prevent validations from failing when undercloud.conf is missing:

- check-network-gateway, ctlplane-iprange and dhcp-provisioning now don't fail when
  undercloud.conf is missing, they use default values for the validation instead
- module undercloud_conf.py has a new option ignore_missing which (if set to true)
  prevents the module from failing when undercloud.conf does not exist

Change-Id: I859f814f1bbeda267d7f39d27edce87a41126138
Closes-Bug: #1643810

validations/check-network-gateway.yaml

@@ -14,7 +14,9 @@
     hiera: name="tripleo_undercloud_conf_file"
   - name: Gather undercloud.conf values
     become: true
-    undercloud_conf: undercloud_conf_path={{ tripleo_undercloud_conf_file }}
+    undercloud_conf:
+      undercloud_conf_path={{ tripleo_undercloud_conf_file }}
+      ignore_missing=true
   - name: "Test network_gateway if different from local_ip"
     icmp_ping: host={{ undercloud_conf.DEFAULT.network_gateway }}
     when: >

validations/ctlplane-ip-range.yaml

@@ -15,7 +15,9 @@
     hiera: name="tripleo_undercloud_conf_file"
   - name: Gather undercloud.conf values
     become: true
-    undercloud_conf: undercloud_conf_path={{ tripleo_undercloud_conf_file }}
+    undercloud_conf:
+      undercloud_conf_path={{ tripleo_undercloud_conf_file }}
+      ignore_missing=true
   - name: Check the size of the DHCP range for overcloud nodes
     ip_range:
       start: "{{ undercloud_conf.DEFAULT.dhcp_start|default('192.0.2.5') }}"

validations/dhcp-provisioning.yaml

@@ -17,7 +17,9 @@
   - name: Get the path of tripleo undercloud config file
     hiera: name="tripleo_undercloud_conf_file"
   - name: Gather undercloud.conf values
-    undercloud_conf: undercloud_conf_path={{ tripleo_undercloud_conf_file }}
+    undercloud_conf:
+      undercloud_conf_path={{ tripleo_undercloud_conf_file }}
+      ignore_missing=true
   - name: Install python-virtualenv
     package: name=python-virtualenv state=present
   - name: Install scapy

validations/library/undercloud_conf.py

@@ -23,6 +23,7 @@ from ansible.module_utils.basic import *  # noqa
 def main():
     module = AnsibleModule(argument_spec=dict(
         undercloud_conf_path=dict(required=True, type='str'),
+        ignore_missing=dict(type='bool'),
     ))
 
     undercloud_conf_path = module.params.get('undercloud_conf_path')
@@ -37,6 +38,9 @@ def main():
 
         module.exit_json(changed=False,
                          ansible_facts={u'undercloud_conf': result})
+    elif module.params.get('ignore_missing'):
+        module.exit_json(changed=False,
+                         ansible_facts={u'undercloud_conf': {'DEFAULT': {}}})
     else:
         module.fail_json(msg="Could not open the undercloud.conf file at '%s'"
                          % undercloud_conf_path)