dnsmasq: add script for dynamic DNS updates

roles/dnsmasq/tasks/main.yml

@@ -2,6 +2,32 @@
   package:
     name:
     - dnsmasq
+    - bind-tools
+    - krb5
+    - py3-pexpect
+
+- name: Configure kerberos
+  template:
+    dest: /etc/krb5.conf
+    src: krb5.conf.j2
+
+- name: Init kerberos keytab
+  expect:
+    command: ktutil
+    responses:
+      '.*:':
+      - 'add_entry -password -p {{ password.ldap_user }} -k 1 -e aes256-cts-hmac-sha1-96'
+      - '{{ password.ldap_pass }}'
+      - 'write_kt /etc/krb5.keytab'
+      - 'exit'
+  args:
+    creates: /etc/krb5.keytab
+
+- name: Copy DNS updater script
+  template:
+    dest: "/usr/local/bin/dns-update"
+    src: "dns-update.j2"
+    mode: 0700
 
 - name: Configure dnsmasq
   template:
@@ -12,5 +38,4 @@
   - 10-ranges.conf
   notify: restart dnsmasq
 
-# TODO DNS update
 # TODO netboot config

roles/dnsmasq/templates/00-options.conf.j2

@@ -9,3 +9,5 @@ dhcp-proxy
 
 dhcp-option = option:dns-server,{{ dns | join(',') }}
 dhcp-option = option:ntp-server,{{ ntp | join(',') }}
+
+dhcp-script = /usr/local/bin/dns-update

roles/dnsmasq/templates/dns-update.j2

@@ -0,0 +1,29 @@
+#!/bin/sh
+
+domain={{ domain }}
+ldap_user={{ password.ldap_user }}
+ttl=3600
+
+address="${3}"
+
+case "${1}" in
+add)
+	host="${4}"
+	kinit -k "${ldap_user}"
+	nsupdate -g <<EOF
+update add ${host}.${domain} ${ttl} A ${address}
+send
+EOF
+	;;
+old)
+	if [ -n "${DNSMASQ_OLD_HOSTNAME}" -a -n "${DNSMASQ_SUPPLIED_HOSTNAME}" ] ; then
+		kinit -k "${ldap_user}"
+		nsupdate -g <<EOF
+update del ${DNSMASQ_OLD_HOSTNAME}.${domain}
+update add ${DNSMASQ_SUPPLIED_HOSTNAME}.${domain} ${ttl} A ${address}
+send
+EOF
+	fi
+	;;
+# TODO del, probably
+esac

roles/dnsmasq/templates/krb5.conf.j2

@@ -0,0 +1,18 @@
+[libdefaults]
+dns_lookup_realm = false
+ticket_lifetime = 24h
+renew_lifetime = 7d
+#forwardable = true
+rdns = false
+default_realm = {{ domain | upper }}
+
+[realms]
+{{ domain | upper }} = {
+{% for server in dns %}
+  kdc = {{ server }}
+{% endfor %}
+}
+
+[domain_realm]
+.{{ domain }} = {{ domain | upper }}
+{{ domain }} = {{ domain | upper }}