X-Git-Url: https://osm.etsi.org/gitweb/?a=blobdiff_plain;f=src%2Femuvim%2Fdcemulator%2Fmonitoring.py;h=ba04771c5107d092700c570460dd2791c204b7e4;hb=36afe6369a9b6178525057a524a27fde59398b00;hp=094c09b352d513a7d0a63966b3bd4d2d490ab674;hpb=7f89ec08278873d335e15a9cf39034692c666bff;p=osm%2Fvim-emu.git

diff --git a/src/emuvim/dcemulator/monitoring.py b/src/emuvim/dcemulator/monitoring.py
index 094c09b..ba04771 100755
--- a/src/emuvim/dcemulator/monitoring.py
+++ b/src/emuvim/dcemulator/monitoring.py
@@ -1,26 +1,232 @@
-__author__ = 'Administrator'
+"""
+Copyright (c) 2015 SONATA-NFV
+ALL RIGHTS RESERVED.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+Neither the name of the SONATA-NFV [, ANY ADDITIONAL AFFILIATION]
+nor the names of its contributors may be used to endorse or promote
+products derived from this software without specific prior written
+permission.
+
+This work has been performed in the framework of the SONATA project,
+funded by the European Commission under Grant number 671517 through
+the Horizon 2020 and 5G-PPP programmes. The authors would like to
+acknowledge the contributions of their colleagues of the SONATA
+partner consortium (www.sonata-nfv.eu).
+"""
 
-import urllib2
 import logging
+import sys
 from mininet.node import  OVSSwitch
 import ast
+import time
+from prometheus_client import start_http_server, Summary, Histogram, Gauge, Counter, REGISTRY, CollectorRegistry, \
+    pushadd_to_gateway, push_to_gateway, delete_from_gateway
+import threading
+from subprocess import Popen
+import os
+
+
 logging.basicConfig(level=logging.INFO)
 
 """
-class to read openflow stats from the Ryu controller of the DCNEtwork
+class to read openflow stats from the Ryu controller of the DCNetwork
 """
 
 class DCNetworkMonitor():
     def __init__(self, net):
         self.net = net
-        # link to REST_API
-        self.ip = '0.0.0.0'
-        self.port = '8080'
-        self.REST_api = 'http://{0}:{1}'.format(self.ip,self.port)
 
