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

[Minfei Huang]

Resolves: rhbz805307

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.

Signed-off-by: Minfei Huang 
---
 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

[Vivek Goyal]

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
> Signed-off-by: Minfei Huang
>
> 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
>
> kexec mailing list
> [e-mail]
> https://lists.fedoraproject.org/mailman/listinfo/kexec

[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
> >
> > 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
> >
> > kexec mailing list
> > [e-mail]
> > https://lists.fedoraproject.org/mailman/listinfo/kexec

[Vivek Goyal]

On Fri, Sep 12, 2014 at 07:56:10AM -0400, Minfei Huang wrote:

[..]
> 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.

So what does dhclient.conf do?
> 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.

Sorry, I still did not get that why should we ignore PEERDNS if
specified in ifcfg*.

Thanks
Vivek

[Minfei Huang]

On 09/12/2014 08:09 PM, Vivek Goyal wrote:
> On Fri, Sep 12, 2014 at 07:56:10AM -0400, Minfei Huang wrote:
>
> [..]
> > 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.
>
> So what does dhclient.conf do?

We can add following to the /etc/dhclient.conf, the /etc/resolv.conf 
will add the relevant configruation automatically by step.

supersede domain-name "machine.test.group";
supersede domain-name-servers 10.125.97.171, 10.126.98.43, 10.125.97.176;

Then the /etc/resolv.conf will be:

domain machine.test.group
search machine.test.group nay.redhat.com. redhat.com.
nameserver 10.125.97.171
nameserver 10.126.98.43
nameserver 10.125.97.176

The search domain and DNS generate by the dhclient.conf which the custom 
wants.
> > 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.
>
> Sorry, I still did not get that why should we ignore PEERDNS if
> specified in ifcfg*.

if set the PEERDNS=no in ifcfg-*, it implies that custom doesnot want to 
change the resolv.conf by the system.

In the other words, the configuration file /etc/resolv.conf changes 
nothing when setting the PEERDNS=no, although we customize the 
dhclient.conf.

Under the priciple of simple in the second kernel, if customize the 
dhclient.conf, it is default that we should change the search domain and 
DNS by the dhclient.conf, also custom will be glad to see it.

We think that customize the dhclient.conf once, it represents the custom 
want to use the own configuration of search domain and DNS.

So, there is needless to check the PEERDNS in the if ifcfg-*.
> Thanks
> Vivek

[Vivek Goyal]

On Fri, Sep 12, 2014 at 08:55:53AM -0400, Minfei Huang wrote:
> On 09/12/2014 08:09 PM, Vivek Goyal wrote:
> > On Fri, Sep 12, 2014 at 07:56:10AM -0400, Minfei Huang wrote:
> >
> > [..]
> > > 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.
> >
> > So what does dhclient.conf do?
>
> We can add following to the /etc/dhclient.conf, the /etc/resolv.conf 
> will add the relevant configruation automatically by step.
>
> supersede domain-name "machine.test.group";
> supersede domain-name-servers 10.125.97.171, 10.126.98.43, 10.125.97.176;
>
> Then the /etc/resolv.conf will be:
>
> domain machine.test.group
> search machine.test.group nay.redhat.com. redhat.com.
> nameserver 10.125.97.171
> nameserver 10.126.98.43
> nameserver 10.125.97.176
>
> The search domain and DNS generate by the dhclient.conf which the custom 
> wants.
> > > 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.
> >
> > Sorry, I still did not get that why should we ignore PEERDNS if
> > specified in ifcfg*.
>
> if set the PEERDNS=no in ifcfg-*, it implies that custom doesnot want to 
> change the resolv.conf by the system.
>
> In the other words, the configuration file /etc/resolv.conf changes 
> nothing when setting the PEERDNS=no, although we customize the 
> dhclient.conf.
>
> Under the priciple of simple in the second kernel, if customize the 
> dhclient.conf, it is default that we should change the search domain and 
> DNS by the dhclient.conf, also custom will be glad to see it.
>
> We think that customize the dhclient.conf once, it represents the custom 
> want to use the own configuration of search domain and DNS.
>
> So, there is needless to check the PEERDNS in the if ifcfg-*.

Ok, thanks. Few more questions.

- So what dhclient.conf dracut is including in initramfs. Is it same
  dhclient.conf as in /etc/?

- Bug seems to be saying entirely different thing. They seem to be
  suggesting that honor PEERDNS instead of ignoring it.

- As per your description it seems to make no sense to use PEERDNS=no as
  we has specify something in dhclient.conf. If we want dhclient.conf
  to take affect then we should not specify PEERDNS=no. That seems to
  be a configuration issue and not a software bug?

Thanks
Vivek
> > Thanks
> > Vivek
>
> -- 
> Minfei
> _______________________________________________
> kexec mailing list
> [e-mail]
> https://lists.fedoraproject.org/mailman/listinfo/kexec