azure: /run/cloud-init/cloud-id broken symlink across reboot.

[ubuntu-server-builder]

This bug was originally filed in Launchpad as LP: #1998998

Launchpad details

affected_projects = []
assignee = None
assignee_name = None
date_closed = 2023-02-22T16:52:32.106568+00:00
date_created = 2022-12-07T04:37:33.678461+00:00
date_fix_committed = 2023-02-22T16:52:32.106568+00:00
date_fix_released = 2023-02-22T16:52:32.106568+00:00
id = 1998998
importance = high
is_complete = True
lp_url = https://bugs.launchpad.net/cloud-init/+bug/1998998
milestone = None
owner = chad.smith
owner_name = Chad Smith
private = False
status = fix_released
submitter = chad.smith
submitter_name = Chad Smith
tags = ['bitesize']
duplicates = []

Launchpad user Chad Smith(chad.smith) wrote on 2022-12-07T04:37:33.678461+00:00

cloud-init 22.4.2

On Azure, datasource details change across reboot cloud-init incorrectly removes /run/cloud-init/cloud-id-azure symlink.

2022-12-07 04:14:17,920 - util.py[DEBUG]: Creating symbolic link from '/run/cloud-init/cloud-id' => '/run/cloud-init/cloud-id-azure'
2022-12-07 04:14:17,920 - util.py[DEBUG]: Attempting to remove /run/cloud-init/cloud-id-azure

FRESH LAUNCH

ubuntu@test-focal:$ ls -l /run/cloud-init/cloud-id
lrwxrwxrwx 1 root root 30 Dec 7 04:10 /run/cloud-init/cloud-id -> /run/cloud-init/cloud-id-azure
ubuntu@test-focal:$ grep cloud-id /var/log/cloud-init.log
2022-12-07 04:10:34,734 - util.py[DEBUG]: Writing to /run/cloud-init/cloud-id-azure - wb: [644] 6 bytes
2022-12-07 04:10:34,735 - util.py[DEBUG]: Creating symbolic link from '/run/cloud-init/cloud-id' => '/run/cloud-init/cloud-id-azure'

ACROSS REBOOT

ubuntu@test-focal:~$ ls -l /run/cloud-init/cloud-id
lrwxrwxrwx 1 root root 30 Dec 7 04:14 /run/cloud-init/cloud-id -> /run/cloud-init/cloud-id-azure

2022-12-07 04:14:17,920 - util.py[DEBUG]: Writing to /run/cloud-init/cloud-id-azure - wb: [644] 6 bytes
2022-12-07 04:14:17,920 - util.py[DEBUG]: Creating symbolic link from '/run/cloud-init/cloud-id' => '/run/cloud-init/cloud-id-azure'
2022-12-07 04:14:17,920 - util.py[DEBUG]: Attempting to remove /run/cloud-init/cloud-id-azure

It looks like the symlink cleanup logic introduced in 217ef6b (which was released in cloud-init v. 21.4) doesn't do a proper comparison of previous-datasource to current datasource

Debug logs added to https://github.com/canonical/cloud-init/blob/main/cloudinit/sources/__init__.py#L443 shows that we are comparing the incorrect source file /root/cloud-init/cloud-id versus actually comparing the cloud-specific symlink name /run/cloud-init/cloud-id-, resulting in a removal of the cloud-specific link name across reboot.

2022-12-07 04:25:58,162 - init.py[WARNING]: previous_cloud_id_file /run/cloud-init/cloud-id-azure != cloud_id_file /run/cloud-init/cloud-id

Likely all we need is a correction in logic like the following:
diff --git a/cloudinit/sources/init.py b/cloudinit/sources/init.py
index 85e094ac5..3fb08ead2 100644
--- a/cloudinit/sources/init.py
+++ b/cloudinit/sources/init.py
@@ -439,8 +439,9 @@ class DataSource(CloudInitPickleMixin, metaclass=abc.ABCMeta):
prev_cloud_id_file = os.path.realpath(cloud_id_file)
else:
prev_cloud_id_file = cloud_id_file

•    util.sym_link(f"{cloud_id_file}-{cloud_id}", cloud_id_file, force=True)
  

•    if prev_cloud_id_file != cloud_id_file:
  

•    new_cloud_id_file = f"{cloud_id_file}-{cloud_id}"
  

•    util.sym_link(new_cloud_id_file, cloud_id_file, force=True)
  

•    if prev_cloud_id_file != new_cloud_id_file:
         util.del_file(prev_cloud_id_file)
     write_json(json_sensitive_file, processed_data, mode=0o600)
     json_file = self.paths.get_runpath("instance_data")
  

[ubuntu-server-builder]

Launchpad user Alberto Contreras(aciba) wrote on 2023-02-22T16:52:33.051720+00:00

This bug is believed to be fixed in cloud-init in version 23.1. If this is still a problem for you, please make a comment and set the state back to New

Thank you.