Add element to bring up bridge on infra cloud

This will grab the content present on config drive, and
will create a bridge in top of network interface.

Change-Id: I7b6788ad2640650329d80114439d731d51dab340

files/elements/infra-cloud-bridge/README.rst

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+==================
+infra-cloud-bridge
+==================
+Installs an upstart script that will depend on glean, and
+will configure bridge for our infra cloud.

files/elements/infra-cloud-bridge/element-deps

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+dib-init-system
+install-static
+package-installs
+simple-init

files/elements/infra-cloud-bridge/init-scripts/upstart/create_bridge.conf

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+description "create bridge for infra cloud"
+
+console output
+
+start on (stopped glean and net-device-up IFACE!=lo)
+
+script
+    exec python /opt/create_bridge.py
+end script

files/elements/infra-cloud-bridge/package-installs.yaml

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+bridge-utils:
+net-tools:

files/elements/infra-cloud-bridge/static/opt/create_bridge.py

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+#!/usr/bin/python
+# Copyright (c) 2016 Yolanda Robla
+# Copyright (c) 2016 Hewlett-Packard Development Company, L.P.
+#
+# 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.
+
+import json
+import os
+import subprocess
+import sys
+
+from glean import systemlock
+from glean.cmd import get_config_drive_interfaces, get_sys_interfaces
+
+
+def configure_bridge(interface, interface_name, bridge_name, vlan_raw_device):
+    if interface['vlan_id']:
+        vlan_content = 'vlan-raw-device %s' % vlan_raw_device
+    else:
+        vlan_content = ''
+
+    network_file = '/etc/network/interfaces.d/%s.cfg' % interface_name
+
+    # generate content depending on data
+    file_content = """
+auto {net_name}
+iface {net_name} inet manual
+{vlan_content}
+
+auto {bridge_name}
+iface {bridge_name} inet static
+    bridge_ports {net_name}
+    bridge_hello 2
+    bridge_maxage 12
+    bridge_stp off
+    address {ipv4_address}
+    netmask {netmask}
+    gateway {gateway}
+    dns-nameservers {nameservers}
+
+"""
+
+    file_content = file_content.format(
+        net_name=interface_name, vlan_content=vlan_content,
+        bridge_name=bridge_name,
+        ipv4_address=interface['ip_address'],
+        netmask=interface['netmask'],
+        gateway=interface['routes'][0]['gateway'],
+        nameservers=' '.join(interface['dns_nameservers']))
+
+    with open(network_file, 'w') as target_file:
+        target_file.write(file_content)
+
+    # turn down pre-existing interface and start the bridge
+    # because at this point, glean has already configured
+    # previous interface that needs to be overriden.
+    # This will only happen at first time that the bridge
+    # is configured, because on reboots, we won't reach this
+    # configure_bridge method
+    subprocess.call(['ifdown', interface_name])
+    subprocess.call(['ifup', bridge_name])
+
+
+# mock object to interact with glean
+class MockArgs(object):
+    pass
+
+
+def main():
+    network_info_file = '/mnt/config/openstack/latest/network_info.json'
+
+    params = MockArgs()
+    setattr(params, 'root', '/')
+    setattr(params, 'noop', False)
+    sys_interfaces = get_sys_interfaces(None, params)
+
+    network_info = {}
+    if os.path.exists(network_info_file):
+        network_info = json.load(open(network_info_file))
+
+    if not network_info:
+        # we do not have entries on configdrive, skip
+        sys.exit(0)
+
+    interfaces = get_config_drive_interfaces(network_info)
+    interface = interfaces[interfaces.keys()[0]]
+    interface_name = sys_interfaces[interfaces.keys()[0]]
+
+    if 'vlan_id' in interface:
+        if interface['vlan_id'] in interface_name:
+            # if we find the entry for the already configured vlan, trim it
+            interface_name = interface_name.replace(
+                '.' + interface['vlan_id'], '')
+
+        vlan_raw_device = interface_name
+        interface_name = "{0}.{1}".format(
+            vlan_raw_device, interface['vlan_id'])
+
+    # generate bridge name
+    if 'vlan_id' in interface:
+        bridge_name = 'br-vlan%s' % interface['vlan_id']
+    else:
+        bridge_name = 'br-eth'
+
+    # only configure bridge if not exists
+    if not os.path.exists('/sys/class/net/%s' % bridge_name):
+        configure_bridge(interface, interface_name,
+                         bridge_name, vlan_raw_device)
+
+if __name__ == '__main__':
+    with systemlock.Lock('/tmp/glean.lock'):
+        sys.exit(main())