feat: add multiple options and ranges to dnsmasq

Added the ability to manage multiple ranges and options in dnsmasq by
defining multiple environment variables. Set the dhcp-authoritative flag
by default.

components/ironic/dnsmasq-cm.yaml

@@ -3,10 +3,12 @@ kind: ConfigMap
 metadata:
   name: ironic-dnsmasq
 data:
+  # common separated list of DHCP tagged configs
+  DHCP_TAGS: tag1
   # When defining the IP address range, make sure to include subnet
   # information, especially for the pools serving relayed requests
-  DHCP_RANGE: 192.168.200.4,192.168.200.12,255.255.255.0,192.168.200.255,30m
-  DHCP_RANGE_ROUTER: 192.168.200.1
+  DHCP_RANGE_TAG1: 192.168.200.4,192.168.200.12,255.255.255.0,192.168.200.255,30m
+  DHCP_OPTION_TAG1_ROUTER: 192.168.200.1
   # external IP address of Ingress. Used to populate DNS A records for the
   # Understack components
   INGRESS_IP: 192.168.1.177

containers/dnsmasq/dnsmasq.conf.j2

@@ -27,12 +27,51 @@ log-queries=extra
 # don't advertise /etc/hosts entries
 no-hosts
 
-# DHCP range to hand out
-{% if env.DHCP_RANGE is defined %}
-dhcp-range={{ env.DHCP_RANGE }}
-shared-network=eth0,{{ env.DHCP_RANGE_ROUTER }}
-dhcp-option=option:router,{{ env.DHCP_RANGE_ROUTER }}
-{% endif %}
+# common DHCP config
+# the environment variables will be named like:
+# DHCP_RELAY_MAC_$NAME
+# DHCP_RANGE_$NAME
+# DHCP_OPTION_$NAME_$OPTION
+{% macro dhcp_config(name) -%}
+{% set dhcp_circuitid = "DHCP_SETTAG_" ~ name|upper ~ "_CIRCUITID" -%}
+{% set dhcp_range = "DHCP_RANGE_" ~ name|upper -%}
+{% set dhcp_proxy = "DHCP_PROXY_" ~ name|upper -%}
+{% set dhcp_option = "DHCP_OPTION_" ~ name|upper ~ "_" -%}
+{% if env[dhcp_circuitid] is defined %}
+# tag the traffic with the PXE relay MAC
+{% set tag = name|lower ~ "," -%}
+dhcp-circuitid=set:{{ tag }}{{ env[dhcp_circuitid] }}
+{% else -%}
+# no tag by the PXE relay MAC
+{% set tag = "" -%}
+{%- endif %}
+dhcp-range={{ tag }}{{ env[dhcp_range] }}
+shared-network=eth0,{{ env[dhcp_range].split(',')[0] }}
+{% if env[dhcp_proxy] is defined -%}
+shared-network=eth0,{{ env[dhcp_proxy }}
+{{ dhcp_proxy_list.append(env[dhcp_proxy]) }}
+{%- endif %}
+{% for key, value in env.items() if key.startswith(dhcp_option) -%}
+{% set option = key|replace(dhcp_option, '') -%}
+{% if option|int(-1) != -1 -%}
+{% set option_prefix = '' -%}
+{% else -%}
+{% set option_prefix = 'option:' -%}
+{% endif -%}
+dhcp-option={{ tag }}{{ option_prefix }}{{ option|replace('_', '-')|lower }},{{ value }}
+{%- endfor %}
+{%- endmacro %}
+
+dhcp-authoritative
+# DHCP ranges to hand out
+{% set dhcp_proxy_list = [] -%}
+{{ dhcp_proxy_list.append(env.POD_IP) }}
+{% set dhcp_tags_str = env.DHCP_TAGS|default('default') -%}
+{% set dhcp_tags = dhcp_tags_str.split(',') -%}
+{% for name in dhcp_tags %}
+{{ dhcp_config(name) }}
+{% endfor %}
+dhcp-proxy={{ dhcp_proxy_list|join(',') }}
 
 # don't set to enable logging
 {% if env.LOG_DHCP_QUERIES | default(False, True) %}
@@ -68,3 +107,4 @@ address=/{{ component }}.{{ env.DNS_ZONE }}/{{ env.INGRESS_IP }}
 {% endfor %}
 
 dhcp-option=option:dns-server,{{ env.get('DNS_IP', env['INGRESS_IP']) }}
+# end of template

docs/networking.md

@@ -45,4 +45,13 @@ spec:
 You will want to review and edit the dnsmasq DHCP configuration for your environment:
 <https://github.com/rackerlabs/understack/blob/main/components/ironic/dnsmasq-cm.yaml>
 
-The important settings to review are `DHCP_RANGE`, `DHCP_RANGE_ROUTER`, and `INGRESS_IP`.
+The dnsmasq setup can listen for multiple ranges by configuring a list in
+the `DHCP_TAGS` value. So if you have `DHCP_TAGS: tag1,tag2` it would
+expect the following variables:
+
+* `DHCP_RANGE_TAG1` and `DHCP_RANGE_TAG2` to define the DHCP range to serve up
+* optionally `DHCP_OPTION_TAG1_ROUTER` to define a default router for the tag1 range
+* optionally `DHCP_PROXY_TAG1` to define the DHCP relay agent's gateway IP
+
+To identify the ranges you must set `DHCP_SETTAG_TAG1_CIRCUITID` and `DHCP_SETTAG_TAG2_CIRCUITID`
+to the values provided. If you only use 1 tag, you do not need to set these.