[Bug 1983419] Re: cloud-init is always upgrading the kernel to latest

[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: subiquity (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1983419

Title:
  cloud-init is always upgrading the kernel to latest

Status in subiquity package in Ubuntu:
  Confirmed

Bug description:
  Hi !

  I've been using cloud-init to build Ubuntu 20.04 VM Images with Packer
  from a the ISO file
  https://releases.ubuntu.com/20.04/ubuntu-20.04.4-live-server-amd64.iso
  that has been created couple of months ago, in February.

  When starting an Ubuntu Server using this ISO file directly, we can
  see that the Kernel version is the kernel of February, which makes
  sense since that's the date of the ISO build.

  Last month, in July, a bug has been detected in the latest version of
  the Linux kernel, version 5.4.0-122.

  Due to this kernel bug, I have been trying to build an Ubuntu Image
  that would not use the latest kernel. My goal was then to later
  upgrade the kernel up to the last known working kernel, which is
  version 5.4.0-121.

  Sadly, it seems like cloud-init is ignoring the option 'refresh-
  installer' and the Image that is built is directly installing the
  latest version of the kernel, which is the one that contains the bug.

  
  I tried the following approach to disable the automatic upgrade of the kernel:

  Test 1:
  #cloud-config
  autoinstall:
    refresh-installer:
      update: no

  Test 2:
  #cloud-config
  autoinstall:
    early-commands:
      - apt-mark hold linux-generic linux-image-generic linux-header-generic

  Test 3:
  #cloud-config
  autoinstall:
    early-commands:
      - echo "Unattended-Upgrade::Package-Blacklist {" > /target/etc/apt/apt.conf.d/50unattended-upgrades
      - echo "\"linux-generic\";" >> /target/etc/apt/apt.conf.d/50unattended-upgrades
      - echo "\"linux-image-generic\";" >> /target/etc/apt/apt.conf.d/50unattended-upgrades
      - echo "\"linux-headers-generic\";" >> /target/etc/apt/apt.conf.d/50unattended-upgrades
      - echo "};" >> /target/etc/apt/apt.conf.d/50unattended-upgrades

  In Test 1 and 2, the kernel is anyway upgraded to version 5.4.0-122.

  In test 3, the image fail to be built.

  I believe there should be a way to avoid automatically upgrading the
  kernel to the latest version when building the image, but for some
  reason I have not been able to identify how to do that.

  Any ideas ?

  Thanks

  Thomas

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