[PATCH] module-setup: Fix improper dns setup in kdump_setup_dns()

[Xunlei Pang]

Current implementation of kdump_setup_dns() get the dns
from interface's ifcfg file first, then parse those in
"/etc/resolv.conf". For example, DNS1 in ifcfg file along
with dhcp, the final dns(/etc/resolv.conf) in 1st system
will be like(dhcp first, then ifcfg file appending end):
    dhcp dns1
    dhcp dns2
    dhcp dns3
    DNS1 in ifcfg

After parsing, the dns(/etc/cmdline.d/42dns.conf) in kdump
system will be like:
    DNS1 in ifcfg
    dhcp dns1
    dhcp dns2
    dhcp dns3
    DNS1 in ifcfg

There are two issues by doing this:
1) The dns sequence is different from that in 1st system.
2) There are some duplicated items.
   NOTE: kdump_setup_dns() meant to avoid the duplication,
   but the original shell command is actually disfunctional:
   "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)

Fix the issues by firstly parsing "/etc/resolv.conf", then
parsing ifcfg file, finally delete the duplicated items.

Signed-off-by: Xunlei Pang 
---
 dracut-module-setup.sh | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
index 350864e..b7763f7 100755
--- a/dracut-module-setup.sh
+++ b/dracut-module-setup.sh
@@ -68,14 +68,6 @@ kdump_setup_dns() {
     local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
     local ifcfg_file

-    ifcfg_file=$(get_ifcfg_filename $1)
-    if [ -f "${ifcfg_file}" ]; then
-        . ${ifcfg_file}
-    fi
-
-    [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
-    [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
-
     while read content;
     do
         _nameserver=$(echo $content | grep ^nameserver)
@@ -84,10 +76,23 @@ kdump_setup_dns() {
         _dns=$(echo $_nameserver | cut -d' ' -f2)
         [ -z "$_dns" ] && continue

-        if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
-            echo "nameserver=$_dns" >> "$_dnsfile"
-        fi
+        echo "nameserver=$_dns" >> "$_dnsfile"
     done < "/etc/resolv.conf"
+
+    unset DNS1 DNS2
+    ifcfg_file=$(get_ifcfg_filename $1)
+    if [ -f "${ifcfg_file}" ]; then
+        . ${ifcfg_file}
+    fi
+
+    [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
+    [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
+
+    # Delete duplicated lines
+    if [ -f "$_dnsfile" ]; then
+        awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
+        mv -f $_dnsfile.tmp $_dnsfile
+    fi
 }

#$1: netdev name

[Xunlei Pang]

On 2016/04/21 at 15:44, Xunlei Pang wrote:
> Current implementation of kdump_setup_dns() get the dns
> from interface's ifcfg file first, then parse those in
> "/etc/resolv.conf". For example, DNS1 in ifcfg file along
> with dhcp, the final dns(/etc/resolv.conf) in 1st system
> will be like(dhcp first, then ifcfg file appending end):
>     dhcp dns1
>     dhcp dns2
>     dhcp dns3
>     DNS1 in ifcfg
>
> After parsing, the dns(/etc/cmdline.d/42dns.conf) in kdump
> system will be like:
>     DNS1 in ifcfg
>     dhcp dns1
>     dhcp dns2
>     dhcp dns3
>     DNS1 in ifcfg
>
> There are two issues by doing this:
> The dns sequence is different from that in 1st system.
> There are some duplicated items.
> NOTE: kdump_setup_dns() meant to avoid the duplication,
> but the original shell command is actually disfunctional:
> "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)
>
> Fix the issues by firstly parsing "/etc/resolv.conf", then
> parsing ifcfg file, finally delete the duplicated items.
> Signed-off-by: Xunlei Pang
>
> dracut-module-setup.sh | 27 ++++++++++++++++-----------
>  1 file changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> index 350864e..b7763f7 100755
> --- a/dracut-module-setup.sh
> +++ b/dracut-module-setup.sh
> @@ -68,14 +68,6 @@ kdump_setup_dns() {
>      local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
>      local ifcfg_file
> ifcfg_file=$(get_ifcfg_filename $1)
> if [ -f "${ifcfg_file}" ]; then
>    . ${ifcfg_file}
> fi
> [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
> [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> while read content;
>    do
>        _nameserver=$(echo $content | grep ^nameserver)
>
> @@ -84,10 +76,23 @@ kdump_setup_dns() {
>          _dns=$(echo $_nameserver | cut -d' ' -f2)
>          [ -z "$_dns" ] && continue
>    if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
>        echo "nameserver=$_dns" >> "$_dnsfile"
>    fi
>    echo "nameserver=$_dns" >> "$_dnsfile"
> done < "/etc/resolv.conf"
> unset DNS1 DNS2
> ifcfg_file=$(get_ifcfg_filename $1)
> if [ -f "${ifcfg_file}" ]; then
>    . ${ifcfg_file}
> fi
> [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
> [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> # Delete duplicated lines
> if [ -f "$_dnsfile" ]; then
>    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
>    mv -f $_dnsfile.tmp $_dnsfile
> fi

I will send a patch applying "Delete duplicated lines" logic on dracut side as well.

Regards,
Xunlei
> }
>
> #$1: netdev name

[Minfei Huang]

On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> Current implementation of kdump_setup_dns() get the dns
> from interface's ifcfg file first, then parse those in
> "/etc/resolv.conf". For example, DNS1 in ifcfg file along
> with dhcp, the final dns(/etc/resolv.conf) in 1st system
> will be like(dhcp first, then ifcfg file appending end):
>     dhcp dns1
>     dhcp dns2
>     dhcp dns3
>     DNS1 in ifcfg
>
> After parsing, the dns(/etc/cmdline.d/42dns.conf) in kdump
> system will be like:
>     DNS1 in ifcfg
>     dhcp dns1
>     dhcp dns2
>     dhcp dns3
>     DNS1 in ifcfg

Hi.

I have some confusion about the dns order in /etc/resolv.conf. From my
test, I found that dns client would append DNS entry to /etc/resolv.conf
in kdump kernel. Following is my test result.

kdump:/# cat /sysroot/etc/resolv.conf
# Generated by NetworkManager
search nay.redhat.com redhat.com
nameserver 10.72.17.5
nameserver 10.68.5.26
nameserver 192.168.122.1
nameserver 8.8.8.8

kdump:/# cat /etc/resolv.conf
nameserver 10.72.17.5
nameserver 10.68.5.26
nameserver 192.168.122.1
nameserver 8.8.8.8
nameserver 192.168.122.1

The last dns entry "nameserver 192.168.122.1" is appended in kdump
kernel by DNS client. So the order may be like this:
dhcp dns1
DNS1
dhcp dns1

Thanks
Minfei
> There are two issues by doing this:
> The dns sequence is different from that in 1st system.
> There are some duplicated items.
> NOTE: kdump_setup_dns() meant to avoid the duplication,
> but the original shell command is actually disfunctional:
> "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)
>
> Fix the issues by firstly parsing "/etc/resolv.conf", then
> parsing ifcfg file, finally delete the duplicated items.
> Signed-off-by: Xunlei Pang
>
> dracut-module-setup.sh | 27 ++++++++++++++++-----------
>  1 file changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> index 350864e..b7763f7 100755
> --- a/dracut-module-setup.sh
> +++ b/dracut-module-setup.sh
> @@ -68,14 +68,6 @@ kdump_setup_dns() {
>      local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
>      local ifcfg_file
> ifcfg_file=$(get_ifcfg_filename $1)
> if [ -f "${ifcfg_file}" ]; then
>    . ${ifcfg_file}
> fi
> [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
> [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> while read content;
>    do
>        _nameserver=$(echo $content | grep ^nameserver)
>
> @@ -84,10 +76,23 @@ kdump_setup_dns() {
>          _dns=$(echo $_nameserver | cut -d' ' -f2)
>          [ -z "$_dns" ] && continue
>    if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
>        echo "nameserver=$_dns" >> "$_dnsfile"
>    fi
>    echo "nameserver=$_dns" >> "$_dnsfile"
> done < "/etc/resolv.conf"
> unset DNS1 DNS2
> ifcfg_file=$(get_ifcfg_filename $1)
> if [ -f "${ifcfg_file}" ]; then
>    . ${ifcfg_file}
> fi
> [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
> [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> # Delete duplicated lines
> if [ -f "$_dnsfile" ]; then
>    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
>    mv -f $_dnsfile.tmp $_dnsfile
> fi
>
> }
> #$1: netdev name
>
> 1.8.3.1
> _______________________________________________
> kexec mailing list
> [e-mail]
> http://lists.fedoraproject.org/admin/lists/[e-mail]

