Dear Maintainer,

I'm not sure if this bug should be filed against ifupdown or ifupdown2.
This issue only seems to affect current versions of these packages
in buster, I haven't encountered this in stretch.

When installing ifupdown2, apt will remove ifupdown before proceeding with
installation of ifupdown2 as the two cannot co-exist on the same system.

The problem seems to be that, following removal of ifupdown, the networking
service is stopped, and the host loses all connectivity. This behaviour is
potentially debilitating, especially when the task is performed via SSH
or via configuration management software which depends on the host
being reachable over the network to operate.

When issuing the command to install ifupdown2 over SSH the issue can be
quite easily worked around by restarting the networking service immediately
after ifupdown2 is installed:
  apt-get install ifupdown2 && systemctl restart networking

However, there seems to be no simple solution when using configuration
management (like ansible) to install ifupdown2. The relevant tasks will
hang forever upon ifupdown2 installation.

Is this deliberate? Any chance you can reconsider the actions taken
upon uninstallation of ifupdown? Thank you.

Best regards,
George Diamantopoulos

Hello,

Any chance this will get looked into before buster is released? Thanks!

BR,
George

This is a bit tricky. Especially with systemd, there is no easy way to
say "please stop this service but don't execute its ExecStop command".
Also, properly shutting down the network will be nicer for ifupdown2,
because if ifupdown doesn't shut down cleanly, ifupdown2 might not start
in an orderly way.

For provisioning systems like ansible, puppet etc., I recommend that you
set it up to push a script to the node that basically executes the
equivalent of "apt-get install ifupdown2 && systemctl restart
networking" using nohup or something else to make it not fail if the
network itself is down.

On the other hand, if ifupdown2 would automatically start the network at
install time, you wouldn't need the systemctl command to restart the
network. Maybe that is enough to fix this issue? I'm Cc'ing the
maintainer of ifupdown2.

your configuration file is compatible with ifupdown2. We should support
most of ifupdown syntax though but you may loose connectivity.
Instead you may consider running ifreload: apt-get install ifupdown2 &&
ifreload -a

This is a possibility that i'm considering as well.