+        # TODO: these global variables should be part of a config file?
+        '''
+        # prometheus is started outside of son-emu
+        prometheus_ip = '127.0.0.1'
+        prometheus_port = '9090'
+        self.prometheus_REST_api = 'http://{0}:{1}'.format(prometheus_ip, prometheus_port)
+        '''
+        # helper variables to calculate the metrics
+        # pushgateway is started outside of son-emu and son-emu is started with net=host
+        # so localhost:9091 works
+        self.pushgateway = 'localhost:9091'
+        # when sdk is started with docker-compose, we could use
+        # self.pushgateway = 'pushgateway:9091'
+
+        # supported Prometheus metrics
+        self.registry = CollectorRegistry()
+        self.prom_tx_packet_count = Gauge('sonemu_tx_count_packets', 'Total number of packets sent',
+                                          ['vnf_name', 'vnf_interface', 'flow_id'], registry=self.registry)
+        self.prom_rx_packet_count = Gauge('sonemu_rx_count_packets', 'Total number of packets received',
+                                          ['vnf_name', 'vnf_interface', 'flow_id'], registry=self.registry)
+        self.prom_tx_byte_count = Gauge('sonemu_tx_count_bytes', 'Total number of bytes sent',
+                                        ['vnf_name', 'vnf_interface', 'flow_id'], registry=self.registry)
+        self.prom_rx_byte_count = Gauge('sonemu_rx_count_bytes', 'Total number of bytes received',
+                                        ['vnf_name', 'vnf_interface', 'flow_id'], registry=self.registry)
+
+        self.prom_metrics={'tx_packets':self.prom_tx_packet_count, 'rx_packets':self.prom_rx_packet_count,
+                           'tx_bytes':self.prom_tx_byte_count,'rx_bytes':self.prom_rx_byte_count}
+
+        # list of installed metrics to monitor
+        # each entry can contain this data
+        '''
+        {
+        switch_dpid = 0
+        vnf_name = None
+        vnf_interface = None
+        previous_measurement = 0
+        previous_monitor_time = 0
+        metric_key = None
+        mon_port = None
+        }
+        '''
+        self.monitor_lock = threading.Lock()
+        self.monitor_flow_lock = threading.Lock()
+        self.network_metrics = []
+        self.flow_metrics = []
+
+        # start monitoring thread
+        self.start_monitoring = True
+        self.monitor_thread = threading.Thread(target=self.get_network_metrics)
+        self.monitor_thread.start()
+
+        self.monitor_flow_thread = threading.Thread(target=self.get_flow_metrics)
+        self.monitor_flow_thread.start()
+
+        # helper tools
+        # cAdvisor, Prometheus pushgateway and DB are started as external container, outside of son-emu
+
+
+    # first set some parameters, before measurement can start
+    def setup_flow(self, vnf_name, vnf_interface=None, metric='tx_packets', cookie=0):
+
+        flow_metric = {}
+
+        # check if port is specified (vnf:port)
+        if vnf_interface is None:
+            # take first interface by default
+            connected_sw = self.net.DCNetwork_graph.neighbors(vnf_name)[0]
+            link_dict = self.net.DCNetwork_graph[vnf_name][connected_sw]
+            vnf_interface = link_dict[0]['src_port_id']
+
+        flow_metric['vnf_name'] = vnf_name
+        flow_metric['vnf_interface'] = vnf_interface
+
+        vnf_switch = None
+        for connected_sw in self.net.DCNetwork_graph.neighbors(vnf_name):
+            link_dict = self.net.DCNetwork_graph[vnf_name][connected_sw]
+            for link in link_dict:
+                if link_dict[link]['src_port_id'] == vnf_interface:
+                    # found the right link and connected switch
+                    vnf_switch = connected_sw
+                    flow_metric['mon_port'] = link_dict[link]['dst_port_nr']
+                    break
+
+        if not vnf_switch:
+            logging.exception("vnf switch of {0}:{1} not found!".format(vnf_name, vnf_interface))
+            return "vnf switch of {0}:{1} not found!".format(vnf_name, vnf_interface)
+
+        try:
+            # default port direction to monitor
+            if metric is None:
+                metric = 'tx_packets'
+
+            next_node = self.net.getNodeByName(vnf_switch)
+
+            if not isinstance(next_node, OVSSwitch):
+                logging.info("vnf: {0} is not connected to switch".format(vnf_name))
+                return
+
+            flow_metric['previous_measurement'] = 0
+            flow_metric['previous_monitor_time'] = 0
+
+            flow_metric['switch_dpid'] = int(str(next_node.dpid), 16)
+            flow_metric['metric_key'] = metric
+            flow_metric['cookie'] = cookie
+
+            self.monitor_flow_lock.acquire()
+            self.flow_metrics.append(flow_metric)
+            self.monitor_flow_lock.release()
+
+            logging.info('Started monitoring flow:{3} {2} on {0}:{1}'.format(vnf_name, vnf_interface, metric, cookie))
+            return 'Started monitoring flow:{3} {2} on {0}:{1}'.format(vnf_name, vnf_interface, metric, cookie)
+
+        except Exception as ex:
+            logging.exception("setup_metric error.")
+            return ex.message
+
+    def stop_flow(self, vnf_name, vnf_interface=None, metric=None, cookie=0,):
+
+        # check if port is specified (vnf:port)
+        if vnf_interface is None and metric is not None:
+            # take first interface by default
+            connected_sw = self.net.DCNetwork_graph.neighbors(vnf_name)[0]
+            link_dict = self.net.DCNetwork_graph[vnf_name][connected_sw]
+            vnf_interface = link_dict[0]['src_port_id']
+
+        for flow_dict in self.flow_metrics:
+            if flow_dict['vnf_name'] == vnf_name and flow_dict['vnf_interface'] == vnf_interface \
+                    and flow_dict['metric_key'] == metric and flow_dict['cookie'] == cookie:
+
+                self.monitor_flow_lock.acquire()
+
+                self.flow_metrics.remove(flow_dict)
+
+                for collector in self.registry._collectors:
+                    if (vnf_name, vnf_interface, cookie) in collector._metrics:
+                        collector.remove(vnf_name, vnf_interface, cookie)
+
+                delete_from_gateway(self.pushgateway, job='sonemu-SDNcontroller')
+
+                self.monitor_flow_lock.release()
+
+                logging.info('Stopped monitoring flow {3}: {2} on {0}:{1}'.format(vnf_name, vnf_interface, metric, cookie))
+                return 'Stopped monitoring flow {3}: {2} on {0}:{1}'.format(vnf_name, vnf_interface, metric, cookie)
+
+        return 'Error stopping monitoring flow: {0} on {1}:{2}'.format(metric, vnf_name, vnf_interface)
+
+
+    # first set some parameters, before measurement can start
+    def setup_metric(self, vnf_name, vnf_interface=None, metric='tx_packets'):
+
+        network_metric = {}
+
+        # check if port is specified (vnf:port)
+        if vnf_interface is None:
+            # take first interface by default
+            connected_sw = self.net.DCNetwork_graph.neighbors(vnf_name)[0]
+            link_dict = self.net.DCNetwork_graph[vnf_name][connected_sw]
+            vnf_interface = link_dict[0]['src_port_id']
+
+        network_metric['vnf_name'] = vnf_name
+        network_metric['vnf_interface'] = vnf_interface
+
+        for connected_sw in self.net.DCNetwork_graph.neighbors(vnf_name):
+            link_dict = self.net.DCNetwork_graph[vnf_name][connected_sw]
+            for link in link_dict:
+                if link_dict[link]['src_port_id'] == vnf_interface:
+                    # found the right link and connected switch
+                    network_metric['mon_port'] = link_dict[link]['dst_port_nr']
+                    break
+
+        if 'mon_port' not in network_metric:
+            logging.exception("vnf interface {0}:{1} not found!".format(vnf_name,vnf_interface))
+            return "vnf interface {0}:{1} not found!".format(vnf_name,vnf_interface)
 