[Xunlei Pang]

On 2016/04/22 at 16:58, Minfei Huang wrote:
> On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> > Current implementation of kdump_setup_dns() get the dns
> > from interface's ifcfg file first, then parse those in
> > "/etc/resolv.conf". For example, DNS1 in ifcfg file along
> > with dhcp, the final dns(/etc/resolv.conf) in 1st system
> > will be like(dhcp first, then ifcfg file appending end):
> >     dhcp dns1
> >     dhcp dns2
> >     dhcp dns3
> >     DNS1 in ifcfg
> >
> > After parsing, the dns(/etc/cmdline.d/42dns.conf) in kdump
> > system will be like:
> >     DNS1 in ifcfg
> >     dhcp dns1
> >     dhcp dns2
> >     dhcp dns3
> >     DNS1 in ifcfg
>
> Hi.
>
> I have some confusion about the dns order in /etc/resolv.conf. From my
> test, I found that dns client would append DNS entry to /etc/resolv.conf
> in kdump kernel. Following is my test result.
>
> kdump:/# cat /sysroot/etc/resolv.conf
> # Generated by NetworkManager
> search nay.redhat.com redhat.com
> nameserver 10.72.17.5
> nameserver 10.68.5.26
> nameserver 192.168.122.1
> nameserver 8.8.8.8
>
> kdump:/# cat /etc/resolv.conf
> nameserver 10.72.17.5
> nameserver 10.68.5.26
> nameserver 192.168.122.1
> nameserver 8.8.8.8
> nameserver 192.168.122.1
>
> The last dns entry "nameserver 192.168.122.1" is appended in kdump
> kernel by DNS client. So the order may be like this:
> dhcp dns1
> DNS1
> dhcp dns1

Thanks for the test, the Dracut's dhcp order may have problems,
it should be like network-manager: dhcp firstly, then append DNS<n> in ifcfg files.

I will double confirm this later.

Regards,
Xunlei
> Thanks
> Minfei
> > There are two issues by doing this:
> > The dns sequence is different from that in 1st system.
> > There are some duplicated items.
> > NOTE: kdump_setup_dns() meant to avoid the duplication,
> > but the original shell command is actually disfunctional:
> > "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)
> >
> > Fix the issues by firstly parsing "/etc/resolv.conf", then
> > parsing ifcfg file, finally delete the duplicated items.
> > Signed-off-by: Xunlei Pang
> >
> > dracut-module-setup.sh | 27 ++++++++++++++++-----------
> >  1 file changed, 16 insertions(+), 11 deletions(-)
> >
> > diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> > index 350864e..b7763f7 100755
> > --- a/dracut-module-setup.sh
> > +++ b/dracut-module-setup.sh
> > @@ -68,14 +68,6 @@ kdump_setup_dns() {
> >      local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
> >      local ifcfg_file
> > ifcfg_file=$(get_ifcfg_filename $1)
> > if [ -f "${ifcfg_file}" ]; then
> >    . ${ifcfg_file}
> > fi
> > [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
> > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > while read content;
> >    do
> >        _nameserver=$(echo $content | grep ^nameserver)
> >
> > @@ -84,10 +76,23 @@ kdump_setup_dns() {
> >          _dns=$(echo $_nameserver | cut -d' ' -f2)
> >          [ -z "$_dns" ] && continue
> >    if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
> >        echo "nameserver=$_dns" >> "$_dnsfile"
> >    fi
> >    echo "nameserver=$_dns" >> "$_dnsfile"
> > done < "/etc/resolv.conf"
> > unset DNS1 DNS2
> > ifcfg_file=$(get_ifcfg_filename $1)
> > if [ -f "${ifcfg_file}" ]; then
> >    . ${ifcfg_file}
> > fi
> > [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
> > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > # Delete duplicated lines
> > if [ -f "$_dnsfile" ]; then
> >    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
> >    mv -f $_dnsfile.tmp $_dnsfile
> > fi
> >
> > }
> > #$1: netdev name
> >
> > 1.8.3.1
> > _______________________________________________
> > kexec mailing list
> > [e-mail]
> > http://lists.fedoraproject.org/admin/lists/[e-mail]

[Xunlei Pang]

On 2016/04/22 at 22:53, Xunlei Pang wrote:
> On 2016/04/22 at 16:58, Minfei Huang wrote:
> > On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> > > Current implementation of kdump_setup_dns() get the dns
> > > from interface's ifcfg file first, then parse those in
> > > "/etc/resolv.conf". For example, DNS1 in ifcfg file along
> > > with dhcp, the final dns(/etc/resolv.conf) in 1st system
> > > will be like(dhcp first, then ifcfg file appending end):
> > >     dhcp dns1
> > >     dhcp dns2
> > >     dhcp dns3
> > >     DNS1 in ifcfg
> > >
> > > After parsing, the dns(/etc/cmdline.d/42dns.conf) in kdump
> > > system will be like:
> > >     DNS1 in ifcfg
> > >     dhcp dns1
> > >     dhcp dns2
> > >     dhcp dns3
> > >     DNS1 in ifcfg
> >
> > Hi.
> >
> > I have some confusion about the dns order in /etc/resolv.conf. From my
> > test, I found that dns client would append DNS entry to /etc/resolv.conf
> > in kdump kernel. Following is my test result.
> >
> > kdump:/# cat /sysroot/etc/resolv.conf
> > # Generated by NetworkManager
> > search nay.redhat.com redhat.com
> > nameserver 10.72.17.5
> > nameserver 10.68.5.26
> > nameserver 192.168.122.1
> > nameserver 8.8.8.8
> >
> > kdump:/# cat /etc/resolv.conf
> > nameserver 10.72.17.5
> > nameserver 10.68.5.26
> > nameserver 192.168.122.1
> > nameserver 8.8.8.8
> > nameserver 192.168.122.1
> >
> > The last dns entry "nameserver 192.168.122.1" is appended in kdump
> > kernel by DNS client. So the order may be like this:
> > dhcp dns1
> > DNS1
> > dhcp dns1
>
> Thanks for the test, the Dracut's dhcp order may have problems,
> it should be like network-manager: dhcp firstly, then append DNS<n> in ifcfg files.
>
> I will double confirm this later.

I checked the implementation of /etc/sysconfig/network-scripts/ and the actual effect
of network-manager, they are differently implemented. Seems there is no standard to
follow. I'd rather leave this alone(only improve the duplicated items) for safety as we
discussed last week, since there are no bugs related to this reported.

Regards,
Xunlei
> Regards,
> Xunlei
> > Thanks
> > Minfei
> > > There are two issues by doing this:
> > > The dns sequence is different from that in 1st system.
> > > There are some duplicated items.
> > > NOTE: kdump_setup_dns() meant to avoid the duplication,
> > > but the original shell command is actually disfunctional:
> > > "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)
> > >
> > > Fix the issues by firstly parsing "/etc/resolv.conf", then
> > > parsing ifcfg file, finally delete the duplicated items.
> > > Signed-off-by: Xunlei Pang
> > >
> > > dracut-module-setup.sh | 27 ++++++++++++++++-----------
> > >  1 file changed, 16 insertions(+), 11 deletions(-)
> > >
> > > diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> > > index 350864e..b7763f7 100755
> > > --- a/dracut-module-setup.sh
> > > +++ b/dracut-module-setup.sh
> > > @@ -68,14 +68,6 @@ kdump_setup_dns() {
> > >      local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
> > >      local ifcfg_file
> > > ifcfg_file=$(get_ifcfg_filename $1)
> > > if [ -f "${ifcfg_file}" ]; then
> > >    . ${ifcfg_file}
> > > fi
> > > [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
> > > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > > while read content;
> > >    do
> > >        _nameserver=$(echo $content | grep ^nameserver)
> > >
> > > @@ -84,10 +76,23 @@ kdump_setup_dns() {
> > >          _dns=$(echo $_nameserver | cut -d' ' -f2)
> > >          [ -z "$_dns" ] && continue
> > >    if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
> > >        echo "nameserver=$_dns" >> "$_dnsfile"
> > >    fi
> > >    echo "nameserver=$_dns" >> "$_dnsfile"
> > > done < "/etc/resolv.conf"
> > > unset DNS1 DNS2
> > > ifcfg_file=$(get_ifcfg_filename $1)
> > > if [ -f "${ifcfg_file}" ]; then
> > >    . ${ifcfg_file}
> > > fi
> > > [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
> > > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > > # Delete duplicated lines
> > > if [ -f "$_dnsfile" ]; then
> > >    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
> > >    mv -f $_dnsfile.tmp $_dnsfile
> > > fi
> > >
> > > }
> > > #$1: netdev name
> > >
> > > 1.8.3.1
> > > _______________________________________________
> > > kexec mailing list
> > > [e-mail]
> > > http://lists.fedoraproject.org/admin/lists/[e-mail]
>
> kexec mailing list
> [e-mail]
> http://lists.fedoraproject.org/admin/lists/[e-mail]

