sure privileges & environment are sufficient to run.
        """
        if os.geteuid() != 0:
            print >> sys.stderr, "These tools must run as root for now."
            sys.exit(1)


    def run(self, args):
        """
        Process the command line.
        """
        # pull the command from the arguments before calling into optparse
        cmd = self.get_command(args)

        # optparse
        self.parser.add_option("--build-id", dest="build_id",
            help="CI Tool build ID, e.g. Hudson/Jenkin's BUILD_ID environment variable")
        self.parser.add_option("--root-subvol", dest="root_subvol",
            help="a BTRFS subvolume containing an OS filesystem root to use for testing")

        if cmd is "build":
            self.parser.add_option("--workspace", dest="workspace",
                help="Path to a checked out copy of the CFM policy.")

        opts, leftover = self.parser.parse_args(args)
        options = vars(opts)

        # for some weird reason, optparse doesn't have require switch
        if options["build_id"] is None:
            self.parser.error("--build-id is a required option")
        if options["root_subvol"] is None:
            self.parser.error("--root-subvol is a required option")

        # each command has its own class and they're already loaded, so
        # instantiate the object and call its run()
        #
        # convert the command string to a module object
        cmd_module = sys.modules["cfmtest.%s" % cmd]
        # now get the object for the class
        cmd_class = getattr(cmd_module, cmd.capitalize())
        # instantiate an object using CLI args
        cmd_object = cmd_class(**options)
        # call the run method
        return cmd_object.run()