[Bug 1734167] Re: DNS doesn't work in no-cloud as launched by ubuntu

[James Falcon]

Tracked in Github Issues as https://github.com/canonical/cloud-
init/issues/3065

** Bug watch added: github.com/canonical/cloud-init/issues #3065
   https://github.com/canonical/cloud-init/issues/3065

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https://bugs.launchpad.net/bugs/1734167

Title:
  DNS doesn't work in no-cloud as launched by ubuntu

Status in cloud-init:
  Fix Released
Status in cloud-init package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Zesty:
  Fix Released
Status in systemd source package in Zesty:
  Fix Released
Status in cloud-init source package in Artful:
  Won't Fix
Status in systemd source package in Artful:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released

Bug description:
  [Impact]

   * resolved does not start early enough in the boot-process preventing
  DNS resolution to be operational during early boot, for example as
  required by special early stages of cloud-init, resulting in failure
  to boot / provision the instance fully.

  [Test Case]

   * Boot container or a VM with a nocloud-net data source, and a URL pointing to the datasource as explained below
   * Observe that boot completes and provisioning is successful
   * Check that there are no dns-resolution errors in the cloud-init log / boot log

  [Regression Potential]

   * starting resolved earlier may prevent it from connecting to dbus,
  and may require a restart later on when re-triggered over dbus. This
  is on artful only, as in bionic resolved has gained ability to
  reconnected to dbus post-start. Backporting that, however, is too
  large for an SRU as it requires sd-bus changes.

  [Other Info]
   
   * Original bug report.

  I use no-cloud to test the kernel in CI (I am maintainer of the bcache
  subsystem), and have been running it successfully under 16.04 cloud
  images from qemu, using a qemu command that includes:

  -smbios "type=1,serial=ds=nocloud-
  net;s=https://raw.githubusercontent.com/mlyle/mlyle/master/cloud-
  metadata/linuxtst/"

  As documented here:

  http://cloudinit.readthedocs.io/en/latest/topics/datasources/nocloud.html

  Under the new 17.10 cloud images, this doesn't work: the network comes
  up, but name resolution doesn't work-- /etc/resolv.conf is a symlink
  to a nonexistent file at this point of the boot and systemd-resolved
  is not running.  When I manually hack /etc/resolv.conf in the cloud
  image to point to 4.2.2.1 it works fine.

  I don't know if nameservice not working is by design, but it seems
  like it should work.  The documentation states:

  "With ds=nocloud-net, the seedfrom value must start with http://,
  https:// or ftp://"

  And https is not going to work for a raw IP address.

  Related bugs:
   * bug 1734939: #include fails silently.

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