Simplify dns management

This relies on the node service configuring dnsmasq for all the zones
that the node should be responsible via dbus.

This removes all install time node specific configuration as well.

Author: sdodson

roles/openshift_node/templates/node.service.j2

@@ -14,10 +14,6 @@ After=dnsmasq.service
 Type=notify
 EnvironmentFile=/etc/sysconfig/{{ openshift.common.service_type }}-node
 Environment=GOTRACEBACK=crash
-ExecStartPre=/usr/bin/cp /etc/origin/node/node-dnsmasq.conf /etc/dnsmasq.d/
-ExecStartPre=/usr/bin/dbus-send --system --dest=uk.org.thekelleys.dnsmasq /uk/org/thekelleys/dnsmasq uk.org.thekelleys.SetDomainServers array:string:/in-addr.arpa/127.0.0.1,/{{ openshift.common.dns_domain }}/127.0.0.1
-ExecStopPost=/usr/bin/rm /etc/dnsmasq.d/node-dnsmasq.conf
-ExecStopPost=/usr/bin/dbus-send --system --dest=uk.org.thekelleys.dnsmasq /uk/org/thekelleys/dnsmasq uk.org.thekelleys.SetDomainServers array:string:
 ExecStart=/usr/bin/openshift start node --config=${CONFIG_FILE} $OPTIONS
 LimitNOFILE=65536
 LimitCORE=infinity

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

@@ -9,8 +9,6 @@
 # a pod would fail.
 #
 # To use this,
-# - If this host is also a master, reconfigure master dnsConfig to listen on
-#   8053 to avoid conflicts on port 53 and open port 8053 in the firewall
 # - Drop this script in /etc/NetworkManager/dispatcher.d/
 # - systemctl restart NetworkManager
 # - Configure node-config.yaml to set dnsIP: to the ip address of this
@@ -29,16 +27,8 @@ cd /etc/sysconfig/network-scripts
 [ -f ../network ] && . ../network
 
 if [[ $2 =~ ^(up|dhcp4-change|dhcp6-change)$ ]]; then
-  # If the origin-upstream-dns config file changed we need to restart
   NEEDS_RESTART=0
-  UPSTREAM_DNS='/etc/dnsmasq.d/origin-upstream-dns.conf'
-  # We'll regenerate the dnsmasq origin config in a temp file first
-  UPSTREAM_DNS_TMP=`mktemp`
-  UPSTREAM_DNS_TMP_SORTED=`mktemp`
-  CURRENT_UPSTREAM_DNS_SORTED=`mktemp`
   NEW_RESOLV_CONF=`mktemp`
-  NEW_NODE_RESOLV_CONF=`mktemp`
-
 
   ######################################################################
   # couldn't find an existing method to determine if the interface owns the
@@ -49,52 +39,18 @@ if [[ $2 =~ ^(up|dhcp4-change|dhcp6-change)$ ]]; then
   if [[ ${DEVICE_IFACE} == ${def_route_int} ]]; then
     if [ ! -f /etc/dnsmasq.d/origin-dns.conf ]; then
       cat << EOF > /etc/dnsmasq.d/origin-dns.conf
-no-resolv
 domain-needed
-server=/cluster.local/172.30.0.1
-server=/30.172.in-addr.arpa/172.30.0.1
 enable-dbus
+bind-dynamic
+except-interface=lo
+dns-loop-detect
+resolv-file=/etc/origin/node/resolv.conf
 EOF
       # New config file, must restart
       NEEDS_RESTART=1
     fi
 
