Synnefo

#!/usr/bin/env python

#

# Copyright (c) 2010 Greek Research and Technology Network

#

"""Ganeti hook for Synnefo

This is the generic Synnefo Ganeti hook.

It uses the full path of the hook, as passed through sys.argv[0]

to discover the root of the Synnefo project, then passes

control to the function which implements this specific hook,

based on the GANETI_HOOKS_PATH and GANETI_HOOKS_PHASE env variables,

set by Ganeti.

"""

import logging

from django.core.management import setup_environ

import sys

import os

# Discover the path for the Synnefo project.

#

# IMPORTANT:

# This assumes this script has been *linked* into the /etc/ganeti/hooks

# directory on the master and nodes, and that it lives in a ganeti/ directory

# under the Synnefo project root.

try:

    target = os.readlink(sys.argv[0])

except OSError:

    target = sys.argv[0]

target_script = os.path.abspath(target)

target_dirname = os.path.dirname(target_script)

if os.path.split(target_dirname)[1] != "ganeti":

    raise Exception, "Unexpected location for the Synnefo Ganeti hook, " \

        "cannot determine Synnefo project root.\n" \

        "This script run as: %s\nLocation determined to be at: %s\n" \

        "Script in %s, not under ganeti/ directory." % \

        (sys.argv[0], target_script, target_dirname)

# Add the parent of the project root to sys.path (for Python imports),

# then load Django settings.

# FIXME: Why do import references start at synnefo.* ?

synnefo_project_root = os.path.split(target_dirname)[0]

sys.path.append(os.path.join(synnefo_project_root, '..'))

import synnefo.settings as settings

setup_environ(settings)

# A hook runs either in the "pre" or "post" phase of a Ganeti operation.

# Possible values for the Ganeti operation are "instance-start",

# "instance-stop", "instance-reboot", "instance-modify". See the Ganeti

# documentation for a full list.

# The operation and phase for which the hook run are determined from the 

# values of the GANETI_HOOK_PATH and GANETI_HOOK_PHASE environment variables.

# For each valid (operation, phase) pair control passes to the corresponding

# Python function, based on the following dictionary.

from synnefo.ganeti.hooks import \

    PostStartHook, PostStopHook

hooks = {

    ("instance-add", "post"): PostStartHook,

    ("instance-start", "post"): PostStartHook,

    ("instance-reboot", "post"): PostStartHook,

    ("instance-stop", "post"): PostStopHook,

    ("instance-modify", "post"): PostStartHook

}

def main():

    logging.basicConfig(level=logging.DEBUG)

    logger = logging.getLogger("synnefo.ganeti")

    try:

        instance = os.environ['GANETI_INSTANCE_NAME']

        op = os.environ['GANETI_HOOKS_PATH']

        phase = os.environ['GANETI_HOOKS_PHASE']

    except KeyError:

        raise Exception("Environment missing one of: " \

            "GANETI_INSTANCE_NAME, GANETI_HOOKS_PATH, GANETI_HOOKS_PHASE")

    prefix = instance.split('-')[0]

    # FIXME: The hooks should only run for Synnefo instances.

    # Uncomment the following lines for a shared Ganeti deployment.

    # Currently, the following code is commented out because multiple

    # backend prefixes are used in the same Ganeti installation during development.

    #if not instance.startswith(settings.BACKEND_PREFIX_ID):

    #    logger.warning("Ignoring non-Synnefo instance %s", instance)

    #    return 0

    try:

        hook = hooks[(op, phase)](logger, os.environ, instance, prefix)

    except KeyError:

        raise Exception("No hook found for operation = '%s', phase = '%s'" % (op, phase))

    return hook.run()

if __name__ == "__main__":

    sys.exit(main())

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