Use Dom0's resolv.conf unless nameserver is set.

If nameserver config option is not set (default value), copy Dom0's
/etc/resolv.conf on guest.
Provide a role to show how to customize /etc/resolv.conf in guest.

bin/xen-create-image

@@ -237,6 +237,8 @@ xen-create-image - Easily create new Xen instances with networking and OpenSSH.
    --nameserver="123.456.789.ABC 123.456.789.DEF"
                 Setup the nameserver of the machine, multiple space
                 separated nameservers are allowed.
+                If not provided, Dom0's /etc/resolv.conf will be copied
+                to guest.
 
    --bridge=brname
                 Optionally, set a specific bridge for the new instance.
@@ -377,7 +379,6 @@ Create a Xen configuration file in so that xm can start the new domain.
   gateway    = 192.168.1.1
   broadcast  = 192.168.1.255
   netmask    = 255.255.255.0
-  nameserver = 192.168.1.1
 
 
   #
@@ -1407,6 +1408,11 @@ sub setupDefaultOptions
     $CONFIG{ 'mount_fs_xfs' }      = '-t xfs';
     $CONFIG{ 'mount_fs_reiserfs' } = '-t reiserfs';
 
+    #
+    #  Network options.
+    #
+    $CONFIG{ 'nameserver' } = '';
+
 }
 
 

etc/xen-tools.conf

@@ -163,12 +163,21 @@ image  = sparse   # Specify sparse vs. full disk images.
 # gateway    = 192.168.1.1
 # netmask    = 255.255.255.0
 # broadcast  = 192.168.1.255
-# nameserver = 192.168.1.1
 #
 # Uncomment this if you wish the images to use DHCP
 #
 # dhcp = 1
 
+#
+# Uncomment and adjust this setting if you wish to give your new
+# instances a specific nameserver.
+#
+# By default, nameserver is not set, and Dom0's /etc/resolv.conf will
+# be copied to guest.
+#
+# nameserver = 192.168.1.1
+#
+
 #
 # Setup bridge name for host vif. Usefull if you use bridged networking
 # for guests.

hooks/centos-4/40-setup-networking

@@ -83,6 +83,8 @@ E_O_STATIC
         for ns in $nameserver; do
             echo "nameserver $ns" >>${prefix}/etc/resolv.conf.old
         done
+    else
+        cp /etc/resolv.conf ${prefix}/etc/resolv.conf.old
     fi
 else
     cat <<E_O_DHCP >${prefix}/etc/sysconfig/network-scripts/ifcfg-eth0

hooks/centos-5/40-setup-networking

@@ -83,6 +83,8 @@ E_O_STATIC
         for ns in $nameserver; do
             echo "nameserver $ns" >>${prefix}/etc/resolv.conf.old
         done
+    else
+        cp /etc/resolv.conf ${prefix}/etc/resolv.conf.old
     fi
 else
     cat <<E_O_DHCP >${prefix}/etc/sysconfig/network-scripts/ifcfg-eth0

hooks/dapper/40-setup-networking

@@ -123,6 +123,8 @@ E_O_STATIC
         for ns in $nameserver; do
             echo "nameserver $ns" >>${prefix}/etc/resolv.conf.old
         done
+    else
+        cp /etc/resolv.conf ${prefix}/etc/resolv.conf.old
     fi
 }
 

hooks/debian/40-setup-networking

@@ -143,6 +143,8 @@ E_O_STATIC
         for ns in $nameserver; do
             echo "nameserver $ns" >>${prefix}/etc/resolv.conf.old
         done
+    else
+        cp /etc/resolv.conf ${prefix}/etc/resolv.conf.old
     fi
 }
 

hooks/edgy/40-setup-networking

@@ -132,6 +132,8 @@ E_O_STATIC
         for ns in $nameserver; do
             echo "nameserver $ns" >>${prefix}/etc/resolv.conf.old
         done
+    else
+        cp /etc/resolv.conf ${prefix}/etc/resolv.conf.old
     fi
 }
 

hooks/fedora-core-6/40-setup-networking

@@ -83,6 +83,8 @@ E_O_STATIC
         for ns in $nameserver; do
             echo "nameserver $ns" >>${prefix}/etc/resolv.conf.old
         done
+    else
+        cp /etc/resolv.conf ${prefix}/etc/resolv.conf.old
     fi
 else
     cat <<E_O_DHCP >${prefix}/etc/sysconfig/network-scripts/ifcfg-eth0

hooks/gentoo/40-setup-networking

@@ -107,6 +107,8 @@ E_O_STATIC
         for ns in $nameserver; do
             echo "nameserver $ns" >>${prefix}/etc/resolv.conf.old
         done
+    else
+        cp /etc/resolv.conf ${prefix}/etc/resolv.conf.old
     fi
 }
 

hooks/intrepid/40-setup-networking

@@ -132,6 +132,8 @@ E_O_STATIC
         for ns in $nameserver; do
             echo "nameserver $ns" >>${prefix}/etc/resolv.conf.old
         done
+    else
+        cp /etc/resolv.conf ${prefix}/etc/resolv.conf.old
     fi
 }
 

hooks/karmic/40-setup-networking

@@ -132,6 +132,8 @@ E_O_STATIC
         for ns in $nameserver; do
             echo "nameserver $ns" >>${prefix}/etc/resolv.conf.old
         done
+    else
+        cp /etc/resolv.conf ${prefix}/etc/resolv.conf.old
     fi
 }
 

roles/resolv

@@ -0,0 +1,44 @@
+#!/bin/sh
+#
+#  This role helps to customize guest's /etc/resolv.conf
+#
+
+prefix=$1
+
+#
+#  Source our common functions - this will let us install a Debian package.
+#
+if [ -e /usr/lib/xen-tools/common.sh ]; then
+    . /usr/lib/xen-tools/common.sh
+else
+    echo "Installation problem"
+fi
+
+
+#
+# Log our start
+#
+logMessage Script $0 starting
+
+
+#
+# WARNING :
+#
+# resolv.conf is backed up as resolv.conf.old during roles execution to
+# permit the chrooted guest to be able to resolve during installation.
+# Use resolv.conf.old name during hooks, it will be correctly renamed
+# after hooks execution
+#
+
+#
+# Create Guest's resolv.conf as resolv.conf.old (see WARNING before) :
+#
+cat <<RESOLV_CONF_EOF >${prefix}/etc/resolv.conf.old
+nameserver 192.168.1.1
+#search domain.tld
+RESOLV_CONF_EOF
+
+#
+#  Log our finish
+#
+logMessage Script $0 finished