-    def get_rate(self, vnf_name, direction='tx'):
         try:
+            # default port direction to monitor
+            if metric is None:
+                metric = 'tx_packets'
+
             vnf_switch = self.net.DCNetwork_graph.neighbors(str(vnf_name))
 
             if len(vnf_switch) > 1:
@@ -33,30 +239,326 @@ class DCNetworkMonitor():
                 vnf_switch = vnf_switch[0]
             next_node = self.net.getNodeByName(vnf_switch)
 
-            if not isinstance( next_node, OVSSwitch ):
+            if not isinstance(next_node, OVSSwitch):
                 logging.info("vnf: {0} is not connected to switch".format(vnf_name))
                 return
 
-            mon_port = self.net.DCNetwork_graph[vnf_name][vnf_switch]['dst_port']
-            switch_dpid = x = int(str(next_node.dpid),16)
+            network_metric['previous_measurement'] = 0
+            network_metric['previous_monitor_time'] = 0
 
-            ret = self.REST_cmd('stats/port', switch_dpid)
-            port_stat_dict = ast.literal_eval(ret)
-            for port_stat in port_stat_dict[str(switch_dpid)]:
-                if port_stat['port_no'] == mon_port:
-                    return port_stat
-                    break
 
-            return ret
+            network_metric['switch_dpid'] = int(str(next_node.dpid), 16)
+            network_metric['metric_key'] = metric
+
+            self.monitor_lock.acquire()
+
+            self.network_metrics.append(network_metric)
+            self.monitor_lock.release()
+
+
+            logging.info('Started monitoring: {2} on {0}:{1}'.format(vnf_name, vnf_interface, metric))
+            return 'Started monitoring: {2} on {0}:{1}'.format(vnf_name, vnf_interface, metric)
 
         except Exception as ex:
-            logging.exception("get_txrate error.")
+            logging.exception("setup_metric error.")
             return ex.message
 
