#!@PYTHON@ -tt
# - *- coding: utf- 8 - *-
#
#
# OCF resource agent to move an IP address within a VPC in GCP
#
# License: GNU General Public License (GPL)
# Copyright (c) 2018 Hervé Werner (MFG Labs)
# Copyright 2018 Google Inc.
# Based on code from Markus Guertler (aws-vpc-move-ip)
# All Rights Reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of version 2 of the GNU General Public License as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it would be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
#
# Further, this software is distributed without any warranty that it is
# free of the rightful claim of any third person regarding infringement
# or the like.  Any license provided herein, whether implied or
# otherwise, applies only to this software file.  Patent licenses, if
# any, provided herein do not apply to combinations of this program with
# other software, or any other product whatsoever.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write the Free Software Foundation,
# Inc., 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
#


#######################################################################

import atexit
import logging
import os
import sys
import time

OCF_FUNCTIONS_DIR = os.environ.get("OCF_FUNCTIONS_DIR", "%s/lib/heartbeat" % os.environ.get("OCF_ROOT"))
sys.path.append(OCF_FUNCTIONS_DIR)

from ocf import *

try:
  import googleapiclient.discovery
  import pyroute2
  try:
    from google.oauth2.service_account import Credentials as ServiceAccountCredentials
  except ImportError:
    from oauth2client.service_account import ServiceAccountCredentials
except ImportError:
  pass

if sys.version_info >= (3, 0):
  # Python 3 imports.
  import urllib.parse as urlparse
  import urllib.request as urlrequest
else:
  # Python 2 imports.
  import urllib as urlparse
  import urllib2 as urlrequest


GCP_API_URL_PREFIX = 'https://www.googleapis.com/compute/v1'
METADATA_SERVER = 'http://metadata.google.internal/computeMetadata/v1/'
METADATA_HEADERS = {'Metadata-Flavor': 'Google'}
METADATA = \
'''<?xml version="1.0"?>
<!DOCTYPE resource-agent SYSTEM "ra-api-1.dtd">
<resource-agent name="gcp-vpc-move-route" version="1.0">
<version>1.0</version>
<longdesc lang="en">
Resource Agent that can move a floating IP addresse within a GCP VPC by changing an
entry in the routing table. This agent also configures the floating IP locally
on the instance OS.
Requirements :
- IP forwarding must be enabled on all instances in order to be able to
terminate the route
- The floating IP address must be chosen so that it is outside all existing
subnets in the VPC network
- IAM permissions
(see https://cloud.google.com/compute/docs/access/iam-permissions) :
1) compute.routes.delete, compute.routes.get and compute.routes.update on the
route
2) compute.networks.updatePolicy on the network (to add a new route)
3) compute.networks.get on the network (to check the VPC network existence)
4) compute.routes.list on the project (to check conflicting routes)
</longdesc>
<shortdesc lang="en">Move IP within a GCP VPC</shortdesc>

<parameters>

<parameter name="ip" unique="1" required="1">
<longdesc lang="en">
Floating IP address. Note that this IP must be chosen outside of all existing
subnet ranges
</longdesc>
<shortdesc lang="en">Floating IP</shortdesc>
<content type="string" />
</parameter>

<parameter name="vpc_network" required="0">
<longdesc lang="en">
Name of the VPC network
</longdesc>
<shortdesc lang="en">VPC network</shortdesc>
<content type="string" default="default" />
</parameter>

<parameter name="project">
<longdesc lang="en">
Project ID of the instance. It can be useful to set this attribute if
the instance is in a shared service project. Otherwise, the agent should
be able to determine the project ID automatically.
</longdesc>
<shortdesc lang="en">Project ID</shortdesc>
<content type="string" default="default" />
</parameter>

<parameter name="interface">
<longdesc lang="en">
Name of the network interface
</longdesc>
<shortdesc lang="en">Network interface name</shortdesc>
<content type="string" default="eth0" />
</parameter>

<parameter name="route_name" unique="1">
<longdesc lang="en">
Route name
</longdesc>
<shortdesc lang="en">Route name</shortdesc>
<content type="string" default="ra-%s" />
</parameter>

