[Queens] Add workflow to do cellv2 host discovery

When the compute bootstrap node gets blacklisted or deployment is
run with skip-deploy-identifier the discovery job in step_5
won't run and requires a manual post deploy/scale step.

This introduce a workflow to run the discovery via an ansible
playbook.

Change-Id: I54d42df162a6744806301d97bca5d94e5f380a2b
Related-Bug: #1831711

playbooks/nova_cellv2_host_discover.yaml

@@ -0,0 +1,21 @@
+---
+- hosts: nova_discovery_nodes
+  gather_facts: True
+  vars:
+    container_name: "{{ nova_host_discovery_container }}"
+  tasks:
+    - block:
+      - name: Check if discovery container exist
+        shell: docker ps | grep {{ container_name }}$
+        register: is_discovery_container_running
+        ignore_errors: True
+      - name: Set fact discover_hosts
+        set_fact:
+          discover_hosts: "{{ is_discovery_container_running.rc == 0 }}"
+    - name: Discovering nova hosts
+      command: docker exec {{ container_name }} nova-manage cell_v2 discover_hosts --by-service
+      become: true
+      changed_when: false
+      delegate_to: '{{ groups[''nova_discovery_nodes''][0] }}'
+      when:
+        - discover_hosts|bool

workbooks/nova_host_discovery.yaml

@@ -0,0 +1,53 @@
+---
+version: '2.0'
+name: tripleo.nova.v1
+description: TripleO nova workflows
+
+workflows:
+
+  cellv2_discovery:
+    description: cellv2 host discovery
+    input:
+      - nova_host_discovery_ansible_playbook
+      - nova_host_discovery_container
+      - nova_host_discovery_service
+      - ansible_extra_env_variables:
+          ANSIBLE_HOST_KEY_CHECKING: 'False'
+          ANSIBLE_SSH_RETRIES: '3'
+    tags:
+      - tripleo-common-managed
+    tasks:
+      get_overcloud_stack_details:
+        publish:
+          nova_discovery_ips: <% env().get('service_ips', {}).get($.nova_host_discovery_service + '_ctlplane_node_ips', []) %>
+        on-success: enable_ssh_admin
+
+      enable_ssh_admin:
+        workflow: tripleo.access.v1.enable_ssh_admin
+        input:
+          ssh_servers: <% $.nova_discovery_ips %>
+        on-success: get_private_key
+
+      get_private_key:
+        action: tripleo.validations.get_privkey
+        publish:
+          private_key: <% task().result %>
+        on-success: discover_hosts
+
+      discover_hosts:
+        action: tripleo.ansible-playbook
+        input:
+          inventory:
+            nova_discovery_nodes:
+              hosts: <% $.nova_discovery_ips.toDict($, {}) %>
+          verbosity: 0
+          playbook: <% $.nova_host_discovery_ansible_playbook %>
+          remote_user: tripleo-admin
+          become: true
+          become_user: root
+          ssh_private_key: <% $.private_key %>
+          ssh_common_args: '-o StrictHostKeyChecking=no'
+          ssh_extra_args: '-o UserKnownHostsFile=/dev/null'
+          extra_env_variables: <% $.ansible_extra_env_variables %>
+          extra_vars:
+            nova_host_discovery_container: <% $.nova_host_discovery_container %>