[Baoquan He]

On 04/25/16 at 10:56am, Xunlei Pang wrote:
> On 2016/04/22 at 22:53, Xunlei Pang wrote:
> > On 2016/04/22 at 16:58, Minfei Huang wrote:
> > > On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> > > > Current implementation of kdump_setup_dns() get the dns
> > > > from interface's ifcfg file first, then parse those in
> > > > "/etc/resolv.conf". For example, DNS1 in ifcfg file along
> > > > with dhcp, the final dns(/etc/resolv.conf) in 1st system
> > > > will be like(dhcp first, then ifcfg file appending end):
> > > >     dhcp dns1
> > > >     dhcp dns2
> > > >     dhcp dns3
> > > >     DNS1 in ifcfg
> > > >
> > > > After parsing, the dns(/etc/cmdline.d/42dns.conf) in kdump
> > > > system will be like:
> > > >     DNS1 in ifcfg
> > > >     dhcp dns1
> > > >     dhcp dns2
> > > >     dhcp dns3
> > > >     DNS1 in ifcfg
> > >
> > > Hi.
> > >
> > > I have some confusion about the dns order in /etc/resolv.conf. From my
> > > test, I found that dns client would append DNS entry to /etc/resolv.conf
> > > in kdump kernel. Following is my test result.
> > >
> > > kdump:/# cat /sysroot/etc/resolv.conf
> > > # Generated by NetworkManager
> > > search nay.redhat.com redhat.com
> > > nameserver 10.72.17.5
> > > nameserver 10.68.5.26
> > > nameserver 192.168.122.1
> > > nameserver 8.8.8.8
> > >
> > > kdump:/# cat /etc/resolv.conf
> > > nameserver 10.72.17.5
> > > nameserver 10.68.5.26
> > > nameserver 192.168.122.1
> > > nameserver 8.8.8.8
> > > nameserver 192.168.122.1
> > >
> > > The last dns entry "nameserver 192.168.122.1" is appended in kdump
> > > kernel by DNS client. So the order may be like this:
> > > dhcp dns1
> > > DNS1
> > > dhcp dns1
> >
> > Thanks for the test, the Dracut's dhcp order may have problems,
> > it should be like network-manager: dhcp firstly, then append DNS<n> in ifcfg files.
> >
> > I will double confirm this later.
>
> I checked the implementation of /etc/sysconfig/network-scripts/ and the actual effect
> of network-manager, they are differently implemented. Seems there is no standard to
> follow. I'd rather leave this alone(only improve the duplicated items) for safety as we
> discussed last week, since there are no bugs related to this reported.

I think we can summarize the knowing we have discussed about
the behaviour of Netowrkmanager, network-scripts and dracut
implementation on dns. Then ask network expert to help to check this,
which one is reasonable. After making this clear proper fix can be done.
> Regards,
> Xunlei
> > Regards,
> > Xunlei
> > > Thanks
> > > Minfei
> > > > There are two issues by doing this:
> > > > The dns sequence is different from that in 1st system.
> > > > There are some duplicated items.
> > > > NOTE: kdump_setup_dns() meant to avoid the duplication,
> > > > but the original shell command is actually disfunctional:
> > > > "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)
> > > >
> > > > Fix the issues by firstly parsing "/etc/resolv.conf", then
> > > > parsing ifcfg file, finally delete the duplicated items.
> > > > Signed-off-by: Xunlei Pang
> > > >
> > > > dracut-module-setup.sh | 27 ++++++++++++++++-----------
> > > >  1 file changed, 16 insertions(+), 11 deletions(-)
> > > >
> > > > diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> > > > index 350864e..b7763f7 100755
> > > > --- a/dracut-module-setup.sh
> > > > +++ b/dracut-module-setup.sh
> > > > @@ -68,14 +68,6 @@ kdump_setup_dns() {
> > > >      local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
> > > >      local ifcfg_file
> > > > ifcfg_file=$(get_ifcfg_filename $1)
> > > > if [ -f "${ifcfg_file}" ]; then
> > > >    . ${ifcfg_file}
> > > > fi
> > > > [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
> > > > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > > > while read content;
> > > >    do
> > > >        _nameserver=$(echo $content | grep ^nameserver)
> > > >
> > > > @@ -84,10 +76,23 @@ kdump_setup_dns() {
> > > >          _dns=$(echo $_nameserver | cut -d' ' -f2)
> > > >          [ -z "$_dns" ] && continue
> > > >    if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
> > > >        echo "nameserver=$_dns" >> "$_dnsfile"
> > > >    fi
> > > >    echo "nameserver=$_dns" >> "$_dnsfile"
> > > > done < "/etc/resolv.conf"
> > > > unset DNS1 DNS2
> > > > ifcfg_file=$(get_ifcfg_filename $1)
> > > > if [ -f "${ifcfg_file}" ]; then
> > > >    . ${ifcfg_file}
> > > > fi
> > > > [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
> > > > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > > > # Delete duplicated lines
> > > > if [ -f "$_dnsfile" ]; then
> > > >    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
> > > >    mv -f $_dnsfile.tmp $_dnsfile
> > > > fi
> > > >
> > > > }
> > > > #$1: netdev name
> > > >
> > > > 1.8.3.1
> > > > _______________________________________________
> > > > kexec mailing list
> > > > [e-mail]
> > > > http://lists.fedoraproject.org/admin/lists/[e-mail]
> >
> > kexec mailing list
> > [e-mail]
> > http://lists.fedoraproject.org/admin/lists/[e-mail]
>
> kexec mailing list
> [e-mail]
> http://lists.fedoraproject.org/admin/lists/[e-mail]

[Xunlei Pang]

On 2016/04/25 at 13:24, Baoquan He wrote:
> On 04/25/16 at 10:56am, Xunlei Pang wrote:
> > On 2016/04/22 at 22:53, Xunlei Pang wrote:
> > > On 2016/04/22 at 16:58, Minfei Huang wrote:
> > > > On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> > > > > Current implementation of kdump_setup_dns() get the dns
> > > > > from interface's ifcfg file first, then parse those in
> > > > > "/etc/resolv.conf". For example, DNS1 in ifcfg file along
> > > > > with dhcp, the final dns(/etc/resolv.conf) in 1st system
> > > > > will be like(dhcp first, then ifcfg file appending end):
> > > > >     dhcp dns1
> > > > >     dhcp dns2
> > > > >     dhcp dns3
> > > > >     DNS1 in ifcfg
> > > > >
> > > > > After parsing, the dns(/etc/cmdline.d/42dns.conf) in kdump
> > > > > system will be like:
> > > > >     DNS1 in ifcfg
> > > > >     dhcp dns1
> > > > >     dhcp dns2
> > > > >     dhcp dns3
> > > > >     DNS1 in ifcfg
> > > >
> > > > Hi.
> > > >
> > > > I have some confusion about the dns order in /etc/resolv.conf. From my
> > > > test, I found that dns client would append DNS entry to /etc/resolv.conf
> > > > in kdump kernel. Following is my test result.
> > > >
> > > > kdump:/# cat /sysroot/etc/resolv.conf
> > > > # Generated by NetworkManager
> > > > search nay.redhat.com redhat.com
> > > > nameserver 10.72.17.5
> > > > nameserver 10.68.5.26
> > > > nameserver 192.168.122.1
> > > > nameserver 8.8.8.8
> > > >
> > > > kdump:/# cat /etc/resolv.conf
> > > > nameserver 10.72.17.5
> > > > nameserver 10.68.5.26
> > > > nameserver 192.168.122.1
> > > > nameserver 8.8.8.8
> > > > nameserver 192.168.122.1
> > > >
> > > > The last dns entry "nameserver 192.168.122.1" is appended in kdump
> > > > kernel by DNS client. So the order may be like this:
> > > > dhcp dns1
> > > > DNS1
> > > > dhcp dns1
> > >
> > > Thanks for the test, the Dracut's dhcp order may have problems,
> > > it should be like network-manager: dhcp firstly, then append DNS<n> in ifcfg files.
> > >
> > > I will double confirm this later.
> >
> > I checked the implementation of /etc/sysconfig/network-scripts/ and the actual effect
> > of network-manager, they are differently implemented. Seems there is no standard to
> > follow. I'd rather leave this alone(only improve the duplicated items) for safety as we
> > discussed last week, since there are no bugs related to this reported.
>
> I think we can summarize the knowing we have discussed about
> the behaviour of Netowrkmanager, network-scripts and dracut
> implementation on dns. Then ask network expert to help to check this,
> which one is reasonable. After making this clear proper fix can be done.

