fix network interface restart in RHEL9 (Azure#2592)

Author: nagworld9

azurelinuxagent/common/osutil/factory.py

@@ -34,7 +34,7 @@
 from .nsbsd import NSBSDOSUtil
 from .openbsd import OpenBSDOSUtil
 from .openwrt import OpenWRTOSUtil
-from .redhat import RedhatOSUtil, Redhat6xOSUtil
+from .redhat import RedhatOSUtil, Redhat6xOSUtil, RedhatOSModernUtil
 from .suse import SUSEOSUtil, SUSE11OSUtil
 from .photonos import PhotonOSUtil
 from .ubuntu import UbuntuOSUtil, Ubuntu12OSUtil, Ubuntu14OSUtil, \
@@ -107,6 +107,9 @@ def _get_osutil(distro_name, distro_code_name, distro_version, distro_full_name)
         if Version(distro_version) < Version("7"):
             return Redhat6xOSUtil()
 
+        if Version(distro_version) == Version("8.6") or Version(distro_version) > Version("9"):
+            return RedhatOSModernUtil()
+
         return RedhatOSUtil()
 
     if distro_name == "euleros":

azurelinuxagent/common/osutil/redhat.py

@@ -142,3 +142,25 @@ def get_dhcp_lease_endpoint(self):
             endpoint = self.get_endpoint_from_leases_path('/var/lib/NetworkManager/dhclient-*.lease')
 
         return endpoint
+
+
+class RedhatOSModernUtil(RedhatOSUtil):
+    def __init__(self):  # pylint: disable=W0235
+        super(RedhatOSModernUtil, self).__init__()
+
+    def restart_if(self, ifname, retries=3, wait=5):
+        """
+        Restart an interface by bouncing the link. systemd-networkd observes
+        this event, and forces a renew of DHCP.
+        """
+        retry_limit = retries + 1
+        for attempt in range(1, retry_limit):
+            return_code = shellutil.run("ip link set {0} down && ip link set {0} up".format(ifname))
+            if return_code == 0:
+                return
+            logger.warn("failed to restart {0}: return code {1}".format(ifname, return_code))
+            if attempt < retry_limit:
+                logger.info("retrying in {0} seconds".format(wait))
+                time.sleep(wait)
+            else:
+                logger.warn("exceeded restart retries")