# Copyright (C) 2015 Canonical Ltd.
#
# Author: Scott Moser <scott.moser@canonical.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

"""
Fan
---
**Summary:** configure ubuntu fan networking

This module installs, configures and starts the ubuntu fan network system. For
more information about Ubuntu Fan, see:
``https://wiki.ubuntu.com/FanNetworking``.

If cloud-init sees a ``fan`` entry in cloud-config it will:

    - write ``config_path`` with the contents of the ``config`` key
    - install the package ``ubuntu-fan`` if it is not installed
    - ensure the service is started (or restarted if was previously running)

**Internal name:** ``cc_fan``

**Module frequency:** per instance

**Supported distros:** ubuntu

**Config keys**::

    fan:
        config: |
            # fan 240
            10.0.0.0/8 eth0/16 dhcp
            10.0.0.0/8 eth1/16 dhcp off
            # fan 241
            241.0.0.0/8 eth0/16 dhcp
        config_path: /etc/network/fan
"""

from cloudinit import log as logging
from cloudinit.settings import PER_INSTANCE
from cloudinit import subp
from cloudinit import util

LOG = logging.getLogger(__name__)

frequency = PER_INSTANCE

BUILTIN_CFG = {
    'config': None,
    'config_path': '/etc/network/fan',
}


def stop_update_start(distro, service, config_file, content):
    try:
        distro.manage_service('stop', service)
        stop_failed = False
    except subp.ProcessExecutionError as e:
        stop_failed = True
        LOG.warning("failed to stop %s: %s", service, e)

    if not content.endswith('\n'):
        content += '\n'
    util.write_file(config_file, content, omode="w")

    try:
        distro.manage_service('start', service)
        if stop_failed:
            LOG.warning("success: %s started", service)
    except subp.ProcessExecutionError as e:
        LOG.warning("failed to start %s: %s", service, e)

    distro.manage_service('enable', service)


def handle(name, cfg, cloud, log, args):
    cfgin = cfg.get('fan')
    if not cfgin:
        cfgin = {}
    mycfg = util.mergemanydict([cfgin, BUILTIN_CFG])

    if not mycfg.get('config'):
        LOG.debug("%s: no 'fan' config entry. disabling", name)
        return

    util.write_file(mycfg.get('config_path'), mycfg.get('config'), omode="w")
    distro = cloud.distro
    if not subp.which('fanctl'):
        distro.install_packages(['ubuntu-fan'])

    stop_update_start(
        distro,
        service='ubuntu-fan', config_file=mycfg.get('config_path'),
        content=mycfg.get('config'))

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