Hereby I only summarize dhcp cases for specific $netif about the main process of dns handling, static cases is similar.

============= 1. The DNS handling in 1st kernel after the dracut stage =============

There are two network methods available in 1st kernel:
network-manager(nmcli) and
network-scripts(without network-manager by using scripts under /etc/sysconfig/network-scripts/,
such as "if-eth", "ifup-post", etc).

a) The general entry is "/usr/sbin/ifup":
    need_config // find the right ifcfg file of the $config
    source_config // load the ifcfg file contents

b) Then if it is network-manager controlled, bring it up firstly via nmcli:  
    if [ "$_use_nm" = "true" -a -n "$UUID" -a "$DEVICE" != "lo" ]; then
        if [ "foo$2" = "fooboot" ] && [ "${TYPE}" = "Wireless" ]; then
            exit 0
        fi 
        [ -n "${DEVICE}" ] && is_nm_handling ${DEVICE} && exit 0
        nmcli con up uuid "$UUID"
        exit $?
    fi

All things are done by nmcli which is an ELF file, I didn't get its detail.
    All the knowledge if through experiments:
    -) Generate dhcp firstly
    -) Append the DNS1&DNS2 info in ifcfg to /etc/resolv.conf
    -) From my experiment, seems "PEERDNS=yes" and "PEERDNS=no" have the same effect.

c) Otherwise(without network-manager), it will generally use scripts under
   "/etc/sysconfig/network-scripts/" to do the job:
    OTHERSCRIPT="/etc/sysconfig/network-scripts/ifup-${DEVICETYPE}"

if [ ! -x ${OTHERSCRIPT} ]; then
        OTHERSCRIPT="/etc/sysconfig/network-scripts/ifup-${TYPE}"
    fi

if [ ! -x ${OTHERSCRIPT} ]; then
        OTHERSCRIPT="/etc/sysconfig/network-scripts/ifup-eth"
    fi

exec ${OTHERSCRIPT} ${CONFIG} $2

d) Suppose we have ethernet type, ${OTHERSCRIPTS} is "ifup-eth", we enter "ifup-eth":
  After some specific type-parsing(bridge, vlan, team, etc), it will generally call
  "dhclient" to do the dhcp firstly.
  "/usr/sbin/dhclient-script" is called by "dhclient" to generate the initial "/etc/resolv.conf" file,
  can refer to function "make_resolv_conf" in dhclient-script for details.
      make_resolv_conf() {
          [ "${PEERDNS}" = "no" ] && return // handle PEERDNS

generate dns information to file ${rscf} using the contents provided by "dhclient"

change_resolv_conf ${rscf}

e) Finally, "ifup-post" script is called, it does mainly(omit some detail here):
 if [ "$PEERDNS" != "no" ] ; then  // handle PEERDNS
  if [ -n "$DNS1" ] && ! grep -q "^nameserver $DNS1" /etc/resolv.conf &&
   tr=$(mktemp /tmp/XXXXXX) ; then
    current_replacement="$DNS1"
    next_replacement="$DNS2"
    search=
    (cat /etc/resolv.conf ; echo EOF ; echo EOF) | while read answer ; do
    case $answer in
        nameserver*|EOF)
        if [ -n "$current_replacement" ] ; then
            echo "nameserver $current_replacement" >> $tr
            if [ -n "$next_replacement" ] ; then
            current_replacement="$next_replacement"
            next_replacement=
            else
            current_replacement=
            fi 
        else
            if [ "$answer" != EOF ] ; then
            echo "$answer" >> $tr
            fi 
        fi 
        ;; 
        <snip>
    esac
    done
    change_resolv_conf $tr
  fi
fi

============= 2. The DNS handling in dump kernel by dracut =============
Using scripts under modules.d/40network/
a) The general entry is "ifup":

b) do nameserver and dns1/dns2 firstly, which is acquired from "nameserver=" and "ip="
   cmdline of dracut setup in 1st kernel when making kdump initramfs.
   # Specific configuration, spin through the kernel command line
   # looking for ip= lines
   for p in $(getargs ip=); do
        ip_to_var $p

<snip>

# setup nameserver
        for s in "$dns1" "$dns2" $(getargs nameserver); do
            [ -n "$s" ] || continue
            echo nameserver $s >> /tmp/net.$netif.resolv.conf  // Apparently, not deal with rd.peerdns
        done

c) "do_dhcp -4 ;;"
This will trigger dhclient and "modules.d/40network/dhclient-script.sh",
in setup_interface(), dracut will append dhcp-generated DNS information
into "/tmp/net.$netif.resolv.conf":
    if getargbool 1 rd.peerdns; then // handle rd.peerdns globally
        [ -n "${search}${domain}" ] && echo "search $search $domain" > /tmp/net.$netif.resolv.conf
        if  [ -n "$namesrv" ] ; then
            for s in $namesrv; do
                echo nameserver $s
            done
        fi >> /tmp/net.$netif.resolv.conf  // append dhcp dns
    fi

d) execute setup_net through initqueue scripts
     [ -e /tmp/net.$netif.resolv.conf ] && \
         cp -f /tmp/net.$netif.resolv.conf /etc/resolv.conf

============= 3. Conclusion =============
Dracut, network-manager, and "network-scripts" all have different hehavior
in handling DNS.

As a dhcp example:
Suppose enp0s25, the dhcped DNSes are stable: 10.72.17.5 and 10.68.5.26

In ifcfg-enp0s25:
DNS1: 8.8.8.8

1) For 1st kernel's network-manager, the final nameservers in /etc/resolv.conf
   -) If PEERDNS=yes(default is yes if PEERDNS doesn't exist) in ifcfg-enp0s25
       nameserver 10.72.17.5
       nameserver 10.68.5.26
       nameserver 8.8.8.8
   -) If PEERDNS=no in ifcfg-enp0s25
       nameserver 10.72.17.5
       nameserver 10.68.5.26
       nameserver 8.8.8.8

2) For 1st kernel's scripts under /etc/sysconfig/network-scripts/ without network-manager
   -) If PEERDNS=yes in ifcfg-enp0s25
       nameserver 8.8.8.8
       nameserver 10.68.5.26
   -) If PEERDNS=no in ifcfg-enp0s25
       Not touch /etc/resolv.conf
       (i.e. /etc/resolv.conf is left unchanged as that before calling "ifup <config>")

3) For dracut in latest fedora kexec-tools(1st kernel using network-manager)
   "${initdir}/etc/cmdline.d/42dns.conf" will contain:
       nameserver=8.8.8.8
       nameserver=10.72.17.5
       nameserver=10.68.5.26
       nameserver=8.8.8.8

-) If "rd.peerdns=1"(default is "1" if "rd.peerdns" doesn't exist) is passed which is the default case
       nameserver 8.8.8.8
       nameserver 10.72.17.5
       nameserver 10.68.5.26
       nameserver 8.8.8.8
       nameserver 10.72.17.5 // the last two are drauct' dhcp generated items
       nameserver 10.68.5.26
   -) If "rd.peerdns=0" is passed
       nameserver 8.8.8.8
       nameserver 10.72.17.5
       nameserver 10.68.5.26
       nameserver 8.8.8.8