<parameter name="serviceaccount">
<longdesc lang="en">Path to Service account JSON file</longdesc>
<shortdesc lang="en">Service account JSONfile</shortdesc>
<content type="string" default="" />
</parameter>

<parameter name="stackdriver_logging" unique="0" required="0">
<longdesc lang="en">If enabled (set to true), IP failover logs will be posted to stackdriver logging</longdesc>
<shortdesc lang="en">Stackdriver-logging support</shortdesc>
<content type="boolean" default="" />
</parameter>
</parameters>

<actions>
<action name="start" timeout="180s" />
<action name="stop" timeout="180s" />
<action name="monitor" depth="0" timeout="30s" interval="60s" />
<action name="validate-all" timeout="5s" />
<action name="meta-data" timeout="5s" />
</actions>
</resource-agent>
''' % os.path.basename(sys.argv[0])


class Context(object):
  __slots__ = 'conn', 'iface_idx', 'instance', 'instance_url', 'interface', \
      'ip', 'iproute', 'project', 'route_name', 'vpc_network', \
      'vpc_network_url', 'zone'


def wait_for_operation(ctx, response):
  """Blocks until operation completes.
  Code from GitHub's GoogleCloudPlatform/python-docs-samples

  Args:
    response: dict, a request's response
  """
  def _OperationGetter(response):
    operation = response[u'name']
    if response.get(u'zone'):
      return ctx.conn.zoneOperations().get(
          project=ctx.project, zone=ctx.zone, operation=operation)
    else:
      return ctx.conn.globalOperations().get(
          project=ctx.project, operation=operation)

  while True:
    result = _OperationGetter(response).execute()

    if result['status'] == 'DONE':
      if 'error' in result:
        raise Exception(result['error'])
      return result

    time.sleep(1)


def get_metadata(metadata_key, params=None, timeout=None):
  """Performs a GET request with the metadata headers.

  Args:
    metadata_key: string, the metadata to perform a GET request on.
    params: dictionary, the query parameters in the GET request.
    timeout: int, timeout in seconds for metadata requests.

  Returns:
    HTTP response from the GET request.

  Raises:
    urlerror.HTTPError: raises when the GET request fails.
  """
  timeout = timeout or 60
  metadata_url = os.path.join(METADATA_SERVER, metadata_key)
  params = urlparse.urlencode(params or {})
  url = '%s?%s' % (metadata_url, params)
  request = urlrequest.Request(url, headers=METADATA_HEADERS)
  request_opener = urlrequest.build_opener(urlrequest.ProxyHandler({}))
  return request_opener.open(request, timeout=timeout * 1.1).read().decode("utf-8")


def validate(ctx):
  if os.geteuid() != 0:
    logger.error('You must run this agent as root')
    sys.exit(OCF_ERR_PERM)

  try:
    serviceaccount = os.environ.get("OCF_RESKEY_serviceaccount")
    if not serviceaccount:
      try:
        from googleapiclient import _auth
        credentials = _auth.default_credentials();
      except:
        credentials = GoogleCredentials.get_application_default()
      logging.debug("using application default credentials")
    else:
      scope = ['https://www.googleapis.com/auth/cloud-platform']
      logging.debug("using credentials from service account")
      try:
        credentials = ServiceAccountCredentials.from_service_account_file(filename=serviceaccount, scopes=scope)
      except AttributeError:
        credentials = ServiceAccountCredentials.from_json_keyfile_name(serviceaccount, scope)
      except Exception as e:
        logging.error(str(e))
        sys.exit(OCF_ERR_GENERIC)
    ctx.conn = googleapiclient.discovery.build('compute', 'v1', credentials=credentials, cache_discovery=False)
  except Exception as e:
    logger.error('Couldn\'t connect with google api: ' + str(e))
    sys.exit(OCF_ERR_GENERIC)

  ctx.ip = os.environ.get('OCF_RESKEY_ip')
  if not ctx.ip:
    logger.error('Missing ip parameter')
    sys.exit(OCF_ERR_CONFIGURED)

  try:
    ctx.instance = get_metadata('instance/name')
    ctx.zone = get_metadata('instance/zone').split('/')[-1]
    ctx.project = os.environ.get(
        'OCF_RESKEY_project', get_metadata('project/project-id'))
  except Exception as e:
    logger.error(
        'Instance information not found. Is this a GCE instance ?: %s', str(e))
    sys.exit(OCF_ERR_GENERIC)