+    def stop_metric(self, vnf_name, vnf_interface=None, metric=None):
+
+        # check if port is specified (vnf:port)
+        if vnf_interface is None and metric is not None:
+            # take first interface by default
+            connected_sw = self.net.DCNetwork_graph.neighbors(vnf_name)[0]
+            link_dict = self.net.DCNetwork_graph[vnf_name][connected_sw]
+            vnf_interface = link_dict[0]['src_port_id']
+
+        for metric_dict in self.network_metrics:
+            if metric_dict['vnf_name'] == vnf_name and metric_dict['vnf_interface'] == vnf_interface \
+                    and metric_dict['metric_key'] == metric:
+
+                self.monitor_lock.acquire()
+
+                self.network_metrics.remove(metric_dict)
+
+                #this removes the complete metric, all labels...
+                #REGISTRY.unregister(self.prom_metrics[metric_dict['metric_key']])
+                #self.registry.unregister(self.prom_metrics[metric_dict['metric_key']])
+
+                for collector in self.registry._collectors :
+
+                    """
+                    INFO:root:name:sonemu_rx_count_packets
+                    labels:('vnf_name', 'vnf_interface')
+                    metrics:{(u'tsrc', u'output'): < prometheus_client.core.Gauge
+                    object
+                    at
+                    0x7f353447fd10 >}
+                    """
+                    logging.info('{0}'.format(collector._metrics.values()))
+
+                    if (vnf_name, vnf_interface, 'None') in collector._metrics:
+                        logging.info('2 name:{0} labels:{1} metrics:{2}'.format(collector._name, collector._labelnames,
+                                                                              collector._metrics))
+                        collector.remove(vnf_name, vnf_interface, 'None')
+
+                # set values to NaN, prometheus api currently does not support removal of metrics
+                #self.prom_metrics[metric_dict['metric_key']].labels(vnf_name, vnf_interface).set(float('nan'))
+
+                # this removes the complete metric, all labels...
+                # 1 single monitor job for all metrics of the SDN controller
+                # we can only  remove from the pushgateway grouping keys(labels) which we have defined for the add_to_pushgateway
+                # we can not specify labels from the metrics to be removed
+                # if we need to remove the metrics seperatelty, we need to give them a separate grouping key, and probably a diffferent registry also
+                delete_from_gateway(self.pushgateway, job='sonemu-SDNcontroller')
+
+                self.monitor_lock.release()
+
+                logging.info('Stopped monitoring: {2} on {0}:{1}'.format(vnf_name, vnf_interface, metric))
+                return 'Stopped monitoring: {2} on {0}:{1}'.format(vnf_name, vnf_interface, metric)
+
+            # delete everything from this vnf
+            elif metric_dict['vnf_name'] == vnf_name and vnf_interface is None and metric is None:
+                self.monitor_lock.acquire()
+                self.network_metrics.remove(metric_dict)
+                for collector in self.registry._collectors:
+                    collector_dict = collector._metrics.copy()
+                    for name, interface, id in collector_dict:
+                        if name == vnf_name:
+                            logging.info('3 name:{0} labels:{1} metrics:{2}'.format(collector._name, collector._labelnames,
+                                                                           collector._metrics))
+                            collector.remove(name, interface, 'None')
+
+                delete_from_gateway(self.pushgateway, job='sonemu-SDNcontroller')
+                self.monitor_lock.release()
+                logging.info('Stopped monitoring vnf: {0}'.format(vnf_name))
+                return 'Stopped monitoring: {0}'.format(vnf_name)
+
+        return 'Error stopping monitoring metric: {0} on {1}:{2}'.format(metric, vnf_name, vnf_interface)
+
+
+
+
+
+# get all metrics defined in the list and export it to Prometheus
+    def get_flow_metrics(self):
+        while self.start_monitoring:
+
+            self.monitor_flow_lock.acquire()
+
+            for flow_dict in self.flow_metrics:
+                data = {}
+
+                data['cookie'] = flow_dict['cookie']
+                data['cookie_mask'] = flow_dict['cookie']
+
+                if 'tx' in flow_dict['metric_key']:
+                    data['match'] = {'in_port':flow_dict['mon_port']}
+                elif 'rx' in flow_dict['metric_key']:
+                    data['out_port'] = flow_dict['mon_port']
+
+
+                # query Ryu
+                ret = self.net.ryu_REST('stats/flow', dpid=flow_dict['switch_dpid'], data=data)
+                if isinstance(ret, dict):
+                    flow_stat_dict = ret
+                elif isinstance(ret, basestring):
+                    flow_stat_dict = ast.literal_eval(ret.rstrip())
+                else:
+                    flow_stat_dict = None
+
+                logging.debug('received flow stat:{0} '.format(flow_stat_dict))
+
+                self.set_flow_metric(flow_dict, flow_stat_dict)
+
+            self.monitor_flow_lock.release()
+            time.sleep(1)
+
+    def get_network_metrics(self):
+        while self.start_monitoring:
+
+            self.monitor_lock.acquire()
+
+            # group metrics by dpid to optimize the rest api calls
+            dpid_list = [metric_dict['switch_dpid'] for metric_dict in self.network_metrics]
+            dpid_set = set(dpid_list)
+
+            for dpid in dpid_set:
+
+                # query Ryu
+                ret = self.net.ryu_REST('stats/port', dpid=dpid)
+                port_stat_dict = ast.literal_eval(ret)
+
+                metric_list = [metric_dict for metric_dict in self.network_metrics
+                               if int(metric_dict['switch_dpid'])==int(dpid)]
+
+                for metric_dict in metric_list:
+                    self.set_network_metric(metric_dict, port_stat_dict)
+
+            self.monitor_lock.release()
+            time.sleep(1)
+
+    # add metric to the list to export to Prometheus, parse the Ryu port-stats reply
+    def set_network_metric(self, metric_dict, port_stat_dict):
+        # vnf tx is the datacenter switch rx and vice-versa
+        metric_key = self.switch_tx_rx(metric_dict['metric_key'])
+        switch_dpid = metric_dict['switch_dpid']
+        vnf_name = metric_dict['vnf_name']
+        vnf_interface = metric_dict['vnf_interface']
+        previous_measurement = metric_dict['previous_measurement']
+        previous_monitor_time = metric_dict['previous_monitor_time']
+        mon_port = metric_dict['mon_port']
+
+        for port_stat in port_stat_dict[str(switch_dpid)]:
+            if int(port_stat['port_no']) == int(mon_port):
+                port_uptime = port_stat['duration_sec'] + port_stat['duration_nsec'] * 10 ** (-9)
+                this_measurement = int(port_stat[metric_key])
+
+                # set prometheus metric
+                self.prom_metrics[metric_dict['metric_key']].\
+                    labels({'vnf_name': vnf_name, 'vnf_interface': vnf_interface, 'flow_id': None}).\
+                    set(this_measurement)
+
+                # 1 single monitor job for all metrics of the SDN controller
+                pushadd_to_gateway(self.pushgateway, job='sonemu-SDNcontroller', registry=self.registry)
+
+                # also the rate is calculated here, but not used for now
+                # (rate can be easily queried from prometheus also)
+                if previous_monitor_time <= 0 or previous_monitor_time >= port_uptime:
+                    metric_dict['previous_measurement'] = int(port_stat[metric_key])
+                    metric_dict['previous_monitor_time'] = port_uptime
+                    # do first measurement
+                    time.sleep(1)
+                    self.monitor_lock.release()
+
+                    metric_rate = self.get_network_metrics()
+                    return metric_rate
+
+                else:
+                    time_delta = (port_uptime - metric_dict['previous_monitor_time'])
+                    metric_rate = (this_measurement - metric_dict['previous_measurement']) / float(time_delta)
+
+                metric_dict['previous_measurement'] = this_measurement
+                metric_dict['previous_monitor_time'] = port_uptime
+                return metric_rate
+
+        logging.exception('metric {0} not found on {1}:{2}'.format(metric_key, vnf_name, vnf_interface))
+        return 'metric {0} not found on {1}:{2}'.format(metric_key, vnf_name, vnf_interface)
+
+    def set_flow_metric(self, metric_dict, flow_stat_dict):
+        # vnf tx is the datacenter switch rx and vice-versa
+        metric_key = metric_dict['metric_key']
+        switch_dpid = metric_dict['switch_dpid']
+        vnf_name = metric_dict['vnf_name']
+        vnf_interface = metric_dict['vnf_interface']
