azure: Add reported ready marker file.

This change is for Azure VM Preprovisioning. A bug was found when after
azure VMs report ready the first time, during the time when VM is polling
indefinitely for the new ovf-env.xml from Instance Metadata Service
(IMDS), if a reboot happens, we send another report ready signal to the
fabric, which deletes the reprovisioning data on the node.

This marker file is used to fix this issue so that we will only send a
report ready signal to the fabric when no marker file is present. Then,
create a marker file so that when a reboot does occur, we check if a
marker file has been created and decide whether we would like to send the
repot ready signal.

LP: #1765214

1 files changed, 15 insertions, 6 deletions

diff --git a/cloudinit/sources/DataSourceAzure.py b/cloudinit/sources/DataSourceAzure.py
index a71197a6..1b03d460 100644
--- a/cloudinit/sources/DataSourceAzure.py
+++ b/cloudinit/sources/DataSourceAzure.py
@@ -48,6 +48,7 @@ DEFAULT_FS = 'ext4'
 # DMI chassis-asset-tag is set static for all azure instances
 AZURE_CHASSIS_ASSET_TAG = '7783-7084-3265-9085-8269-3286-77'
 REPROVISION_MARKER_FILE = "/var/lib/cloud/data/poll_imds"
+REPORTED_READY_MARKER_FILE = "/var/lib/cloud/data/reported_ready"
 IMDS_URL = "http://169.254.169.254/metadata/reprovisiondata"
 
 
@@ -436,11 +437,12 @@ class DataSourceAzure(sources.DataSource):
             LOG.debug("negotiating already done for %s",
                       self.get_instance_id())
 
-    def _poll_imds(self, report_ready=True):
+    def _poll_imds(self):
         """Poll IMDS for the new provisioning data until we get a valid
         response. Then return the returned JSON object."""
         url = IMDS_URL + "?api-version=2017-04-02"
         headers = {"Metadata": "true"}
+        report_ready = bool(not os.path.isfile(REPORTED_READY_MARKER_FILE))
         LOG.debug("Start polling IMDS")
 
         def exc_cb(msg, exception):
@@ -450,13 +452,17 @@ class DataSourceAzure(sources.DataSource):
             # call DHCP and setup the ephemeral network to acquire the new IP.
             return False
 
-        need_report = report_ready
         while True:
             try:
                 with EphemeralDHCPv4() as lease:
-                    if need_report:
+                    if report_ready:
+                        path = REPORTED_READY_MARKER_FILE
+                        LOG.info(
+                            "Creating a marker file to report ready: %s", path)
+                        util.write_file(path, "{pid}: {time}\n".format(
+                            pid=os.getpid(), time=time()))
                         self._report_ready(lease=lease)
-                        need_report = False
+                        report_ready = False
                     return readurl(url, timeout=1, headers=headers,
                                    exception_cb=exc_cb, infinite=True).contents
             except UrlError:
@@ -490,8 +496,10 @@ class DataSourceAzure(sources.DataSource):
         if (cfg.get('PreprovisionedVm') is True or
                 os.path.isfile(path)):
             if not os.path.isfile(path):
-                LOG.info("Creating a marker file to poll imds")
-                util.write_file(path, "%s: %s\n" % (os.getpid(), time()))
+                LOG.info("Creating a marker file to poll imds: %s",
+                         path)
+                util.write_file(path, "{pid}: {time}\n".format(
+                    pid=os.getpid(), time=time()))
             return True
         return False
 
@@ -526,6 +534,7 @@ class DataSourceAzure(sources.DataSource):
                 "Error communicating with Azure fabric; You may experience."
                 "connectivity issues.", exc_info=True)
             return False
+        util.del_file(REPORTED_READY_MARKER_FILE)
         util.del_file(REPROVISION_MARKER_FILE)
         return fabric_data