Reorganize DHCP options

- 'dhcpd_global_options' text block has been split into individual
  variables;

- if list of nameservers is not specified, debops.dhcpd role will
  advertise nameservers set in '/etc/resolv.conf' file;

- default set of options can be enabled or disabled using a bool
  variable 'dhcpd_auto_options'. The options have been moved to
  a separate configuration template included in main one;

defaults/main.yml

@@ -76,6 +76,12 @@ dhcpd_server_options: '{{ "-" + dhcpd_ipversion }}'
 dhcpd_authoritative: False
 
 
+# .. envvar:: dhcpd_log_facility
+#
+# Log facility to use
+dhcpd_log_facility: 'local7'
+
+
 # .. envvar:: dhcpd_interfaces
 #
 # List of network interfaces to listen on for DHCP requests
@@ -84,40 +90,58 @@ dhcpd_authoritative: False
 dhcpd_interfaces: []
 
 
-# .. envvar:: dhcpd_domain
-#
-# Default domain to use
-dhcpd_domain: '{{ ansible_domain }}'
-
-
-# .. envvar:: dhcpd_dns_servers
-#
-# List of default DNS servers. By default, point users to the same host that
-# serves them DHCP requests, on default interface. If this host is a router,
-# you might need to set DNS server to internal interface IP address.
-dhcpd_dns_servers: [ '{{ ansible_default_ipv4.address }}' ]
-
-
 # .. envvar:: dhcpd_lease_time
 #
 # Max lease time in hours (default lease time is calculated below)
-dhcpd_lease_time: 24
+dhcpd_lease_time: '24'
 
 
-# .. envvar:: dhcpd_global_options
+# .. envvar:: dhcpd_global_default_lease_time
 #
-# Default global options formatted as a text block
-dhcpd_global_options: |
-  option domain-name "{{ ansible_domain }}";
-  option domain-name-servers {{ dhcpd_dns_servers | join(' ') }};
-  default-lease-time {{ (((dhcpd_lease_time / 2) + 6) * 60 * 60)|round|int }};
-  max-lease-time {{ (dhcpd_lease_time * 60 * 60)|round|int }};
-  log-facility local7;
+# Default lease time for all IP address leases (18 hours)
+dhcpd_global_default_lease_time: '{{ (((dhcpd_lease_time|int / 2) + 6) * 60 * 60)|round|int }}'
+
+
+# .. envvar:: dhcpd_global_max_lease_time
+#
+# Maximum lease time for all IP addresses (24 hours)
+dhcpd_global_max_lease_time: '{{ (dhcpd_lease_time|int * 60 * 60)|round|int }}'
+
+
+# ---------------------------
+#   DHCP advertised options
+# ---------------------------
+
+# .. envvar:: dhcpd_auto_options
+#
+# If enabled, ISC DHCP server will be configured with a set of automatically
+# detected options. See ``auto_options.j2`` template for more details.
+dhcpd_auto_options: True
+
+
+# .. envvar:: dhcpd_domain_name
+#
+# Default host domain to advertise
+dhcpd_domain_name: '{{ ansible_domain }}'
+
+
+# .. envvar:: dhcpd_domain_search
+#
+# List of additional domains which should be checked when looking for hostnames
+dhcpd_domain_search: []
+
+
+# .. envvar:: dhcpd_nameservers
+#
+# List of nameservers to advertise by default
+# If it's not specified, nameservers from ``/etc/resolv.conf`` will be used
+# instead.
+dhcpd_nameservers: []
 
 
 # .. envvar:: dhcpd_options
 #
-# Custom options formatted as a text block
+# Custom global options formatted as a text block
 dhcpd_options: False
 
 

tasks/main.yml

@@ -25,6 +25,17 @@
   notify: [ 'Restart isc-dhcp-relay' ]
   when: dhcpd_register_relay_debconf|d() and dhcpd_register_relay_debconf.changed
 
+- name: Get list of nameservers configured in /etc/resolv.conf
+  shell: grep -E '^nameserver\s' /etc/resolv.conf | awk '{print $2}' | sed -e 'N;s/\n/ /'
+  register: dhcpd_register_nameservers
+  changed_when: False
+  when: dhcpd_mode == 'server'
+
+- name: Convert list of nameservers to Ansible list
+  set_fact:
+    dhcpd_runtime_nameservers: "{{ dhcpd_register_nameservers.stdout.split(' ') }}"
+  when: (dhcpd_register_nameservers is defined and dhcpd_register_nameservers.stdout)
+
 - name: Configure DHCP server
   template:
     src: '{{ item }}.j2'

templates/etc/dhcp/auto_options.j2

@@ -0,0 +1,26 @@
+{% if dhcpd_domain_name|d() and dhcpd_domain_name %}
+option domain-name "{{ dhcpd_domain_name }}";
+
+{% endif %}
+{% if dhcpd_domain_search|d() and dhcpd_domain_search %}
+option domain-search "{{ dhcpd_domain_search | join('", "') }}";
+option dhcp6.domain-search "{{ dhcpd_domain_search | join('", "') }}";
+
+{% endif %}
+{% if dhcpd_nameservers|d() and dhcpd_nameservers %}
+{% set dhcpd_tpl_nameservers = dhcpd_nameservers %}
+{% elif dhcpd_runtime_nameservers|d() and dhcpd_runtime_nameservers %}
+{% set dhcpd_tpl_nameservers = dhcpd_runtime_nameservers %}
+{% endif %}
+{% if dhcpd_tpl_nameservers %}
+{% if dhcpd_tpl_nameservers | ipv4 %}
+option domain-name-servers {{ dhcpd_tpl_nameservers | ipv4 | join(", ") }};
+{% endif %}
+{% if dhcpd_tpl_nameservers | ipv6 %}
+option dhcp6.name-servers {{ dhcpd_tpl_nameservers | ipv6 | join(", ") }};
+{% endif %}
+
+{% endif %}
+{#
+    vim: ft=dhcpd
+#}

templates/etc/dhcp/dhcpd.conf.j2

@@ -8,10 +8,19 @@ authoritative;
 not authoritative;
 
 {% endif %}
-{% if dhcpd_global_options is defined and dhcpd_global_options %}
-# Global configuration options
-{{ dhcpd_global_options }}
+{% if dhcpd_global_default_lease_time|d() and dhcpd_global_default_lease_time %}
+default-lease-time {{ dhcpd_global_default_lease_time }};
+{% endif %}
+{% if dhcpd_global_max_lease_time|d() and dhcpd_global_max_lease_time %}
+max-lease-time {{ dhcpd_global_max_lease_time }};
 
+{% endif %}
+{% if dhcpd_log_facility|d() and dhcpd_log_facility %}
+log-facility {{ dhcpd_log_facility }};
+
+{% endif %}
+{% if dhcpd_auto_options|d() and dhcpd_auto_options %}
+{% include 'auto_options.j2' %}
 {% endif %}
 {% if dhcpd_options is defined and dhcpd_options %}
 # Configuration options