+        previous_measurement = metric_dict['previous_measurement']
+        previous_monitor_time = metric_dict['previous_monitor_time']
+        cookie = metric_dict['cookie']
+
+        counter = 0
+        for flow_stat in flow_stat_dict[str(switch_dpid)]:
+            if 'bytes' in metric_key:
+                counter += flow_stat['byte_count']
+            elif 'packet' in metric_key:
+                counter += flow_stat['packet_count']
+
+        flow_stat = flow_stat_dict[str(switch_dpid)][0]
+        flow_uptime = flow_stat['duration_sec'] + flow_stat['duration_nsec'] * 10 ** (-9)
+
+        self.prom_metrics[metric_dict['metric_key']]. \
+            labels({'vnf_name': vnf_name, 'vnf_interface': vnf_interface, 'flow_id': cookie}). \
+            set(counter)
+        try:
+            pushadd_to_gateway(self.pushgateway, job='sonemu-SDNcontroller', registry=self.registry)
+        except Exception, e:
+            logging.warning("Pushgateway not reachable: {0} {1}".format(Exception, e))
+
+
+    def start_Prometheus(self, port=9090):
+        # prometheus.yml configuration file is located in the same directory as this file
+        cmd = ["docker",
+               "run",
+               "--rm",
+               "-p", "{0}:9090".format(port),
+               "-v", "{0}/prometheus.yml:/etc/prometheus/prometheus.yml".format(os.path.dirname(os.path.abspath(__file__))),
+               "-v", "{0}/profile.rules:/etc/prometheus/profile.rules".format(os.path.dirname(os.path.abspath(__file__))),
+               "--name", "prometheus",
+               "prom/prometheus"
+               ]
+        logging.info('Start Prometheus container {0}'.format(cmd))
+        return Popen(cmd)
+
+    def start_PushGateway(self, port=9091):
+        cmd = ["docker",
+               "run",
+               "-d",
+               "-p", "{0}:9091".format(port),
+               "--name", "pushgateway",
+               "prom/pushgateway"
+               ]
+
+        logging.info('Start Prometheus Push Gateway container {0}'.format(cmd))
+        return Popen(cmd)
+
+    def start_cadvisor(self, port=8090):
+        cmd = ["docker",
+               "run",
+               "--rm",
+               "--volume=/:/rootfs:ro",
+               "--volume=/var/run:/var/run:rw",
+               "--volume=/sys:/sys:ro",
+               "--volume=/var/lib/docker/:/var/lib/docker:ro",
+               "--publish={0}:8080".format(port),
+               "--name=cadvisor",
+               "google/cadvisor:latest"
+               ]
+        logging.info('Start cAdvisor container {0}'.format(cmd))
+        return Popen(cmd)
+
+    def stop(self):
+        # stop the monitoring thread
+        self.start_monitoring = False
+        self.monitor_thread.join()
+        self.monitor_flow_thread.join()
+
+        # these containers are used for monitoring but are started now outside of son-emu
+        '''
+        if self.prometheus_process is not None:
+            logging.info('stopping prometheus container')
+            self.prometheus_process.terminate()
+            self.prometheus_process.kill()
+            self._stop_container('prometheus')
+
+        if self.pushgateway_process is not None:
+            logging.info('stopping pushgateway container')
+            self.pushgateway_process.terminate()
+            self.pushgateway_process.kill()
+            self._stop_container('pushgateway')
+
+        if self.cadvisor_process is not None:
+            logging.info('stopping cadvisor container')
+            self.cadvisor_process.terminate()
+            self.cadvisor_process.kill()
+            self._stop_container('cadvisor')
+        '''
+
+    def switch_tx_rx(self,metric=''):
+        # when monitoring vnfs, the tx of the datacenter switch is actually the rx of the vnf
+        # so we need to change the metric name to be consistent with the vnf rx or tx
+        if 'tx' in metric:
+            metric = metric.replace('tx','rx')
+        elif 'rx' in metric:
+            metric = metric.replace('rx','tx')
+
+        return metric
+
+    def _stop_container(self, name):
+        cmd = ["docker",
+               "stop",
+               name]
+        Popen(cmd).wait()
 
+        cmd = ["docker",
+               "rm",
+               name]
+        Popen(cmd).wait()
 
-    def REST_cmd(self, prefix, dpid):
-        url = self.REST_api + '/' + str(prefix) + '/' + str(dpid)
-        req = urllib2.Request(url)
-        ret = urllib2.urlopen(req).read()
-        return ret
\ No newline at end of file