Regards,
Xunlei
> > Regards,
> > Xunlei
> > > Regards,
> > > Xunlei
> > > > Thanks
> > > > Minfei
> > > > > There are two issues by doing this:
> > > > > The dns sequence is different from that in 1st system.
> > > > > There are some duplicated items.
> > > > > NOTE: kdump_setup_dns() meant to avoid the duplication,
> > > > > but the original shell command is actually disfunctional:
> > > > > "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)
> > > > >
> > > > > Fix the issues by firstly parsing "/etc/resolv.conf", then
> > > > > parsing ifcfg file, finally delete the duplicated items.
> > > > > Signed-off-by: Xunlei Pang
> > > > >
> > > > > dracut-module-setup.sh | 27 ++++++++++++++++-----------
> > > > >  1 file changed, 16 insertions(+), 11 deletions(-)
> > > > >
> > > > > diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> > > > > index 350864e..b7763f7 100755
> > > > > --- a/dracut-module-setup.sh
> > > > > +++ b/dracut-module-setup.sh
> > > > > @@ -68,14 +68,6 @@ kdump_setup_dns() {
> > > > >      local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
> > > > >      local ifcfg_file
> > > > > ifcfg_file=$(get_ifcfg_filename $1)
> > > > > if [ -f "${ifcfg_file}" ]; then
> > > > >    . ${ifcfg_file}
> > > > > fi
> > > > > [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
> > > > > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > > > > while read content;
> > > > >    do
> > > > >        _nameserver=$(echo $content | grep ^nameserver)
> > > > >
> > > > > @@ -84,10 +76,23 @@ kdump_setup_dns() {
> > > > >          _dns=$(echo $_nameserver | cut -d' ' -f2)
> > > > >          [ -z "$_dns" ] && continue
> > > > >    if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
> > > > >        echo "nameserver=$_dns" >> "$_dnsfile"
> > > > >    fi
> > > > >    echo "nameserver=$_dns" >> "$_dnsfile"
> > > > > done < "/etc/resolv.conf"
> > > > > unset DNS1 DNS2
> > > > > ifcfg_file=$(get_ifcfg_filename $1)
> > > > > if [ -f "${ifcfg_file}" ]; then
> > > > >    . ${ifcfg_file}
> > > > > fi
> > > > > [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
> > > > > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > > > > # Delete duplicated lines
> > > > > if [ -f "$_dnsfile" ]; then
> > > > >    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
> > > > >    mv -f $_dnsfile.tmp $_dnsfile
> > > > > fi
> > > > >
> > > > > }
> > > > > #$1: netdev name
> > > > >
> > > > > 1.8.3.1
> > > > > _______________________________________________
> > > > > kexec mailing list
> > > > > [e-mail]
> > > > > http://lists.fedoraproject.org/admin/lists/[e-mail]
> > >
> > > kexec mailing list
> > > [e-mail]
> > > http://lists.fedoraproject.org/admin/lists/[e-mail]
> >
> > kexec mailing list
> > [e-mail]
> > http://lists.fedoraproject.org/admin/lists/[e-mail]

[Xunlei Pang]

On 2016/04/25 at 15:29, Xunlei Pang wrote:
> On 2016/04/25 at 13:24, Baoquan He wrote:
> > On 04/25/16 at 10:56am, Xunlei Pang wrote:
> > > On 2016/04/22 at 22:53, Xunlei Pang wrote:
> > > > On 2016/04/22 at 16:58, Minfei Huang wrote:
> > > > > On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> > > > > > Current implementation of kdump_setup_dns() get the dns
> > > > > > from interface's ifcfg file first, then parse those in
> > > > > > "/etc/resolv.conf". For example, DNS1 in ifcfg file along
> > > > > > with dhcp, the final dns(/etc/resolv.conf) in 1st system
> > > > > > will be like(dhcp first, then ifcfg file appending end):
> > > > > >     dhcp dns1
> > > > > >     dhcp dns2
> > > > > >     dhcp dns3
> > > > > >     DNS1 in ifcfg
> > > > > >
> > > > > > After parsing, the dns(/etc/cmdline.d/42dns.conf) in kdump
> > > > > > system will be like:
> > > > > >     DNS1 in ifcfg
> > > > > >     dhcp dns1
> > > > > >     dhcp dns2
> > > > > >     dhcp dns3
> > > > > >     DNS1 in ifcfg
> > > > >
> > > > > Hi.
> > > > >
> > > > > I have some confusion about the dns order in /etc/resolv.conf. From my
> > > > > test, I found that dns client would append DNS entry to /etc/resolv.conf
> > > > > in kdump kernel. Following is my test result.
> > > > >
> > > > > kdump:/# cat /sysroot/etc/resolv.conf
> > > > > # Generated by NetworkManager
> > > > > search nay.redhat.com redhat.com
> > > > > nameserver 10.72.17.5
> > > > > nameserver 10.68.5.26
> > > > > nameserver 192.168.122.1
> > > > > nameserver 8.8.8.8
> > > > >
> > > > > kdump:/# cat /etc/resolv.conf
> > > > > nameserver 10.72.17.5
> > > > > nameserver 10.68.5.26
> > > > > nameserver 192.168.122.1
> > > > > nameserver 8.8.8.8
> > > > > nameserver 192.168.122.1
> > > > >
> > > > > The last dns entry "nameserver 192.168.122.1" is appended in kdump
> > > > > kernel by DNS client. So the order may be like this:
> > > > > dhcp dns1
> > > > > DNS1
> > > > > dhcp dns1
> > > >
> > > > Thanks for the test, the Dracut's dhcp order may have problems,
> > > > it should be like network-manager: dhcp firstly, then append DNS<n> in ifcfg files.
> > > >
> > > > I will double confirm this later.
> > >
> > > I checked the implementation of /etc/sysconfig/network-scripts/ and the actual effect
> > > of network-manager, they are differently implemented. Seems there is no standard to
> > > follow. I'd rather leave this alone(only improve the duplicated items) for safety as we
> > > discussed last week, since there are no bugs related to this reported.
> >
> > I think we can summarize the knowing we have discussed about
> > the behaviour of Netowrkmanager, network-scripts and dracut
> > implementation on dns. Then ask network expert to help to check this,
> > which one is reasonable. After making this clear proper fix can be done.
>
> Hereby I only summarize dhcp cases for specific $netif about the main process of dns handling, static cases is similar.
>
> ============= 1. The DNS handling in 1st kernel after the dracut stage =============
>
> There are two network methods available in 1st kernel:
> network-manager(nmcli) and
> network-scripts(without network-manager by using scripts under /etc/sysconfig/network-scripts/,
> such as "if-eth", "ifup-post", etc).
>
> a) The general entry is "/usr/sbin/ifup":
>     need_config // find the right ifcfg file of the $config
>     source_config // load the ifcfg file contents
>
> b) Then if it is network-manager controlled, bring it up firstly via nmcli:  
>     if [ "$_use_nm" = "true" -a -n "$UUID" -a "$DEVICE" != "lo" ]; then
>         if [ "foo$2" = "fooboot" ] && [ "${TYPE}" = "Wireless" ]; then
>             exit 0
>         fi 
>         [ -n "${DEVICE}" ] && is_nm_handling ${DEVICE} && exit 0
>         nmcli con up uuid "$UUID"
>         exit $?
>     fi
> All things are done by nmcli which is an ELF file, I didn't get its detail.
> All the knowledge if through experiments:
> -) Generate dhcp firstly
> -) Append the DNS1&DNS2 info in ifcfg to /etc/resolv.conf
> -) From my experiment, seems "PEERDNS=yes" and "PEERDNS=no" have the same effect.
>
> c) Otherwise(without network-manager), it will generally use scripts under
>    "/etc/sysconfig/network-scripts/" to do the job:
>     OTHERSCRIPT="/etc/sysconfig/network-scripts/ifup-${DEVICETYPE}"
> if [ ! -x ${OTHERSCRIPT} ]; then
>     OTHERSCRIPT="/etc/sysconfig/network-scripts/ifup-${TYPE}"
> fi
>
> if [ ! -x ${OTHERSCRIPT} ]; then
>     OTHERSCRIPT="/etc/sysconfig/network-scripts/ifup-eth"
> fi
>
> exec ${OTHERSCRIPT} ${CONFIG} $2
>
> d) Suppose we have ethernet type, ${OTHERSCRIPTS} is "ifup-eth", we enter "ifup-eth":
>   After some specific type-parsing(bridge, vlan, team, etc), it will generally call
>   "dhclient" to do the dhcp firstly.
>   "/usr/sbin/dhclient-script" is called by "dhclient" to generate the initial "/etc/resolv.conf" file,
>   can refer to function "make_resolv_conf" in dhclient-script for details.
>       make_resolv_conf() {
>           [ "${PEERDNS}" = "no" ] && return // handle PEERDNS
>   generate dns information to file ${rscf} using the contents provided by "dhclient"
>
>   change_resolv_conf ${rscf}
>
> e) Finally, "ifup-post" script is called, it does mainly(omit some detail here):
>  if [ "$PEERDNS" != "no" ] ; then  // handle PEERDNS
>   if [ -n "$DNS1" ] && ! grep -q "^nameserver $DNS1" /etc/resolv.conf &&
>    tr=$(mktemp /tmp/XXXXXX) ; then
>     current_replacement="$DNS1"
>     next_replacement="$DNS2"
>     search=
>     (cat /etc/resolv.conf ; echo EOF ; echo EOF) | while read answer ; do
>     case $answer in
>         nameserver*|EOF)
>         if [ -n "$current_replacement" ] ; then
>             echo "nameserver $current_replacement" >> $tr
>             if [ -n "$next_replacement" ] ; then
>             current_replacement="$next_replacement"
>             next_replacement=
>             else
>             current_replacement=
>             fi 
>         else
>             if [ "$answer" != EOF ] ; then
>             echo "$answer" >> $tr
>             fi 
>         fi 
>         ;; 
>         <snip>
>     esac
>     done
>     change_resolv_conf $tr
>   fi
> fi
>
> ============= 2. The DNS handling in dump kernel by dracut =============
> Using scripts under modules.d/40network/
> a) The general entry is "ifup":
>
> b) do nameserver and dns1/dns2 firstly, which is acquired from "nameserver=" and "ip="
>    cmdline of dracut setup in 1st kernel when making kdump initramfs.
>    # Specific configuration, spin through the kernel command line
>    # looking for ip= lines
>    for p in $(getargs ip=); do
>         ip_to_var $p
>     <snip>
>
>     # setup nameserver
>     for s in "$dns1" "$dns2" $(getargs nameserver); do
>         [ -n "$s" ] || continue
>         echo nameserver $s >> /tmp/net.$netif.resolv.conf  // Apparently, not deal with rd.peerdns
>     done
>
> c) "do_dhcp -4 ;;"
> This will trigger dhclient and "modules.d/40network/dhclient-script.sh",
> in setup_interface(), dracut will append dhcp-generated DNS information
> into "/tmp/net.$netif.resolv.conf":
>     if getargbool 1 rd.peerdns; then // handle rd.peerdns globally
>         [ -n "${search}${domain}" ] && echo "search $search $domain" > /tmp/net.$netif.resolv.conf
>         if  [ -n "$namesrv" ] ; then
>             for s in $namesrv; do
>                 echo nameserver $s
>             done
>         fi >> /tmp/net.$netif.resolv.conf  // append dhcp dns
>     fi
>
> d) execute setup_net through initqueue scripts
>      [ -e /tmp/net.$netif.resolv.conf ] && \
>          cp -f /tmp/net.$netif.resolv.conf /etc/resolv.conf
>
> ============= 3. Conclusion =============
> Dracut, network-manager, and "network-scripts" all have different hehavior
> in handling DNS.
>
> As a dhcp example:
> Suppose enp0s25, the dhcped DNSes are stable: 10.72.17.5 and 10.68.5.26
>
> In ifcfg-enp0s25:
> DNS1: 8.8.8.8
> For 1st kernel's network-manager, the final nameservers in /etc/resolv.conf
> -) If PEERDNS=yes(default is yes if PEERDNS doesn't exist) in ifcfg-enp0s25
>     nameserver 10.72.17.5
>     nameserver 10.68.5.26
>     nameserver 8.8.8.8
> -) If PEERDNS=no in ifcfg-enp0s25
>     nameserver 10.72.17.5
>     nameserver 10.68.5.26
>     nameserver 8.8.8.8

