[systemd-devel] Masking .network files

[Tom Gundersen]

On Sat, Apr 5, 2014 at 12:43 AM, Leonid Isaev <lisaev at umail.iu.edu> wrote:
>         I seem to have a strange issue with the way networkd processes its
> configuration files. The machine is actually a systemd-nspawn container with
> a static IP address, so I had to mask the default 80-container-host0.network
> and create a custom config. Both real and virtual machines are up-to-date
> archlinux [testing] installations.

So the best way to do this is to name your custom config file either
the same as what you are overriding (if the overridden file should
anyway never be used, which is the case for what you describe), or
simply name it starting with a lower number. That way the first
matching file will be applied.

The 'masking' logic that you know from unit files does not really make
much sense for .network files (but maybe this is something we should
change...). Symlinks to /dev/null are just treated as empty .network
files, so their meaning is "no [Match] section", which matches
everything and "no [Network] section", which does nothing. I suppose
this may be used to express "ignore any subsequent .network files",
but I doubt that is a particularly useful thing to do.

> -----
> $ file /{etc,usr/lib}/systemd/network/80-container-host0.network
> /etc/systemd/network/80-container-host0.network: symbolic link to `/dev/null'
> /usr/lib/systemd/network/80-container-host0.network: ASCII text
> $ cat /etc/systemd/network/eth.network
> [Match]
> Name=host0
>
> [Network]
> Address=10.137.0.2/24
> Gateway=10.137.0.1
>
> [DHCPv4]
> UseDNS=false
> -----
>
> However, this new .network file is never picked up by systemd-networkd (it
> does provide a working network setup if the host0 interface is renamed). Here
> is the debug output:
>
> -----
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: timestamp of
> '/etc/systemd/network' changed
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: timestamp of
> '/run/systemd/network' changed
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: Skipping overridden
> file: /usr/lib/systemd/network/80-container-host0.network.
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: Configuration
> file /etc/systemd/network/80-container-host0.network is marked world-writable.
> Please remove world writability permission bits. Proceeding anyway.
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: host0: found matching
> network '/etc/systemd/network/80-container-host0.network'
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: host0: requesting link
> status
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: host0: bringing link up
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: host0: link configured
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: host0: link (with ifindex
> 22) added
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: lo: found matching network
> '/etc/systemd/network/80-container-host0.network'
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: lo: requesting link status
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: lo: bringing link up
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: lo: link configured
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: lo: link (with ifindex 1)
> added
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: host0: MAC address:
> 36:9a:b1:98:ab:e1
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: host0: link status
> updated: 00000000 -> 0x00011043
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: host0: link is up
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: host0: carrier on
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: Sent message
> type=method_call sender=n/a destination=org.freedesktop.DBus object=/org/freedesktop/DBus interface=org.freedesktop.DBus member=Hello cookie=1 reply_cookie=0 error=n/a
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: Got message
> type=method_return sender=org.freedesktop.DBus destination=:1.8 object=n/a interface=n/a member=n/a cookie=1 reply_cookie=1 error=n/a
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: lo: link status updated:
> 00000000 -> 0x00010049
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: lo: link is up
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: lo: carrier on
> Apr 04 21:29:00 lxc_archtest systemd-networkd[128]: Got message type=signal
> sender=org.freedesktop.DBus destination=:1.8 object=/org/freedesktop/DBus interface=org.freedesktop.DBus member=NameAcquired cookie=2 reply_cookie=0 error=n/a
> Apr 04 21:29:02 lxc_archtest systemd-networkd[128]: Received SIGINT.
> Apr 04 21:29:02 lxc_archtest systemd-networkd[128]: Assertion
> 's->event->state != SD_EVENT_FINISHED' failed at src/libsystemd/sd-event/sd-event.c:1308, function sd_event_source_set_enabled(). Ignoring.
> Apr 04 21:29:02 lxc_archtest systemd-networkd[128]: Assertion
> 's->event->state != SD_EVENT_FINISHED' failed at src/libsystemd/sd-event/sd-event.c:1308, function sd_event_source_set_enabled(). Ignoring.
> Apr 04 21:29:02 lxc_archtest systemd-networkd[128]: Assertion
> 's->event->state != SD_EVENT_FINISHED' failed at
> src/libsystemd/sd-event/sd-event.c:1308, function sd_event_source_set_enabled(). Ignoring.
> -----
>
> I understand that the 1st matching configuration is applied but why does it
> concern overriden files? Also, why does a symlink to /dev/null match all
> interfaces (even loopback)?
>
> Thanks,
> --
> Leonid Isaev
> GnuPG key fingerprint: C0DF 20D0 C075 C3F1 E1BE  775A A7AE F6CB 164B 5A6D
>
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