-    # If network manager doesn't know about the nameservers then the best
-    # we can do is grab them from /etc/resolv.conf but only if we've got no
-    # watermark
-    if ! grep -q '99-origin-dns.sh' /etc/resolv.conf; then
-      if [[ -z "${IP4_NAMESERVERS}" || "${IP4_NAMESERVERS}" == "${def_route_ip}" ]]; then
-            IP4_NAMESERVERS=`grep '^nameserver ' /etc/resolv.conf | awk '{ print $2 }'`
-      fi
-      ######################################################################
-      # Write out default nameservers for /etc/dnsmasq.d/origin-upstream-dns.conf
-      # and /etc/origin/node/resolv.conf in their respective formats
-      for ns in ${IP4_NAMESERVERS}; do
-        if [[ ! -z $ns ]]; then
-          echo "server=${ns}" >> $UPSTREAM_DNS_TMP
-          echo "nameserver ${ns}" >> $NEW_NODE_RESOLV_CONF
-        fi
-      done
-      # Sort it in case DNS servers arrived in a different order
-      sort $UPSTREAM_DNS_TMP > $UPSTREAM_DNS_TMP_SORTED
-      sort $UPSTREAM_DNS > $CURRENT_UPSTREAM_DNS_SORTED
-      # Compare to the current config file (sorted)
-      NEW_DNS_SUM=`md5sum ${UPSTREAM_DNS_TMP_SORTED} | awk '{print $1}'`
-      CURRENT_DNS_SUM=`md5sum ${CURRENT_UPSTREAM_DNS_SORTED} | awk '{print $1}'`
-      if [ "${NEW_DNS_SUM}" != "${CURRENT_DNS_SUM}" ]; then
-        # DNS has changed, copy the temp file to the proper location (-Z
-        # sets default selinux context) and set the restart flag
-        cp -Z $UPSTREAM_DNS_TMP $UPSTREAM_DNS
-        NEEDS_RESTART=1
-      fi
-      # compare /etc/origin/node/resolv.conf checksum and replace it if different
-      NEW_NODE_RESOLV_CONF_MD5=`md5sum ${NEW_NODE_RESOLV_CONF}`
-      OLD_NODE_RESOLV_CONF_MD5=`md5sum /etc/origin/node/resolv.conf`
-      if [ "${NEW_NODE_RESOLV_CONF_MD5}" != "${OLD_NODE_RESOLV_CONF_MD5}" ]; then
-        cp -Z $NEW_NODE_RESOLV_CONF /etc/origin/node/resolv.conf
-      fi
-    fi
-
+    # dnsmasq not running, needs a restart
     if ! `systemctl -q is-active dnsmasq.service`; then
       NEEDS_RESTART=1
     fi
@@ -103,6 +59,10 @@ EOF
     if [ "${NEEDS_RESTART}" -eq "1" ]; then
       systemctl restart dnsmasq
     fi
+    
+    if [ ! -f /etc/origin/node/resolv.conf ]; then
+      cp /etc/resolv.conf /etc/origin/node/resolv.conf
+    fi
 
     # Only if dnsmasq is running properly make it our only nameserver and place
     # a watermark on /etc/resolv.conf
@@ -122,5 +82,5 @@ EOF
   fi
 
   # Clean up after yourself
-  rm -f $UPSTREAM_DNS_TMP $UPSTREAM_DNS_TMP_SORTED $CURRENT_UPSTREAM_DNS_SORTED $NEW_RESOLV_CONF
+  rm -f $NEW_RESOLV_CONF
 fi

roles/openshift_node_dnsmasq/tasks/main.yml

@@ -14,33 +14,15 @@
   package: name=dnsmasq state=installed
   when: not openshift.common.is_atomic | bool
 
-- name: ensure origin/node directory exists
+- name: Remove older dnsmasq configuration files
   file:
-    state: directory
     path: "{{ item }}"
-    owner: root
-    group: root
-    mode: '0700'
+    state: absent
   with_items:
-  - /etc/origin
-  - /etc/origin/node
-
-# this file is copied to /etc/dnsmasq.d/ when the node starts and is removed
-# when the node stops. A dbus-message is sent to dnsmasq to add the same entries
-# so that dnsmasq doesn't need to be restarted. Once we can use dnsmasq 2.77 or
-# newer we can use --server-file option to update the servers dynamically and
-# reload them by sending dnsmasq a SIGHUP. We write the file in case someone else
-# triggers a restart of dnsmasq but not a node restart.
-- name: Install node-dnsmasq.conf
-  template:
-    src: node-dnsmasq.conf.j2
-    dest: /etc/origin/node/node-dnsmasq.conf
-
-- name: Install dnsmasq configuration
-  template:
-    src: origin-dns.conf.j2
-    dest: /etc/dnsmasq.d/origin-dns.conf
-  notify: restart dnsmasq
+    - "/etc/dnsmasq.d/origin-upstream-dns.conf"
+    - "/etc/dnsmasq.d/node-dnsmasq.conf"
+    - "/etc/dnsmasq.d/origin-dns.conf"
+  when: openshift.common.version_gte_3_7 | bool
 
 - name: Deploy additional dnsmasq.conf
   template: