[systemd-devel] Netconsole NG

Tue Apr 8 05:10:14 PDT 2014

On 08.04.2014 04:03, poma wrote:
> On 07.04.2014 19:55, Zbigniew Jędrzejewski-Szmek wrote:
>> On Mon, Apr 07, 2014 at 05:34:10PM +0200, Lukáš Nykrýn wrote:
>>> The reason why this was not rewritten a long time ago is that the
>>> initscript tries to figure some of those values by itself (for
>>> example the MAC address). But yes, we need to do something with
>>> netconsole. It is a blocker for my initscripts evil plan.
>> Doesn't netconsole figure out most of those settings by itself, and
>> others default to sensible values, so if the network card is up
>> and has an address configured, only the device and target ip must be given?
>>
>>> Dne 6.4.2014 17:59, poma napsal(a):
>>>>
>>>> /etc/sysconfig/netconsole:
>>>> # This is the EnvironmentFile for the netconsole service. Starting this
>>>> # service enables the capture of dmesg output on a destination machine.
>>>>
>>>> # Source port
>>>> SRC_PORT=12345
>> This should default to empty... Kernel will pick something.
>>
>>>>
>>>> # Source IP address
>>>> SRC_IP=192.168.1.2
>> This should default to empty... Kernel will use configured address,
>> since we order after network.target anyway.
>>
>>>> # Source network device
>>>> SRC_DEV=enp1s2
>> Maybe this can be made into a instance argument?
>>
>>>> # Destination port
>>>> DST_PORT=12345
>> I think this should default to 514/syslog, and can be left unset.
>>
>>>> # Destination IP address
>>>> DST_IP=192.168.1.1
>>>>
>>>> # Destination ethernet address
>>>> DST_EHA=00:11:22:33:44:55
>> This should default to unset. The kernel will query it if not set.
>>
>>>> /usr/lib/systemd/system/netconsole.service:
>>>> [Unit]
>>>> Description=Adds the netconsole module with the configured parameters
>>>> After=network.target
>>>>
>>>> [Service]
>>>> EnvironmentFile=/etc/sysconfig/netconsole
>> This is Fedora/RH specific. But I don't know what the proper path should
>> be, so maybe this is OK for now.
>>
>>>> Type=simple
>> This is the default... No need to specify.
>>
>>>> RemainAfterExit=yes
>>>> ExecStart=/usr/sbin/modprobe netconsole
>> This should be /sbin/modprobe for compatibility with split root.
>>
>>>> netconsole=${SRC_PORT}@${SRC_IP}/${SRC_DEV},${DST_PORT}@${DST_IP}/${DST_EHA}
>>>> ExecStop=/usr/sbin/modprobe -r netconsole
>> Ditto.
>>
>>>>
>>>> [Install]
>>>> WantedBy=multi-user.target
>> That's a really late... But I don't see a better place unfortunately.
>>
>>>> The original SysV netconsole service with related config - still in use,
>>>> https://git.fedorahosted.org/cgit/initscripts.git/plain/rc.d/init.d/netconsole
>>>> https://git.fedorahosted.org/cgit/initscripts.git/plain/sysconfig/netconsole
>>>>
>>>> Feel free to comment.
>> Looks like an improvement on status quo.
>>
>> Zbyszek
>>
> 
> Shall we still leave something for users to configure.
> Thanks for your review.
> 

$ cat /usr/lib/systemd/system/netconsole-zbyszek.service
[Unit]
Description=Adds the netconsole module with the configured parameters
After=network.target

[Service]
EnvironmentFile=/etc/sysconfig/netconsole-zbyszek
RemainAfterExit=yes
ExecStart=/sbin/modprobe netconsole netconsole=@/${SRC_DEV},@${DST_IP}/
ExecStop=/sbin/modprobe -r netconsole

[Install]
WantedBy=multi-user.target

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

$ cat /etc/sysconfig/netconsole-zbyszek
# This is the EnvironmentFile for the netconsole service. Starting this
# service enables the capture of dmesg output on a destination machine.

# Source network device
SRC_DEV=enp1s2

# Destination IP address
DST_IP=192.168.1.1

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

$ dmesg | grep netcon
[   24.361611] netpoll: netconsole: local port 6665
[   24.361764] netpoll: netconsole: local IPv4 address 0.0.0.0
[   24.361893] netpoll: netconsole: interface 'enp1s2'
[   24.362061] netpoll: netconsole: remote port 6666
[   24.362344] netpoll: netconsole: remote IPv4 address 192.168.1.1
[   24.362635] netpoll: netconsole: remote ethernet address
ff:ff:ff:ff:ff:ff
[   24.362909] netpoll: netconsole: no IP address for enp1s2, aborting
[   24.363186] netconsole: cleaning up

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This turns out to be a bare minimum, i.e.
# modprobe netconsole netconsole=@/enp1s2, at 192.168.1.1/
but that is also squeeze breeze ...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

$ cat /usr/lib/systemd/system/netconsole-poma.service
[Unit]
Description=Adds the netconsole module with the configured parameters
After=network.target

[Service]
EnvironmentFile=/etc/sysconfig/netconsole-poma
RemainAfterExit=yes
ExecStart=/sbin/modprobe netconsole
netconsole=@${SRC_IP}/${SRC_DEV},@${DST_IP}/
ExecStop=/sbin/modprobe -r netconsole

[Install]
WantedBy=multi-user.target

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

$ cat /etc/sysconfig/netconsole-poma
# This is the EnvironmentFile for the netconsole service. Starting this
# service enables the capture of dmesg output on a destination machine.

# Source IP address
SRC_IP=192.168.1.2

# Source network device
SRC_DEV=enp1s2

# Destination IP address
DST_IP=192.168.1.1

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

$ dmesg | grep netcon
[   23.156730] netpoll: netconsole: local port 6665
[   23.156735] netpoll: netconsole: local IPv4 address 192.168.1.2
[   23.156736] netpoll: netconsole: interface 'enp1s2'
[   23.156737] netpoll: netconsole: remote port 6666
[   23.156738] netpoll: netconsole: remote IPv4 address 192.168.1.1
[   23.156739] netpoll: netconsole: remote ethernet address
ff:ff:ff:ff:ff:ff
[   23.156742] netpoll: netconsole: device enp1s2 not up yet, forcing it
[   25.539701] console [netcon0] enabled
[   25.539720] netconsole: network logging started

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
And this turns out to be a true bare minimum, i.e.
# modprobe netconsole netconsole=@192.168.1.2/enp1s2, at 192.168.1.1/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

poma