Merge pull request #7103 from vrutkovs/origin-dns-prepend-cluster-local

Automatic merge from submit-queue.

origin-dns: make sure cluster.local DNS server is listed first

This would ensure glibc resolver won't discard this server when existing
DNS server list is longer than 2.
This sed would also update existing configuration, where cluster.local
was appended

Fixes bug https://bugzilla.redhat.com/show_bug.cgi?id=1544001

roles/openshift_node/files/networkmanager/99-origin-dns.sh

@@ -116,8 +116,9 @@ EOF
       echo "nameserver "${def_route_ip}"" >> ${NEW_RESOLV_CONF}
       if ! grep -qw search ${NEW_RESOLV_CONF}; then
         echo 'search cluster.local' >> ${NEW_RESOLV_CONF}
-      elif ! grep -q 'search.*cluster.local' ${NEW_RESOLV_CONF}; then
-        sed -i '/^search/ s/$/ cluster.local/' ${NEW_RESOLV_CONF}
+      elif ! grep -q 'search cluster.local' ${NEW_RESOLV_CONF}; then
+        # cluster.local should be in first three DNS names so that glibc resolver would work
+        sed -i -e 's/^search \(.\+\)\( cluster\.local\)\{0,1\}$/search cluster.local \1/' ${NEW_RESOLV_CONF}
       fi
       cp -Z ${NEW_RESOLV_CONF} /etc/resolv.conf
     fi