Persist DNS configuration for nodes for openstack provider

* Firstly, provision a Heat stack with given public resolvers.
* After the DNS node configured as an authoritative server,
  switch the Heat stack's Neutron subnet to that resolver
  (private_dns_server) the way it to become the first entry pushed
  into the  hosts /etc/resolv.conf. It will be serving the cluster
  domain requests for OpenShift nodes and workloads.
* Drop post-provision /etc/reslov.conf nameserver hacks as not
  needed anymore.
* Fix dns floating IPs output and add the priv IPs output as well.
* Update docs, clarify localhost vs servers requirements, add
  required Network Manager setup step.
* Use post-provision task names instead of comments.

Signed-off-by: Bogdan Dobrelya <bdobreli@redhat.com>

3 files changed, 22 insertions, 14 deletions

diff --git a/roles/openstack-stack/tasks/main.yml b/roles/openstack-stack/tasks/main.yml
index 71c7bbe0d..a53e6350b 100644
--- a/roles/openstack-stack/tasks/main.yml
+++ b/roles/openstack-stack/tasks/main.yml
@@ -35,6 +35,11 @@
     template: "{{ stack_template_path }}"
     wait: yes
 
+# NOTE(bogdando) OS::Neutron::Subnet doesn't support live updates for
+# dns_nameservers, so we can't do that for the "create stack" task.
+- include: subnet_update_dns_servers.yaml
+  when: private_dns_server is defined
+
 - name: cleanup temp files
   file:
     path: "{{ stack_template_pre.path }}"
diff --git a/roles/openstack-stack/tasks/subnet_update_dns_servers.yaml b/roles/openstack-stack/tasks/subnet_update_dns_servers.yaml
new file mode 100644
index 000000000..be4f07b97
--- /dev/null
+++ b/roles/openstack-stack/tasks/subnet_update_dns_servers.yaml
@@ -0,0 +1,8 @@
+---
+- name: Live update the subnet's DNS servers
+  os_subnet:
+    name: openshift-ansible-{{ stack_name }}-subnet
+    network_name: openshift-ansible-{{ stack_name }}-net
+    state: present
+    use_default_subnetpool: yes
+    dns_nameservers: "{{ [private_dns_server|default(public_dns_nameservers[0])]|union(public_dns_nameservers)|unique }}"
diff --git a/roles/openstack-stack/templates/heat_stack.yaml.j2 b/roles/openstack-stack/templates/heat_stack.yaml.j2
index 00a46896c..8bf76b57c 100644
--- a/roles/openstack-stack/templates/heat_stack.yaml.j2
+++ b/roles/openstack-stack/templates/heat_stack.yaml.j2
@@ -61,18 +61,13 @@ outputs:
         - dns
         - name
 
-  dns_floating_ip:
-    description: Floating IP of the DNS
-    value:
-      get_attr:
-        - dns
-        - addresses
-        - str_replace:
-            template: openshift-ansible-cluster_id-net
-            params:
-              cluster_id: {{ stack_name }}
-        - 1
-        - addr
+  dns_floating_ips:
+    description: Floating IPs of the DNS
+    value: { get_attr: [ dns, floating_ip ] }
+
+  dns_private_ips:
+    description: Private IPs of the DNS
+    value: { get_attr: [ dns, private_ip ] }
 
 resources:
 
@@ -111,9 +106,9 @@ resources:
               params:
                 subnet_24_prefix: {{ subnet_prefix }}
       dns_nameservers:
-      {% for nameserver in dns_nameservers %}
+{% for nameserver in dns_nameservers %}
         - {{ nameserver }}
-      {% endfor %}
+{% endfor %}
 
   router:
     type: OS::Neutron::Router