network-manager may cache some ifcfg data, I tested further with a complete reboot each time
I changed the ifcfg file:

1) For 1st kernel's network-manager, the final nameservers in /etc/resolv.conf

-) If PEERDNS=yes(default is yes if PEERDNS doesn't exist) in ifcfg-enp0s25
       nameserver 10.72.17.5
       nameserver 10.68.5.26
       nameserver 8.8.8.8
   -) If PEERDNS=no in ifcfg-enp0s25
       nameserver 8.8.8.8

Regards,
Xunlei
> For 1st kernel's scripts under /etc/sysconfig/network-scripts/ without network-manager
> -) If PEERDNS=yes in ifcfg-enp0s25
>     nameserver 8.8.8.8
>     nameserver 10.68.5.26
> -) If PEERDNS=no in ifcfg-enp0s25
>     Not touch /etc/resolv.conf
>     (i.e. /etc/resolv.conf is left unchanged as that before calling "ifup <config>")
>
> For dracut in latest fedora kexec-tools(1st kernel using network-manager)
> "${initdir}/etc/cmdline.d/42dns.conf" will contain:
>     nameserver=8.8.8.8
>     nameserver=10.72.17.5
>     nameserver=10.68.5.26
>     nameserver=8.8.8.8
>
> -) If "rd.peerdns=1"(default is "1" if "rd.peerdns" doesn't exist) is passed which is the default case
>     nameserver 8.8.8.8
>     nameserver 10.72.17.5
>     nameserver 10.68.5.26
>     nameserver 8.8.8.8
>     nameserver 10.72.17.5 // the last two are drauct' dhcp generated items
>     nameserver 10.68.5.26
> -) If "rd.peerdns=0" is passed
>     nameserver 8.8.8.8
>     nameserver 10.72.17.5
>     nameserver 10.68.5.26
>     nameserver 8.8.8.8
>
> Regards,
> Xunlei
> > > Regards,
> > > Xunlei
> > > > Regards,
> > > > Xunlei
> > > > > Thanks
> > > > > Minfei
> > > > > > There are two issues by doing this:
> > > > > > The dns sequence is different from that in 1st system.
> > > > > > There are some duplicated items.
> > > > > > NOTE: kdump_setup_dns() meant to avoid the duplication,
> > > > > > but the original shell command is actually disfunctional:
> > > > > > "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)
> > > > > >
> > > > > > Fix the issues by firstly parsing "/etc/resolv.conf", then
> > > > > > parsing ifcfg file, finally delete the duplicated items.
> > > > > > Signed-off-by: Xunlei Pang
> > > > > >
> > > > > > dracut-module-setup.sh | 27 ++++++++++++++++-----------
> > > > > >  1 file changed, 16 insertions(+), 11 deletions(-)
> > > > > >
> > > > > > diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> > > > > > index 350864e..b7763f7 100755
> > > > > > --- a/dracut-module-setup.sh
> > > > > > +++ b/dracut-module-setup.sh
> > > > > > @@ -68,14 +68,6 @@ kdump_setup_dns() {
> > > > > >      local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
> > > > > >      local ifcfg_file
> > > > > > ifcfg_file=$(get_ifcfg_filename $1)
> > > > > > if [ -f "${ifcfg_file}" ]; then
> > > > > >    . ${ifcfg_file}
> > > > > > fi
> > > > > > [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
> > > > > > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > > > > > while read content;
> > > > > >    do
> > > > > >        _nameserver=$(echo $content | grep ^nameserver)
> > > > > >
> > > > > > @@ -84,10 +76,23 @@ kdump_setup_dns() {
> > > > > >          _dns=$(echo $_nameserver | cut -d' ' -f2)
> > > > > >          [ -z "$_dns" ] && continue
> > > > > >    if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
> > > > > >        echo "nameserver=$_dns" >> "$_dnsfile"
> > > > > >    fi
> > > > > >    echo "nameserver=$_dns" >> "$_dnsfile"
> > > > > > done < "/etc/resolv.conf"
> > > > > > unset DNS1 DNS2
> > > > > > ifcfg_file=$(get_ifcfg_filename $1)
> > > > > > if [ -f "${ifcfg_file}" ]; then
> > > > > >    . ${ifcfg_file}
> > > > > > fi
> > > > > > [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
> > > > > > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > > > > > # Delete duplicated lines
> > > > > > if [ -f "$_dnsfile" ]; then
> > > > > >    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
> > > > > >    mv -f $_dnsfile.tmp $_dnsfile
> > > > > > fi
> > > > > >
> > > > > > }
> > > > > > #$1: netdev name
> > > > > >
> > > > > > 1.8.3.1
> > > > > > _______________________________________________
> > > > > > kexec mailing list
> > > > > > [e-mail]
> > > > > > http://lists.fedoraproject.org/admin/lists/[e-mail]
> > > >
> > > > kexec mailing list
> > > > [e-mail]
> > > > http://lists.fedoraproject.org/admin/lists/[e-mail]
> > >
> > > kexec mailing list
> > > [e-mail]
> > > http://lists.fedoraproject.org/admin/lists/[e-mail]
>
> kexec mailing list
> [e-mail]
> http://lists.fedoraproject.org/admin/lists/[e-mail]

[Baoquan He]

Hi network experts,

We got confusion on network DNS handling when we try to fix a kdump
bug. For better representation let's assume a network interface enp0s25
with static DNS setting in ifcfg-enp0s25 as "DNS1=8.8.8.8", and dhclient
privides 2 DNS server ip:

10.72.17.5
    10.68.5.26

Now the confusion is:

1) In 1st kernel if NetworkManager take control of the network setup and
PEERDNS=yes, the behaviour of DNS handling is that it adds dhclient's DNS
firstly then add static DNS from ifcfg-enp0s25. The result of
/etc/resolv.conf will be as follows:
       nameserver 10.72.17.5
       nameserver 10.68.5.26
       nameserver 8.8.8.8

- But if we set PEERDNS=no, the result of /etc/resolv.conf is:
       nameserver 8.8.8.8
    Apprently "PEERDNS=no" doesn't allow dhclient to add its DNS into
    /etc/resolv.conf.

