[PATCH] dracut-module-setup: Make kdump shell honour and check for PEERDNS

[Minfei Huang]

On 09/12/2014 12:03 AM, Vivek Goyal wrote:
> On Thu, Sep 11, 2014 at 01:29:47PM +0800, Minfei Huang wrote:
>> Resolves: rhbz805307
>
> This is RHEL bug number. Please don't specify it when you are posting
> patches for inclusion in fedora.
>
>
>>
>> It is useless to configurate the /etc/dhclient.conf to valid in the
>> second kernel, when get network config by dhcp. Using the following
>> dhclient configuration, the kernel will not override the
>> configuration getting from the dhcp server in the file /etc/resolv.conf.
>>
>> supersede domain-name "machine.test.group";
>> supersede domain-name-servers 10.125.97.171, 10.126.98.43, 10.125.97.176;
>>
>> According to the condition, we should determine to modify the
>> /etc/dhclient.conf or not. If set the PEERDNS="no" in the configuration of
>> /etc/sysconfig/network-scripts/ifcfg-$net_dev, the dhclient configuration
>> will override the search domain and dns servers received from dhcp server.
>
> I think this changelog description needs to be improved. I can't
> understand what's the problem. So changelog should describe few
> things very cleary.
>
> - What's the problem.
> - Why that problem is happening in current code.
> - How your patch fixes that problem.
>
> I think you have focussed a lot on 3 part but first two things are
> missing from changelog.
>
> Thanks
> Vivek
>

The network will get the DNS from the /etc/resolv.conf. The config 
resolv.conf generates by the dhcp server, also we can modify it 
manually. But the configuration which we add manually to the resolv.conf 
will be lost when the network restart.

So in order to solve this problem, we can add the option of PEERDNS=no 
to the ifcfg-{*}, the resolv.conf file will not be changed again by the 
dhcp server.

The dracut will use own default configuration (in dracut directory) to 
configure the network, whatever the custom modify the configuration in 
/etc/dhclient.conf.
I send a patch to the dracut community. The patch can only do one thing 
that it will append the valid content from /etc/dhclient.conf to 
${initdir}/etc/dhclient.conf.

We(Dave and me) think that the configuratin need to be valid in the 
second kernel, if the custom set the own configuration to the 
dhclient.conf.
So we should ignore the option of PEERDNS, even if set the option 
PEERDNS=no in ifcfg-*.
And the kdump will have no change for this BUG.

>>
>> Signed-off-by: Minfei Huang <mhuang at redhat.com>
>> ---
>>   dracut-module-setup.sh | 12 ++++++++++++
>>   1 file changed, 12 insertions(+)
>>
>> diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
>> index 02a0557..008e560 100755
>> --- a/dracut-module-setup.sh
>> +++ b/dracut-module-setup.sh
>> @@ -66,6 +66,16 @@ kdump_setup_dns() {
>>       [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
>>   }
>>
>> +kdump_setup_dhclient() {
>> +    _dhclient_file="/etc/dhclient.conf"
>> +    [ ! -e $_dhclient_file ] && return
>> +
>> +    . /etc/sysconfig/network-scripts/ifcfg-$1
>> +    if [ "x""$PEERDNS" = "xno" ] || [ "x""$PEERDNS" = "xNO" ]; then
>> +        cat $_dhclient_file | grep ^supersede >> ${initdir}/$_dhclient_file
>> +    fi
>> +}
>> +
>>   #$1: netdev name
>>   #$2: srcaddr
>>   #if it use static ip echo it, or echo null
>> @@ -252,6 +262,8 @@ kdump_setup_netdev() {
>>       fi
>>
>>       kdump_setup_dns "$_netdev"
>> +
>> +    kdump_setup_dhclient "$_netdev"
>>   }
>>
>>   #Function:kdump_install_net
>> --
>> 1.8.3.1
>>
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-- 
Minfei