  ctx.instance_url = '%s/projects/%s/zones/%s/instances/%s' % (
      GCP_API_URL_PREFIX, ctx.project, ctx.zone, ctx.instance)
  ctx.vpc_network = os.environ.get('OCF_RESKEY_vpc_network', 'default')
  ctx.vpc_network_url = '%s/projects/%s/global/networks/%s' % (
      GCP_API_URL_PREFIX, ctx.project, ctx.vpc_network)
  ctx.interface = os.environ.get('OCF_RESKEY_interface', 'eth0')
  ctx.route_name = os.environ.get(
      'OCF_RESKEY_route_name', 'ra-%s' % os.path.basename(sys.argv[0]))
  ctx.iproute = pyroute2.IPRoute()
  atexit.register(ctx.iproute.close)
  idxs = ctx.iproute.link_lookup(ifname=ctx.interface)
  if not idxs:
    logger.error('Network interface not found')
    sys.exit(OCF_ERR_GENERIC)
  ctx.iface_idx = idxs[0]


def check_conflicting_routes(ctx):
  fl = '(destRange = "%s*") AND (network = "%s") AND (name != "%s")' % (
      ctx.ip, ctx.vpc_network_url, ctx.route_name)
  try:
    request = ctx.conn.routes().list(project=ctx.project, filter=fl)
    response = request.execute()
  except googleapiclient.errors.HttpError as e:
    if e.resp.status == 404:
      logger.error('VPC network not found')
      if 'stop' in sys.argv[1]:
        sys.exit(OCF_SUCCESS)
      else:
        sys.exit(OCF_ERR_CONFIGURED)
    else:
      raise

  route_list = response.get('items', None)
  if route_list:
    logger.error(
        'Conflicting unnmanaged routes for destination %s/32 in VPC %s found : %s',
        ctx.ip, ctx.vpc_network, str(route_list))
    sys.exit(OCF_ERR_CONFIGURED)


def route_release(ctx):
  request = ctx.conn.routes().delete(project=ctx.project, route=ctx.route_name)
  wait_for_operation(ctx, request.execute())


def ip_monitor(ctx):
  logger.info('IP monitor: checking local network configuration')

  def address_filter(addr):
    for attr in addr['attrs']:
      if attr[0] == 'IFA_LOCAL':
        if attr[1] == ctx.ip:
          return True
        else:
          return False

  route = ctx.iproute.get_addr(
      index=ctx.iface_idx, match=address_filter)
  if not route:
    logger.warning(
        'The floating IP %s is not locally configured on this instance (%s)',
        ctx.ip, ctx.instance)
    return OCF_NOT_RUNNING

  logger.debug(
      'The floating IP %s is correctly configured on this instance (%s)',
      ctx.ip, ctx.instance)
  return OCF_SUCCESS


def ip_release(ctx):
  ctx.iproute.addr('del', index=ctx.iface_idx, address=ctx.ip, mask=32)


def ip_and_route_start(ctx):
  logger.info('Bringing up the floating IP %s', ctx.ip)

  # Add a new entry in the routing table
  # If the route entry exists and is pointing to another instance, take it over

  # Ensure that there is no route that we are not aware of that is also handling our IP
  check_conflicting_routes(ctx)

  # There is no replace API, We need to first delete the existing route if any
  try:
    request = ctx.conn.routes().get(project=ctx.project, route=ctx.route_name)
    request.execute()
  # TODO: check specific exception for 404
  except googleapiclient.errors.HttpError as e:
    if e.resp.status != 404:
      raise
  else:
      route_release(ctx)

  route_body = {
      'name': ctx.route_name,
      'network': ctx.vpc_network_url,
      'destRange': '%s/32' % ctx.ip,
      'nextHopInstance': ctx.instance_url,
  }
  try:
    request = ctx.conn.routes().insert(project=ctx.project, body=route_body)
    wait_for_operation(ctx, request.execute())
  except googleapiclient.errors.HttpError:
    try:
      request = ctx.conn.networks().get(
          project=ctx.project, network=ctx.vpc_network)
      request.execute()
    except googleapiclient.errors.HttpError as e:
      if e.resp.status == 404:
        logger.error('VPC network not found')
        sys.exit(OCF_ERR_CONFIGURED)
      else:
        raise
    else:
      raise

