Cloudinit changes to change VM network via dhcp in Azure.

cloudinit/config/cc_setup_azure_networking.py

@@ -0,0 +1,52 @@
+#    Copyright (C) Microsoft Corp.
+#
+#    Author: Tamilmani Manoharan <tamanoha@microsoft.com>
+#
+# This file is part of cloud-init. See LICENSE file for license information.
+
+"""
+Setup Azure Networking
+------------------
+**Summary:** sets up networking required only for azure virtual machines.
+
+This module handles any specific networking requirements for azure virtual machines (VMs).
+In the present implementation, it handles moving a virtual machine from one azure virtual
+network to another.
+
+**Internal name:** ``cc_setup_azure_networking``
+
+**Module frequency:** per instance
+
+**Supported distros:** all
+"""
+
+from cloudinit.settings import PER_ALWAYS
+import time
+import os
+import socket
+import struct
+import glob
+from subprocess import Popen
+from cloudinit import importer
+from cloudinit import config
+from cloudinit import type_utils
+
+frequency = PER_ALWAYS
+
+def IsAzure():
+    azure_config_exists = False
+    for n in glob.glob("/etc/cloud/cloud.cfg.d/*azure.cfg"):
+         if os.path.isfile(n): 
+             azure_config_exists=True
+    return azure_config_exists
+
+def handle(name, _cfg, _cloud, log, _args): 
+    if IsAzure():
+        configs_dir = os.path.dirname(os.path.abspath(__file__))
+        log.debug("config dir %s", configs_dir)
+        proc = Popen(["python", configs_dir + "/../sources/helpers/azuredhcpagent.py"])
+        log.debug("Created netagent process")
+
+
+
+

cloudinit/sources/helpers/azuredhcpagent.py

@@ -0,0 +1,125 @@
+# Author: Tamilmani Manoharan <tamanoha@microsoft.com>
+#
+# This file is part of cloud-init. See LICENSE file for license information.
+
+import sys
+import logging
+import socket
+import os
+import struct
+import subprocess
+from logging.handlers import RotatingFileHandler
+
+RTMGRP_LINK = 1
+NLMSG_NOOP = 1
+NLMSG_ERROR = 2
+RTM_NEWLINK = 16
+RTM_DELLINK = 17
+IFLA_IFNAME = 3
+
+def GetLogger():
+    log = logging.getLogger("azuredhcpagent")
+    log.setLevel(logging.DEBUG)
+    formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(filename)s:%(lineno)s - %(message)s')
+
+    handler = RotatingFileHandler("/var/log/azuredhcpagent.log", maxBytes=10485760,
+                                  backupCount=5)
+
+    handler.setFormatter(formatter)
+    log.addHandler(handler)
+    return log
+
+def main():
+
+    log = GetLogger()
+    # Create the netlink socket and bind to RTMGRP_LINK,
+    s = socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, socket.NETLINK_ROUTE)
+    s.bind((os.getpid(), RTMGRP_LINK))
+
+    while True:
+
+        data = s.recv(65535)
+        msg_len, msg_type, flags, seq, pid = struct.unpack("=LHHLL", data[:16])
+
+        if msg_type == NLMSG_NOOP:
+            log.debug("noop")
+            continue
+        elif msg_type == NLMSG_ERROR:
+            log.debug("error")
+            break
+
+        # We fundamentally only care about NEWLINK messages in this version.
+        if msg_type != RTM_NEWLINK:
+            continue
+
+        data = data[16:]
+
+        family, _, if_type, index, flags, change = struct.unpack("=BBHiII", data[:16])
+
+        remaining = msg_len - 32
+        data = data[16:]
+
+        while remaining:
+            rta_len, rta_type = struct.unpack("=HH", data[:4])
+
+            # This check comes from RTA_OK, and terminates a string of routing
+            # attributes.
+            if rta_len < 4:
+                break
+
+            rta_data = data[4:rta_len]
+
+            increment = (rta_len + 4 - 1) & ~(4 - 1)
+            data = data[increment:]
+            remaining -= increment
+
+            # The link is up!
+            if rta_type == IFLA_IFNAME:
+                log.debug("New link %s", rta_data)
+                ifname = str(rta_data).strip('\0')
+
+                operfilename = "/sys/class/net/" + ifname + "/operstate"
+                operfilename = operfilename.strip("\0")
+                carrierfilename = "/sys/class/net/" + ifname + "/carrier"
+                carrierfilename = carrierfilename.strip("\0")
+
+                log.debug("operfilename %s", operfilename)
+
+                carrier=""
+                operstate=""
+
+                try:
+                    file = open(operfilename, "r")
+                    operstate = file.readline()
+                    file.close()                    
+                except Exception as e:
+                    log.error("exception reading operstate %s", str(e))
+
+                operstate = operstate.rstrip()
+                log.debug("operstate %s", operstate)
+
+                try:
+                    file = open(carrierfilename, "r")
+                    carrier = file.readline()
+                    file.close()
+
+                except IOError as io:
+                    if io.errno != 22:
+                        log.error("IO error reading carrier %s errno %d", str(io), io.errno)    
+
+                except Exception as e:
+                    log.error("exception reading carrier %s", str(e))
+
+
+                carrier = carrier.rstrip()
+                log.debug("carrier %s", carrier)
+
+                if operstate == "up" or carrier == "1":
+                    log.debug("trigger dhcp")
+                    # assuming dhclient exists
+                    return_code = subprocess.call("dhclient " + ifname, shell=True)
+                    log.debug("dhclient return status %d", return_code)
+
+
+if __name__ == '__main__':
+    main()

config/cloud.cfg.tmpl

@@ -125,7 +125,8 @@ cloud_final_modules:
  - phone-home
  - final-message
  - power-state-change
-
+ - setup-azure-networking
+
 # System and/or distro specific settings
 # (not accessible to handlers/transforms)
 system_info: