Re: [systemd-devel] systemd-networkd-wait-online should know if there is anything to wait for

[Colin Guthrie]

Dimitri John Ledkov wrote on 26/03/18 11:34:
> Hello,
> 
> When systemd-networkd-wait-online was originally introduced, it was
> the only tool that correctly waited and blocked the boot, until after
> networking is configured.
> 
> These days, however, all/most network configurations tools ship
> appropriate wait-online integration. E.g. there is network-manager
> wait online service and ifupdown wait online, on Debian/Ubuntu.
> 
> These other helpers, seem to be slightly smarter than
> systemd-networkd-wait-online. Specifically, all other helpers exit
> straight away, if they have no devices configured / managed. Whilst
> systemd-networkd-wait-online, doesn't appear to know if it expects any
> devices / can manage any devices. Ideally, if no devices are
> configured / no devices match .network files, maybe it should exit
> straight away? Or for example, do so if no devices are found in
> "configuring/pending/not yet processed by udev".
> 
> (code wise, it is to change one_ready to true by default, and only
> continue blocking the, if there is anything pending configuration).
> 
> I'm considering doing this by default, or for-example, doing it if
> there are no /run/systemd/network/*.network
> /etc/systemd/network/*.network files.
> 
> The use cases when it matters:
> 
> - installer ISO booted without any NICs attached
> (or NICs require special drivers / firmware loaded etc)
> 
> - cloud-image booted and cloud-init failed to find network-config and
> generate networkd stanzas

But how do you differentiate a device which is not present vs. one which
is slow to appear?

If the system isn't online then surely any dependant units don't need to
be started anyway. If the system requires being online to operate
properly then all this behaviour is correct.

If you don't use systemd-networkd then you possibly don't want
systemd-networkd-wait-online either and thus it can be happily disabled.

So I don't really appreciate why this is an issue. Unless, you're trying
to use a kind of hybrid environment (e.g. using networkd for wired
networks (perhaps USB dongles) and NetworkManager for wifi and you'd
want networkd-wait-online to be a no-op when the USB dongle is not there?)

I guess it's possible to know if networkd is configured to not manage
any devices *at all*, but perhaps there isn't much point in enabling the
networkd-wait-online service at all in that case anyway?

Struggling to understand the "why" question here, but could easily be
missing something! :-)

Col



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[systemd-devel] systemd-networkd-wait-online should know if there is anything to wait for

[Dimitri John Ledkov]

Hello,

When systemd-networkd-wait-online was originally introduced, it was
the only tool that correctly waited and blocked the boot, until after
networking is configured.

These days, however, all/most network configurations tools ship
appropriate wait-online integration. E.g. there is network-manager
wait online service and ifupdown wait online, on Debian/Ubuntu.

These other helpers, seem to be slightly smarter than
systemd-networkd-wait-online. Specifically, all other helpers exit
straight away, if they have no devices configured / managed. Whilst
systemd-networkd-wait-online, doesn't appear to know if it expects any
devices / can manage any devices. Ideally, if no devices are
configured / no devices match .network files, maybe it should exit
straight away? Or for example, do so if no devices are found in
"configuring/pending/not yet processed by udev".

(code wise, it is to change one_ready to true by default, and only
continue blocking the, if there is anything pending configuration).

I'm considering doing this by default, or for-example, doing it if
there are no /run/systemd/network/*.network
/etc/systemd/network/*.network files.

The use cases when it matters:

- installer ISO booted without any NICs attached
(or NICs require special drivers / firmware loaded etc)

- cloud-image booted and cloud-init failed to find network-config and
generate networkd stanzas

-- 
Regards,

Dimitri.
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Re: [systemd-devel] systemd-networkd-wait-online

[Lennart Poettering]

On Fr, 08.12.17 20:54, Johannes Ernst (johannes.er...@gmail.com) wrote:

> Thanks. I’m not surprised that work remains ...
> 
> Related question: systemd-networkd-wait-online.target seems to
> assume that once the network is online, it stays that way. I’d like
> to also take action when it goes down, and again when it comes back
> up. Any pointers how to best go about this? Is there an inverse of
> the systemd-networkd-wait-online executable?

No, targets are not supposed to fully track system state. If you want
to track network up/down cycles use the rtnetlink API. Sorry.

Lennart

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Re: [systemd-devel] systemd-networkd-wait-online

[Johannes Ernst]

Thanks. I’m not surprised that work remains ...

Related question: systemd-networkd-wait-online.target seems to assume that once 
the network is online, it stays that way. I’d like to also take action when it 
goes down, and again when it comes back up. Any pointers how to best go about 
this? Is there an inverse of the systemd-networkd-wait-online executable?

Thanks,



Johannes.

> On Dec 6, 2017, at 3:30, Lennart Poettering  wrote:
> 
> On Di, 05.12.17 12:21, Johannes Ernst (johannes.er...@gmail.com) wrote:
> 
> See the discussion on
> https://github.com/systemd/systemd/issues/7478#issuecomment-348508263
> regarding this kind of hardware.
> 
> Lennart
> 
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Re: [systemd-devel] systemd-networkd-wait-online

[Lennart Poettering]

On Di, 05.12.17 12:21, Johannes Ernst (johannes.er...@gmail.com) wrote:

See the discussion on
https://github.com/systemd/systemd/issues/7478#issuecomment-348508263
regarding this kind of hardware.

