[Bug 1490796] Re: [SRU] cloud-init must check/format Azure ephemeral disks each boot

[Dan Watkins]

** Description changed:

- Ubuntu 14.04.3 (20150805) on Azure with cloud-init package
- 0.7.5-0ubuntu1.8.
+ 
+ [Impact]
+ Sometimes when rebooting an instance in Azure, a different ephemeral disk will be presented. Azure ephemeral disks are presented as NTFS disks, but we reformat them to ext4.  With the last cloud-init upload, we shifted to using /dev/disk symlinks to mount these disks (in case they are not presented as the same physical device).  Unfortunately, the code that determines if we have a new ephemeral disk was not updated to handle symlinks, so never detects a new disk.
+ 
+ [Test Case]
+ 1) Boot an Azure instance and install the new cloud-init.
+ 2) Change the size of the instance using the Azure web interface (as this near-guarantees that the ephemeral disk will be replaced with a new one). This will reboot the instance.
+ 3) Once the instance is rebooted, SSH in and confirm that:
+  a) An ext4 ephemeral disk is mounted at /mnt, and
+  b) cloud-init.log indicates that a fabric formatted ephemeral disk was found on this boot.
+ 
+ [Regression Potential]
+ Limited; two LOCs change, to dereference symlinks instead of using paths verbatim.
+ 
+ [Original Report]
+ Ubuntu 14.04.3 (20150805) on Azure with cloud-init package 0.7.5-0ubuntu1.8.
  
  On Azure cloud-init prepares the ephemeral device as ext4 for the first
  boot.  However, if the VM is ever moved to another Host for any reason,
  then a new ephemeral disk might be provided to the VM.  This ephemeral
  disk is NTFS formatted, so for subsequent reboots cloud-init must detect
  and reformat the new disk as ext4.  However, with cloud-init
  0.7.5-0ubuntu1.8 subsequent boots may result in fuse mounted NTFS file
  system.
  
  This issue occurred in earlier versions of cloud-init, but was fixed
  with bug 1292648 (https://bugs.launchpad.net/ubuntu/+source/cloud-
  init/+bug/1292648).  So this appears to be a regression.
  
  Repro:
-   - Create an Ubuntu 14.04.3 VM on Azure
-   - Resize the VM to a larger size (this typically moves the VM)
-   - Log in and run 'blkid' to show an ntfs formatted ephemeral disk:
+   - Create an Ubuntu 14.04.3 VM on Azure
+   - Resize the VM to a larger size (this typically moves the VM)
+   - Log in and run 'blkid' to show an ntfs formatted ephemeral disk:
  
-     # blkid
-     /dev/sdb1: LABEL="Temporary Storage" UUID="A43C43DD3C43A95E" TYPE="ntfs"
- 
+     # blkid
+     /dev/sdb1: LABEL="Temporary Storage" UUID="A43C43DD3C43A95E" TYPE="ntfs"
  
  Expected results:
-   - After resizing the ephemeral disk should be formatted as ext4.
+   - After resizing the ephemeral disk should be formatted as ext4.

-- 
You received this bug notification because you are a member of Ubuntu
Server Team, which is subscribed to cloud-init in Ubuntu.
https://bugs.launchpad.net/bugs/1490796

Title:
  [SRU] cloud-init must check/format Azure ephemeral disks each boot

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1490796/+subscriptions