  # Configure the IP address locally
  # We need to release the IP first
  if ip_monitor(ctx) == OCF_SUCCESS:
    ip_release(ctx)

  ctx.iproute.addr('add', index=ctx.iface_idx, address=ctx.ip, mask=32)
  ctx.iproute.link('set', index=ctx.iface_idx, state='up')
  logger.info('Successfully brought up the floating IP %s', ctx.ip)


def route_monitor(ctx):
  logger.info('GCP route monitor: checking route table')

  # Ensure that there is no route that we are not aware of that is also handling our IP
  check_conflicting_routes(ctx)

  try:
    request = ctx.conn.routes().get(project=ctx.project, route=ctx.route_name)
    response = request.execute()
  except googleapiclient.errors.HttpError as e:
    if e.resp.status == 404:
      return OCF_NOT_RUNNING
    elif 'Insufficient Permission' in e.content:
      return OCF_ERR_PERM
    else:
      raise

  routed_to_instance = response.get('nextHopInstance', '<unknown>')
  instance_url = '%s/projects/%s/zones/%s/instances/%s' % (
      GCP_API_URL_PREFIX, ctx.project, ctx.zone, ctx.instance)
  if routed_to_instance != instance_url:
    logger.warning(
        'The floating IP %s is not routed to this instance (%s) but to instance %s',
        ctx.ip, ctx.instance, routed_to_instance.split('/')[-1])
    return OCF_NOT_RUNNING

  logger.debug(
      'The floating IP %s is correctly routed to this instance (%s)',
      ctx.ip, ctx.instance)
  return OCF_SUCCESS


def ip_and_route_stop(ctx):
  logger.info('Bringing down the floating IP %s', ctx.ip)

  # Delete the route entry
  # If the route entry exists and is pointing to another instance, don't touch it
  if route_monitor(ctx) == OCF_NOT_RUNNING:
    logger.info(
        'The floating IP %s is already not routed to this instance (%s)',
        ctx.ip, ctx.instance)
  else:
    route_release(ctx)

  if ip_monitor(ctx) == OCF_NOT_RUNNING:
    logger.info('The floating IP %s is already down', ctx.ip)
  else:
    ip_release(ctx)


def configure_logs(ctx):
  # Prepare logging
  global logger
  logging.getLogger('googleapiclient').setLevel(logging.WARN)
  logging_env = os.environ.get('OCF_RESKEY_stackdriver_logging')
  if logging_env:
    logging_env = logging_env.lower()
    if any(x in logging_env for x in ['yes', 'true', 'enabled']):
      try:
        import google.cloud.logging.handlers
        client = google.cloud.logging.Client()
        handler = google.cloud.logging.handlers.CloudLoggingHandler(
            client, name=ctx.instance)
        handler.setLevel(logging.INFO)
        formatter = logging.Formatter('gcp:route "%(message)s"')
        handler.setFormatter(formatter)
        log.addHandler(handler)
        logger = logging.LoggerAdapter(log, {'OCF_RESOURCE_INSTANCE': OCF_RESOURCE_INSTANCE})
      except ImportError:
        logger.error('Couldn\'t import google.cloud.logging, '
            'disabling Stackdriver-logging support')


def main():
  if 'meta-data' in sys.argv[1]:
    print(METADATA)
    return

  ctx = Context()

  validate(ctx)
  if 'validate-all' in sys.argv[1]:
    return

  configure_logs(ctx)
  if 'start' in sys.argv[1]:
    ip_and_route_start(ctx)
  elif 'stop' in sys.argv[1]:
    ip_and_route_stop(ctx)
  elif 'status' in sys.argv[1] or 'monitor' in sys.argv[1]:
    sys.exit(ip_monitor(ctx))
  else:
    usage = 'usage: %s {start|stop|monitor|status|meta-data|validate-all}' % \
        os.path.basename(sys.argv[0])
    logger.error(usage)
    sys.exit(OCF_ERR_UNIMPLEMENTED)


if __name__ == "__main__":
  main()