Add support for clustered servers

Certain services are expected to be served by more than one server,
think of git mirrors, zuul workers etc.
While we could define all of them with numbered pattern manually
in the resources.yaml file, this gets unwieldy and boring
if the count is large, repeating on and on the same
server stanzas with just <service_name><$NODE_COUNT>.
This change allows to put a 'node_count' attribute to the server
resource. With it, the role will create as many servers as
'node_count' by numbering the servers as <server_name><$NODE_COUNT>.
e.g.

servers:
  - name: logstash-worker.openstack.org
    image: ubuntu-trusty
    flavor: d1
    node_count: 2

That would make the role to create two server instances named
'logstash-worker01.openstack.org' and 'logstash-worker02.openstack.org'

Change-Id: I220a2786efe56187f60f1eed2f32e661e6d3ed3f

tasks/create_server.yml

@@ -5,7 +5,7 @@
 - os_server:
     cloud: "{{ item_cloud.oscc_cloud|default(item_cloud.name) }}"
     state: "{{ item_server.state|default(omit) }}"
-    name: "{{ item_server.name }}"
+    name: "{{ item_server.name.partition('.')[0] }}{{ '' if item_server.node_count is not defined else item }}{{ item_server.name.partition('.')[1] + item_server.name.partition('.')[2] }}"
     image: "{{ item_server.image }}"
     auto_ip: "{{ item_server.auto_ip|default(omit) }}"
     boot_from_volume: "{{ item_server.boot_from_volume|default(omit) }}"
@@ -28,6 +28,7 @@
     userdata: "{{ item_server.userdata|default(omit) }}"
     volume_size: "{{ item_server.volume_size|default(omit) }}"
     volumes: "{{ item_server.volumes|default(omit) }}"
+  with_sequence: start=1 end={{ item_server.node_count|default(1) }} format=%02x
   register: os_server_result
 
 - add_host: name={{ item.server.name }} groups=cl_servers_just_created ansible_ssh_host={{ item.server.public_v4 }}

tests/resources.yml

@@ -29,6 +29,16 @@ clouds:
         image: cirros-0.3.4-x86_64-uec
         flavor: c1
         network: test_network
+      - name: test_cluster
+        image: cirros-0.3.4-x86_64-uec
+        flavor: c1
+        network: test_network
+        node_count: 2
+      - name: test_cluster.testdomain
+        image: cirros-0.3.4-x86_64-uec
+        flavor: c1
+        network: test_network
+        node_count: 2
     networks:
       - name: test_network
     subnets:

tests/test.yaml

@@ -68,3 +68,35 @@
 
     - name: Assert test-network network has been created
       assert: { that: result.rc == 0 }
+
+    - name: Querying for test_cluster01 server
+      command: openstack --os-cloud devstack server show test_cluster01
+      register: result
+      changed_when: False
+
+    - name: Assert test_cluster01 server has been created
+      assert: { that: result.rc == 0 }
+
+    - name: Querying for test_cluster02 server
+      command: openstack --os-cloud devstack server show test_cluster02
+      register: result
+      changed_when: False
+
+    - name: Assert test_cluster02 server has been created
+      assert: { that: result.rc == 0 }
+
+    - name: Querying for test_cluster01.testdomain server
+      command: openstack --os-cloud devstack server show test_cluster01.testdomain
+      register: result
+      changed_when: False
+
+    - name: Assert test_cluster01.testdomain server has been created
+      assert: { that: result.rc == 0 }
+
+    - name: Querying for test_cluster02.testdomain server
+      command: openstack --os-cloud devstack server show test_cluster02.testdomain
+      register: result
+      changed_when: False
+
+    - name: Assert test_cluster02.testdomain server has been created
+      assert: { that: result.rc == 0 }