Set Azure to only update metadata on BOOT_NEW_INSTANCE (#1006)

In #834, we refactored the handling of events for fetching new metadata.
Previously, in Azure's __init__, the BOOT event was added to the
update_events, so it was assumed that Azure required the standard BOOT
behavior, which is to apply metadata twice every boot: once during
local-init, then again during standard init phase.
https://github.com/canonical/cloud-init/blob/21.2/cloudinit/sources/DataSourceAzure.py#L356

However, this line was effectively meaningless. After the metadata was
fetched in local-init, it was then pickled out to disk. Because
"update_events" was a class variable, the EventType.BOOT was not
persisted into the pickle. When the pickle was then unpickled in the
init phase, metadata did not get re-fetched because EventType.BOOT was
not present, so Azure is effectely only BOOT_NEW_INSTANCE.

Fetching metadata twice during boot causes some issue for
pre-provisioning on Azure because updating metadata during
re-provisioning will cause cloud-init to poll for reprovisiondata again
in DataSourceAzure, which will infinitely return 404(reprovisiondata
is deleted from IMDS after health signal was sent by cloud-init during
init-local). This makes cloud-init stuck in 'init'

1 files changed, 1 insertions, 8 deletions

diff --git a/cloudinit/sources/DataSourceAzure.py b/cloudinit/sources/DataSourceAzure.py
index caffa944..3fb564c8 100755
--- a/cloudinit/sources/DataSourceAzure.py
+++ b/cloudinit/sources/DataSourceAzure.py
@@ -22,7 +22,7 @@ import requests
 from cloudinit import dmi
 from cloudinit import log as logging
 from cloudinit import net
-from cloudinit.event import EventScope, EventType
+from cloudinit.event import EventType
 from cloudinit.net import device_driver
 from cloudinit.net.dhcp import EphemeralDHCPv4
 from cloudinit import sources
@@ -339,13 +339,6 @@ def temporary_hostname(temp_hostname, cfg, hostname_command='hostname'):
 class DataSourceAzure(sources.DataSource):
 
     dsname = 'Azure'
-    # Regenerate network config new_instance boot and every boot
-    default_update_events = {EventScope.NETWORK: {
-        EventType.BOOT_NEW_INSTANCE,
-        EventType.BOOT,
-        EventType.BOOT_LEGACY
-    }}
-
     _negotiated = False
     _metadata_imds = sources.UNSET
     _ci_pkl_version = 1