roles/hass-dhcp: Deploy DHCP server for HA

The *hass-dhcp* role installs dnsmasq and configures it to serve DHCP
requests on the Home Assistant network. Since this network is not
routed, the regular DHCP relay/server setup will not work.

roles/hass-dhcp/defaults/main.yml

@@ -0,0 +1,5 @@
+hass_dhcp_range:
+  start: 192.168.1.100
+  end: 192.168.1.250
+hass_dhcp_lease_time: 1h
+hass_dns_domain: homeassistant.io

roles/hass-dhcp/handlers/main.yml

@@ -0,0 +1,4 @@
+- name: restart dnsmasq
+  service:
+    name: dnsmasq
+    state: restarted

roles/hass-dhcp/tasks/main.yml

@@ -0,0 +1,14 @@
+- name: ensure dnsmasq is installed
+  package:
+    name: dnsmasq
+    state: present
+  tags:
+  - install
+
+- name: ensure dnsmasq is configured for homeassistant
+  template:
+    src: homeassistant.dnsmasq.conf.j2
+    dest: /etc/dnsmasq.d/homeassistant.conf
+    mode: '0644'
+  notify:
+  - restart dnsmasq

roles/hass-dhcp/templates/homeassistant.dnsmasq.conf.j2

@@ -0,0 +1,3 @@
+interface={{ hass_interface }}
+dhcp-range={{ hass_dhcp_range.start }},{{ hass_dhcp_range.end }},{{ hass_dhcp_lease_time }}
+domain={{ hass_dns_domain }}