[systemd-devel] systemd-networkd-wait-online: Wait for specific address family to be online

[Ernst Bammer]

Hi,
sorry to bring this up again, but maybe somebody is back from vacation
who can answer this? ;-)
Best regards, Ernst

On Sun, Jul 24, 2016 at 12:31 PM, Ernst Bammer <herr.ernst at gmail.com> wrote:
> Hi,
>
> I have a service that depends on a non-loopback IPv4 address to be
> available at start-up. My network configuration is done with networkd,
> it's very simple and basically just:
>
> [Match]
> Name=eth*
> [Network]
> DHCP=v4
>
> I've added the following to my service:
>
> [Unit]
> Requires=network-online.target
> After=network-online.target
>
> Unfortunately, there is no IPv4 address when the service tries to
> start (and then crashes).
> For debugging purposes, I added this to [Service]:
>
> ExecStartPre=/bin/sh -c "/bin/cat /run/systemd/netif/links/*"
> ExecStartPre=/bin/sh -c "/bin/cat /run/systemd/netif/leases/*"
>
> On reboot, I see this in the journal:
>
> Jul 24 11:41:59 myhost sh[492]: # This is private data. Do not parse.
> Jul 24 11:41:59 myhost sh[492]: ADMIN_STATE=configured
> Jul 24 11:41:59 myhost sh[492]: OPER_STATE=degraded
> Jul 24 11:41:59 myhost sh[492]: FLAGS=69699
> Jul 24 11:42:00 myhost sh[529]: /bin/cat: /run/systemd/netif/leases/*:
> No such file or directory
> Jul 24 11:42:00 myhost systemd[1]: test.service: control process
> exited, code=exited status=1
> Jul 24 11:42:00 myhost systemd[1]: Failed to start Test.
> Jul 24 11:42:00 myhost systemd[1]: Unit test.service entered failed state.
>
> I suspect the problem might be that the network interface also gets a
> link-local IPv6 address, and thus systemd-networkd-wait-online
> immediately returns. If I disable IPv6 on my system (by blacklisting
> the ipv6 module), it works as expected (s-n-w-o waiting for DHCPV4
> address).
>
> Is there a way to get s-n-w-o to wait for an address family (in my
> case IPv4) to be available? Or is there any other workaround?
>
> FWIW, I'm using Debian 8 Jessie (systemd version 215).
>
> Thank you!
> Ernst