Fix ctlplane-ip-range validations

The `undercloud.conf` file has now 2 sections (DEFAULT and ctlplane-subnet).
A small numbers of parameters have been deprecated and moved to the
ctlplane-subnet section. Morever, the `undercloud_conf` custom plugin has some
issues to generate facts coming from the 'undercloud.conf' file due to the new
section.

This patch proposes to use the 'ini' custom plugin to get parameter's values
from the undercloud.conf file instead of using the 'undercloud_conf' custom
plugin.

Resolves: rhbz#1660075

Change-Id: I7689e1c8f7f44058b0ad44318c5eef522ddfad52
Signed-off-by: Gael Chamoulaud <gchamoul@redhat.com>

validations/ctlplane-ip-range.yaml

@@ -2,7 +2,7 @@
 - hosts: undercloud
   vars:
     metadata:
-      name: Check the number of IP addresses available to overcloud nodes
+      name: Check the number of IP addresses available for the overcloud nodes
       description: >
         Verify that the number of IP addresses defined in `dhcp_start` and
         `dhcp_end` fields in `undercloud.conf` is not too low.
@@ -13,13 +13,27 @@
   - name: Get the path of tripleo undercloud config file
     become: true
     hiera: name="tripleo_undercloud_conf_file"
-  - name: Gather undercloud.conf values
+
+  - name: Get dhcp_start value from the undercloud.conf file
     become: true
-    undercloud_conf:
-      undercloud_conf_path={{ tripleo_undercloud_conf_file }}
-      ignore_missing=true
+    ini:
+      path: "{{ tripleo_undercloud_conf_file }}"
+      section: ctlplane-subnet
+      key: dhcp_start
+      ignore_missing_file: True
+    register: dhcp_start
+
+  - name: Get dhcp_end value from the undercloud.conf file
+    become: true
+    ini:
+      path: "{{ tripleo_undercloud_conf_file }}"
+      section: ctlplane-subnet
+      key: dhcp_end
+      ignore_missing_file: True
+    register: dhcp_end
+
   - name: Check the size of the DHCP range for overcloud nodes
     ip_range:
-      start: "{{ undercloud_conf.DEFAULT.dhcp_start|default('192.0.2.5') }}"
-      end: "{{ undercloud_conf.DEFAULT.dhcp_end|default('192.0.2.24') }}"
+      start: "{{ dhcp_start.value|default('192.0.2.5') }}"
+      end: "{{ dhcp_end.value|default('192.0.2.24') }}"
       min_size: "{{ ctlplane_iprange_min_size }}"