2) However in 1st kernel if NetworkManager is disabled, means scripts
under /etc/sysconfig/network-scripts/ take control of network setup and
PEERDNS=yes, its behaviour is much different with NetworkManager. It
will firstly add dhclient's DNS, then replace the first entry, namely
"10.72.17.5" with the found static DNS from ifcfg-enp0s25. The result of
/etc/resolv.conf will be like:
       nameserver 8.8.8.8
       nameserver 10.68.5.26

- If PEERDNS=no set in ifcfg-enp0s25
     /etc/resolv.conf won't be changed at all.

Using NetworkManager or not using it can bring us so different
behaviours and different /etc/resolv.conf. Could you give suggestion how
we can make decision to choose a reasonable one since kdump probablly
need to cope with both of them?

In fact above cases are not problems we have since dracut have another
different rules then above, and we need handle it. But now we need to
clarify how DNS handling acts in 1st kernel. Your suggestions and ideas
are very precisous to us.

Thanks
Baoquan

On 04/25/16 at 03:29pm, Xunlei Pang wrote:
> ============= 3. Conclusion =============
> Dracut, network-manager, and "network-scripts" all have different hehavior
> in handling DNS.
>
> As a dhcp example:
> Suppose enp0s25, the dhcped DNSes are stable: 10.72.17.5 and 10.68.5.26
>
> In ifcfg-enp0s25:
> DNS1: 8.8.8.8
>
> For 1st kernel's network-manager, the final nameservers in /etc/resolv.conf
> -) If PEERDNS=yes(default is yes if PEERDNS doesn't exist) in ifcfg-enp0s25
>     nameserver 10.72.17.5
>     nameserver 10.68.5.26
>     nameserver 8.8.8.8
> -) If PEERDNS=no in ifcfg-enp0s25
>     nameserver 10.72.17.5
>     nameserver 10.68.5.26
>     nameserver 8.8.8.8
>
> For 1st kernel's scripts under /etc/sysconfig/network-scripts/ without network-manager
> -) If PEERDNS=yes in ifcfg-enp0s25
>     nameserver 8.8.8.8
>     nameserver 10.68.5.26
> -) If PEERDNS=no in ifcfg-enp0s25
>     Not touch /etc/resolv.conf
>     (i.e. /etc/resolv.conf is left unchanged as that before calling "ifup <config>")
>
> For dracut in latest fedora kexec-tools(1st kernel using network-manager)
> "${initdir}/etc/cmdline.d/42dns.conf" will contain:
>     nameserver=8.8.8.8
>     nameserver=10.72.17.5
>     nameserver=10.68.5.26
>     nameserver=8.8.8.8
>
> -) If "rd.peerdns=1"(default is "1" if "rd.peerdns" doesn't exist) is passed which is the default case
>     nameserver 8.8.8.8
>     nameserver 10.72.17.5
>     nameserver 10.68.5.26
>     nameserver 8.8.8.8
>     nameserver 10.72.17.5 // the last two are drauct' dhcp generated items
>     nameserver 10.68.5.26
> -) If "rd.peerdns=0" is passed
>     nameserver 8.8.8.8
>     nameserver 10.72.17.5
>     nameserver 10.68.5.26
>     nameserver 8.8.8.8
>
> Regards,
> Xunlei
> > > Regards,
> > > Xunlei
> > > > Regards,
> > > > Xunlei
> > > > > Thanks
> > > > > Minfei
> > > > > > There are two issues by doing this:
> > > > > > The dns sequence is different from that in 1st system.
> > > > > > There are some duplicated items.
> > > > > > NOTE: kdump_setup_dns() meant to avoid the duplication,
> > > > > > but the original shell command is actually disfunctional:
> > > > > > "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)
> > > > > >
> > > > > > Fix the issues by firstly parsing "/etc/resolv.conf", then
> > > > > > parsing ifcfg file, finally delete the duplicated items.
> > > > > > Signed-off-by: Xunlei Pang
> > > > > >
> > > > > > dracut-module-setup.sh | 27 ++++++++++++++++-----------
> > > > > >  1 file changed, 16 insertions(+), 11 deletions(-)
> > > > > >
> > > > > > diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> > > > > > index 350864e..b7763f7 100755
> > > > > > --- a/dracut-module-setup.sh
> > > > > > +++ b/dracut-module-setup.sh
> > > > > > @@ -68,14 +68,6 @@ kdump_setup_dns() {
> > > > > >      local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
> > > > > >      local ifcfg_file
> > > > > > ifcfg_file=$(get_ifcfg_filename $1)
> > > > > > if [ -f "${ifcfg_file}" ]; then
> > > > > >    . ${ifcfg_file}
> > > > > > fi
> > > > > > [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
> > > > > > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > > > > > while read content;
> > > > > >    do
> > > > > >        _nameserver=$(echo $content | grep ^nameserver)
> > > > > >
> > > > > > @@ -84,10 +76,23 @@ kdump_setup_dns() {
> > > > > >          _dns=$(echo $_nameserver | cut -d' ' -f2)
> > > > > >          [ -z "$_dns" ] && continue
> > > > > >    if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
> > > > > >        echo "nameserver=$_dns" >> "$_dnsfile"
> > > > > >    fi
> > > > > >    echo "nameserver=$_dns" >> "$_dnsfile"
> > > > > > done < "/etc/resolv.conf"
> > > > > > unset DNS1 DNS2
> > > > > > ifcfg_file=$(get_ifcfg_filename $1)
> > > > > > if [ -f "${ifcfg_file}" ]; then
> > > > > >    . ${ifcfg_file}
> > > > > > fi
> > > > > > [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
> > > > > > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > > > > > # Delete duplicated lines
> > > > > > if [ -f "$_dnsfile" ]; then
> > > > > >    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
> > > > > >    mv -f $_dnsfile.tmp $_dnsfile
> > > > > > fi
> > > > > >
> > > > > > }
> > > > > > #$1: netdev name
> > > > > >
> > > > > > 1.8.3.1
> > > > > > _______________________________________________
> > > > > > kexec mailing list
> > > > > > [e-mail]
> > > > > > http://lists.fedoraproject.org/admin/lists/[e-mail]
> > > >
> > > > kexec mailing list
> > > > [e-mail]
> > > > http://lists.fedoraproject.org/admin/lists/[e-mail]
> > >
> > > kexec mailing list
> > > [e-mail]
> > > http://lists.fedoraproject.org/admin/lists/[e-mail]

[Xunlei Pang]

On 2016/04/22 at 16:58, Minfei Huang wrote:
> On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> > Current implementation of kdump_setup_dns() get the dns
> > from interface's ifcfg file first, then parse those in
> > "/etc/resolv.conf". For example, DNS1 in ifcfg file along
> > with dhcp, the final dns(/etc/resolv.conf) in 1st system
> > will be like(dhcp first, then ifcfg file appending end):
> >     dhcp dns1
> >     dhcp dns2
> >     dhcp dns3
> >     DNS1 in ifcfg
> >
> > After parsing, the dns(/etc/cmdline.d/42dns.conf) in kdump
> > system will be like:
> >     DNS1 in ifcfg
> >     dhcp dns1
> >     dhcp dns2
> >     dhcp dns3
> >     DNS1 in ifcfg
>
> Hi.
>
> I have some confusion about the dns order in /etc/resolv.conf. From my
> test, I found that dns client would append DNS entry to /etc/resolv.conf
> in kdump kernel. Following is my test result.
>
> kdump:/# cat /sysroot/etc/resolv.conf
> # Generated by NetworkManager
> search nay.redhat.com redhat.com
> nameserver 10.72.17.5
> nameserver 10.68.5.26
> nameserver 192.168.122.1
> nameserver 8.8.8.8
>
> kdump:/# cat /etc/resolv.conf
> nameserver 10.72.17.5
> nameserver 10.68.5.26
> nameserver 192.168.122.1
> nameserver 8.8.8.8
> nameserver 192.168.122.1
>
> The last dns entry "nameserver 192.168.122.1" is appended in kdump
> kernel by DNS client. So the order may be like this:
> dhcp dns1
> DNS1
> dhcp dns1

Actually, I think we can safely remove the ifcfg part, since we are using "/etc/resolv.conf" directly which
was correctly parsed by the first system.