Lennart

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[systemd-devel] systemd-networkd-wait-online

[Johannes Ernst]

I’m running systemd 235.38 on an ARM64 device called the EspressoBin [1]. The 
EspressoBin board has an on-board Ethernet switch, which I configure with 
systemd-networkd (configuration is below). The device is intended as a home 
router that runs IPv4 masquerading, local DNS server etc.

I’m attempting to take action when the wan interface has a network connection 
to the upstream ISP. I discovered 
/usr/lib/systemd/systemd-networkd-wait-online, which behaves as follows:

% systemd-networkd-wait-online -i wan
Exactly what I would expect — once I connect upstream Ethernet, it prints 
"ignoring: lan0, lan1, eth0, lo” and returns true

% systemd-networkd-wait-online —ignore lan0 —ignore lan1
Same as first

% systemd-networkd-wait-online
“Hangs”

% systemd-networkd-wait-online -i lan0
“Hangs”

The way I read the man page [2] systemd-networkd-wait-online is supposed to 
return with true, even if only the wan interface is connected and the other two 
ports are configured (but not connected). Is my understanding correct? Or do 
all three ports need to be connected?

Thanks,



Johannes.



Configuration:

::
49-ubos-eth0.network
::
[Match]
Name=eth0

[Network]

::
50-ubos-lan0.network
::
[Match]
Name=lan0

[Network]
Address=192.168.140.1
DNS=192.168.140.1
IPForward=yes
BindCarrier=eth0

::
50-ubos-lan1.network
::
[Match]
Name=lan1

[Network]
Address=192.168.141.1
DNS=192.168.141.1
IPForward=yes
BindCarrier=eth0

::
50-ubos-wan.network
::
[Match]
Name=wan

[Network]
DHCP=yes
IPForward=yes
BindCarrier=eth0






[1] https://espressobin.net/
[2] 
https://www.freedesktop.org/software/systemd/man/systemd-networkd-wait-online.service.html


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

[J Decker]

goes back to 'can we have a configurable script to run when DHCP assigns
the address?'
Surely it can't be that hard to read a config line, save it, and later
execute a script


On Tue, Sep 6, 2016 at 1:54 PM, Ernst Bammer  wrote:

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

[Ernst Bammer]

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
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Re: [systemd-devel] systemd-networkd-wait-online and network.target

[Alexey Shabalin]

2014-06-25 14:12 GMT+04:00 Michael Olbrich m.olbr...@pengutronix.de:
 Hi,

 Commit 58e027023b47b32e42cf93dd4a629b869ee1ef25 'units: order
 network-online.target after network.target' added Before=network.target
 dependency to systemd-networkd-wait-online.service. Is that correct? If I
 understand the documentation correctly, then network.target should not be
 delayed. Maybe this was supposed to be Afternetwork.target?

 Regards,
 Michael

Can you some ask to NetworkManager upstream about
NetworkManager-wait-online.service ?


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Re: [systemd-devel] systemd-networkd-wait-online and network.target

[Lennart Poettering]

On Sun, 29.06.14 23:58, Tom Gundersen (t...@jklm.no) wrote:

 
 On Wed, Jun 25, 2014 at 12:12 PM, Michael Olbrich
 m.olbr...@pengutronix.de wrote:
  Commit 58e027023b47b32e42cf93dd4a629b869ee1ef25 'units: order
  network-online.target after network.target' added Before=network.target
  dependency to systemd-networkd-wait-online.service. Is that correct? If I
  understand the documentation correctly, then network.target should not be
  delayed. Maybe this was supposed to be Afternetwork.target?
 
 Looks like a bug to me. Reverted that hunk.

You forgot to push?

Lennart

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Re: [systemd-devel] systemd-networkd-wait-online and network.target

[Tom Gundersen]

On Mon, Jun 30, 2014 at 1:04 PM, Lennart Poettering
lenn...@poettering.net wrote:
 On Sun, 29.06.14 23:58, Tom Gundersen (t...@jklm.no) wrote:


 On Wed, Jun 25, 2014 at 12:12 PM, Michael Olbrich
 m.olbr...@pengutronix.de wrote:
  Commit 58e027023b47b32e42cf93dd4a629b869ee1ef25 'units: order
  network-online.target after network.target' added Before=network.target
  dependency to systemd-networkd-wait-online.service. Is that correct? If I
  understand the documentation correctly, then network.target should not be
  delayed. Maybe this was supposed to be Afternetwork.target?

 Looks like a bug to me. Reverted that hunk.

 You forgot to push?


Indeed. Done.

-t
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Re: [systemd-devel] systemd-networkd-wait-online and network.target

[Tom Gundersen]

On Wed, Jun 25, 2014 at 12:12 PM, Michael Olbrich
m.olbr...@pengutronix.de wrote:
 Commit 58e027023b47b32e42cf93dd4a629b869ee1ef25 'units: order
 network-online.target after network.target' added Before=network.target
 dependency to systemd-networkd-wait-online.service. Is that correct? If I
 understand the documentation correctly, then network.target should not be
 delayed. Maybe this was supposed to be Afternetwork.target?

Looks like a bug to me. Reverted that hunk.

Cheers,

Tom
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[systemd-devel] systemd-networkd-wait-online and network.target

[Michael Olbrich]

Hi,

Commit 58e027023b47b32e42cf93dd4a629b869ee1ef25 'units: order
network-online.target after network.target' added Before=network.target
dependency to systemd-networkd-wait-online.service. Is that correct? If I
understand the documentation correctly, then network.target should not be
delayed. Maybe this was supposed to be Afternetwork.target?

Regards,
Michael

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