[systemd-devel] systemd-networkd doesn't delete netdev when parent interface is deleted

[Susant Sahani]

On 08/21/2015 03:44 AM, hello at andreborie.name wrote:
> Hello,
>
> I'm trying to use systemd-networkd to manage a "sit" tunnel and I've hit
> problem. My internet connection is provided by "ppp0" which isn't
> directly managed by networkd and can come and go at anytime. I have a
> .network file with "[Match] Name=ppp0" that works as expected and
> correctly configures DNS and forwarding on that interface. I then added
> a .netdev file for the tunnel and referenced it using the "[Network]
> Tunnel=..." directive in ppp0's .network file. That works as expected
> and the tunnel is configured with ppp0 as its device :
>
>      heipv6: ipv6/ip  remote 216.66.84.42  local any  dev ppp0  ttl 255
> 6rd-prefix 2002::/16
>
> The problem happens when the ppp0 interface goes down. The tunnel netdev
> remains but references a non-existing interface "ifXX" and is obviously
> not operational anymore :
>
>      heipv6: ipv6/ip  remote 216.66.84.42  local any  dev if34  ttl 255
> 6rd-prefix 2002::/16
>
> Worse, once the ppp0 interface comes back up, that netdev remains
> untouched and still points to the non-existing interface. Restarting
> systemd-networkd doesn't have any effect either. Only deleting the
> tunnel with "ip tunnel del" and then either restarting systemd-networkd
> or pppd (to recreate an ppp0 interface) causes systemd-networkd to
> create a new tunnel correctly referencing the new ppp0.
>
> According to the manual for systemd.netdev, this is expected behavior :
>
>      If a netdev with the specified name already exists, networkd will
> use that as-is rather than create its own. Note that the settings of the
> pre-existing netdev will not be changed by networkd.
>
> However, in my case it's clearly undesirable behavior and I'd like to
> know what should I do to get this working. Here are the relevant
> configuration files :
>
> # ppp.network
>
>      [Match]
>      Name=ppp0
>
>      [Network]
>      DHCP=no
>      Tunnel=heipv6
>
> # he.netdev
>
>      [NetDev]
>      Name=heipv6
>      Kind=sit
>
>      [Tunnel]
>      Remote=216.66.84.42
>
> Thanks.
>
> TLDR: I need to make systemd-networkd override some settings of an
> existing netdev, or delete a netdev after its parent device has
> disappeared.

yes right now we don't support deletion dynamically. Probably we would 
do that in future doing via networkctl.
Susant