Regards,
Xunlei
> Thanks
> Minfei
> > There are two issues by doing this:
> > The dns sequence is different from that in 1st system.
> > There are some duplicated items.
> > NOTE: kdump_setup_dns() meant to avoid the duplication,
> > but the original shell command is actually disfunctional:
> > "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)
> >
> > Fix the issues by firstly parsing "/etc/resolv.conf", then
> > parsing ifcfg file, finally delete the duplicated items.
> > Signed-off-by: Xunlei Pang
> >
> > dracut-module-setup.sh | 27 ++++++++++++++++-----------
> >  1 file changed, 16 insertions(+), 11 deletions(-)
> >
> > diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> > index 350864e..b7763f7 100755
> > --- a/dracut-module-setup.sh
> > +++ b/dracut-module-setup.sh
> > @@ -68,14 +68,6 @@ kdump_setup_dns() {
> >      local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
> >      local ifcfg_file
> > ifcfg_file=$(get_ifcfg_filename $1)
> > if [ -f "${ifcfg_file}" ]; then
> >    . ${ifcfg_file}
> > fi
> > [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
> > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > while read content;
> >    do
> >        _nameserver=$(echo $content | grep ^nameserver)
> >
> > @@ -84,10 +76,23 @@ kdump_setup_dns() {
> >          _dns=$(echo $_nameserver | cut -d' ' -f2)
> >          [ -z "$_dns" ] && continue
> >    if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
> >        echo "nameserver=$_dns" >> "$_dnsfile"
> >    fi
> >    echo "nameserver=$_dns" >> "$_dnsfile"
> > done < "/etc/resolv.conf"
> > unset DNS1 DNS2
> > ifcfg_file=$(get_ifcfg_filename $1)
> > if [ -f "${ifcfg_file}" ]; then
> >    . ${ifcfg_file}
> > fi
> > [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
> > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > # Delete duplicated lines
> > if [ -f "$_dnsfile" ]; then
> >    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
> >    mv -f $_dnsfile.tmp $_dnsfile
> > fi
> >
> > }
> > #$1: netdev name
> >
> > 1.8.3.1
> > _______________________________________________
> > kexec mailing list
> > [e-mail]
> > http://lists.fedoraproject.org/admin/lists/[e-mail]

[Minfei Huang]

On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> # Delete duplicated lines
> if [ -f "$_dnsfile" ]; then
>    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp

Hi.

Maybe storing the temporary file to ${initdir}/tmp/ is better. You can
refer to function kdump_install_conf.

Thanks
Minfei

[Xunlei Pang]

On 2016/04/22 at 17:09, Minfei Huang wrote:
> On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> > # Delete duplicated lines
> > if [ -f "$_dnsfile" ]; then
> >    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
>
> Hi.
>
> Maybe storing the temporary file to ${initdir}/tmp/ is better. You can
> refer to function kdump_install_conf.

This is better, will do

Regards,
Xunlei
> Thanks
> Minfei

[Minfei Huang]

On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> There are two issues by doing this:
> The dns sequence is different from that in 1st system.
> There are some duplicated items.
> NOTE: kdump_setup_dns() meant to avoid the duplication,
> but the original shell command is actually disfunctional:
> "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)

Hi.

This test is useful in previous context, since there may be duplicate
DNS entries in /etc/resolv.conf. It is safe to remove it in your patch,
because the deplicate DNS entries will be remove later.

Thanks
Minfei
> Fix the issues by firstly parsing "/etc/resolv.conf", then
> parsing ifcfg file, finally delete the duplicated items.
> Signed-off-by: Xunlei Pang
>
> dracut-module-setup.sh | 27 ++++++++++++++++-----------
>  1 file changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> index 350864e..b7763f7 100755
> --- a/dracut-module-setup.sh
> +++ b/dracut-module-setup.sh
> @@ -68,14 +68,6 @@ kdump_setup_dns() {
>      local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
>      local ifcfg_file
> ifcfg_file=$(get_ifcfg_filename $1)
> if [ -f "${ifcfg_file}" ]; then
>    . ${ifcfg_file}
> fi
> [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
> [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> while read content;
>    do
>        _nameserver=$(echo $content | grep ^nameserver)
>
> @@ -84,10 +76,23 @@ kdump_setup_dns() {
>          _dns=$(echo $_nameserver | cut -d' ' -f2)
>          [ -z "$_dns" ] && continue
>    if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
>        echo "nameserver=$_dns" >> "$_dnsfile"
>    fi
>    echo "nameserver=$_dns" >> "$_dnsfile"
> done < "/etc/resolv.conf"
> unset DNS1 DNS2
> ifcfg_file=$(get_ifcfg_filename $1)
> if [ -f "${ifcfg_file}" ]; then
>    . ${ifcfg_file}
> fi
> [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
> [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> # Delete duplicated lines
> if [ -f "$_dnsfile" ]; then
>    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
>    mv -f $_dnsfile.tmp $_dnsfile
> fi
>
> }
> #$1: netdev name
>
> 1.8.3.1
> _______________________________________________
> kexec mailing list
> [e-mail]
> http://lists.fedoraproject.org/admin/lists/[e-mail]

[Xunlei Pang]

On 2016/04/22 at 17:26, Minfei Huang wrote:
> On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> > There are two issues by doing this:
> > The dns sequence is different from that in 1st system.
> > There are some duplicated items.
> > NOTE: kdump_setup_dns() meant to avoid the duplication,
> > but the original shell command is actually disfunctional:
> > "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)
>
> Hi.
>
> This test is useful in previous context, since there may be duplicate
> DNS entries in /etc/resolv.conf. It is safe to remove it in your patch,
> because the deplicate DNS entries will be remove later.

Actually, this condition always returns true, you can test it :-)

Regards,
Xunlei
> Thanks
> Minfei
> > Fix the issues by firstly parsing "/etc/resolv.conf", then
> > parsing ifcfg file, finally delete the duplicated items.
> > Signed-off-by: Xunlei Pang
> >
> > dracut-module-setup.sh | 27 ++++++++++++++++-----------
> >  1 file changed, 16 insertions(+), 11 deletions(-)
> >
> > diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> > index 350864e..b7763f7 100755
> > --- a/dracut-module-setup.sh
> > +++ b/dracut-module-setup.sh
> > @@ -68,14 +68,6 @@ kdump_setup_dns() {
> >      local _dnsfile=${initdir}/etc/cmdline.d/42dns.conf
> >      local ifcfg_file
> > ifcfg_file=$(get_ifcfg_filename $1)
> > if [ -f "${ifcfg_file}" ]; then
> >    . ${ifcfg_file}
> > fi
> > [ -n "$DNS1" ] && echo "nameserver=$DNS1" > "$_dnsfile"
> > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > while read content;
> >    do
> >        _nameserver=$(echo $content | grep ^nameserver)
> >
> > @@ -84,10 +76,23 @@ kdump_setup_dns() {
> >          _dns=$(echo $_nameserver | cut -d' ' -f2)
> >          [ -z "$_dns" ] && continue
> >    if [ ! -f $_dnsfile ] || [ ! $(cat $_dnsfile | grep -q $_dns) ]; then
> >        echo "nameserver=$_dns" >> "$_dnsfile"
> >    fi
> >    echo "nameserver=$_dns" >> "$_dnsfile"
> > done < "/etc/resolv.conf"
> > unset DNS1 DNS2
> > ifcfg_file=$(get_ifcfg_filename $1)
> > if [ -f "${ifcfg_file}" ]; then
> >    . ${ifcfg_file}
> > fi
> > [ -n "$DNS1" ] && echo "nameserver=$DNS1" >> "$_dnsfile"
> > [ -n "$DNS2" ] && echo "nameserver=$DNS2" >> "$_dnsfile"
> > # Delete duplicated lines
> > if [ -f "$_dnsfile" ]; then
> >    awk '!a[$0]++' $_dnsfile > $_dnsfile.tmp
> >    mv -f $_dnsfile.tmp $_dnsfile
> > fi
> >
> > }
> > #$1: netdev name
> >
> > 1.8.3.1
> > _______________________________________________
> > kexec mailing list
> > [e-mail]
> > http://lists.fedoraproject.org/admin/lists/[e-mail]

[Minfei Huang]

On 04/22/16 at 10:54pm, Xunlei Pang wrote:
> On 2016/04/22 at 17:26, Minfei Huang wrote:
> > On 04/21/16 at 03:44pm, Xunlei Pang wrote:
> > > There are two issues by doing this:
> > > The dns sequence is different from that in 1st system.
> > > There are some duplicated items.
> > > NOTE: kdump_setup_dns() meant to avoid the duplication,
> > > but the original shell command is actually disfunctional:
> > > "[ ! $(cat $_dnsfile | grep -q $_dns) ]" (always true)
> >
> > Hi.
> >
> > This test is useful in previous context, since there may be duplicate
> > DNS entries in /etc/resolv.conf. It is safe to remove it in your patch,
> > because the deplicate DNS entries will be remove later.
>
> Actually, this condition always returns true, you can test it :-)

Thanks for pointing it out.

This error is caused by misusing brackets. Removing this brackets can
make this test work. It's lucky that kdump can work as well, although
there are duplicate DNS entry in resolv.conf.

Thanks
Minfei