[Bug 1771236] Re: forced use of systemd-networkd interferes with ifupdown in 18.04

[Brandon Applegate]

Sigh.

After I push my /etc/network/interfaces from ansible (not the stub one I
previously posted) - "something" is re-reading it and applying settings.
This never happened in 16.04 until an ifup/ifdown, service restart or
reboot (which is what I expect and need).  Not quite sure how to find
the culprit.  But this is breaking my ansible flow in the middle of the
playbook as I lose the network config that Vmware put in.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to ifupdown in Ubuntu.
https://bugs.launchpad.net/bugs/1771236

Title:
  forced use of systemd-networkd interferes with ifupdown in 18.04

Status in ifupdown package in Ubuntu:
  Incomplete
Status in systemd package in Ubuntu:
  Incomplete

Bug description:
  For several reasons, we are not able to use netplan nor systemd-
  networkd due to legacy applications that expect ifupdown's pre-up and
  post-up script mechanism.  The documentation around 18.04's
  (premature, I feel) wholesale adoption of netplan claims that one can
  revert to old behaviour by merely installing ifupdown (amongst
  assertions that netplan will never offer a mechanism for configuring
  pre-up and post-up actions even for network managers that support
  them).

  However when ifupdown is installed, systemd-networkd still tries to
  manage interfaces.  If you 'systemctl disable systemd-networkd', upon
  next reboot it is automatically re-enabled.  We tried disabling any
  systemd units even remotely related to networking and yet systemd-
  networkd still runs.  If it hasn't been configured, it tries to DHCP.
  On networks that don't provide DHCP this results in a stupendously
  long stall during boot.  Currently it appears to be impossible to tell
  systemd-networkd not to run in a clean manner that won't get reverted
  on package upgrades.

  I sincerely hope this is is a bug/oversight and not intentional.  We
  need to be able to disable systemd-networkd properly.

  Thanks

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/1771236/+subscriptions