Add observability_data_only condition to node-exporter component

There are use cases where we'd like to take advantage of the unified
monitoring model in openstack, and the ceph cluster should provide a
set of deployed node exporters, but leave the data collection job to
a different component.
This patch introduces a new condition to allow a partial deployment
of the ceph monitoring stack: only node-exporter(s) are deployed
everywhere, but prometheus/grafana/alertmanager are skipped.

Change-Id: Ia1723394dae5ed03e50f2a236eb808f234e63331

tripleo_ansible/roles/tripleo_cephadm/defaults/main.yml

@@ -35,6 +35,7 @@ tripleo_cephadm_mode: "0755"
 tripleo_cephadm_keyring_permissions: "0644"
 tripleo_ceph_client_config_home: "/etc/ceph"
 tripleo_cephadm_dashboard_enabled: false
+tripleo_cephadm_observability_data_only: false
 tripleo_cephadm_wait_for_mons: true
 tripleo_cephadm_wait_for_mons_retries: 10
 tripleo_cephadm_wait_for_mons_delay: 20

tripleo_ansible/roles/tripleo_cephadm/tasks/monitoring.yaml

@@ -14,6 +14,23 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+- name: Apply node-exporter(s)
+  become: true
+  ceph_mkspec:
+    service_type: "node-exporter"
+    service_id: "node-exporter"
+    service_name: "node-exporter"
+    cluster: "{{ tripleo_cephadm_cluster }}"
+    apply: true
+    host_pattern: "*"
+    render_path: "{{ tripleo_cephadm_spec_home }}"
+    networks: "{{ tripleo_cephadm_monitoring_address_block }}"
+  environment:
+    CEPH_CONTAINER_IMAGE: "{{ tripleo_cephadm_container_ns + '/' + tripleo_cephadm_container_image + ':' + tripleo_cephadm_container_tag }}"
+    CEPH_CONTAINER_BINARY: "{{ tripleo_cephadm_container_cli }}"
+  when: tripleo_cephadm_dashboard_enabled | default(false) | bool or
+        tripleo_cephadm_observability_data_only | default(false) | bool
+
 - name: Build and apply the monitoring stack daemons
   block:
     # Using two tasks with a boolean due to the ansible bug: https://github.com/ansible/ansible/issues/68364
@@ -29,21 +46,6 @@
       with_items: "{{ groups['ceph_mgr'] }}"
       when: not tripleo_cephadm_fqdn | bool
 
-    - name: Apply node-exporter(s)
-      become: true
-      ceph_mkspec:
-        service_type: "node-exporter"
-        service_id: "node-exporter"
-        service_name: "node-exporter"
-        cluster: "{{ tripleo_cephadm_cluster }}"
-        apply: true
-        host_pattern: "*"
-        render_path: "{{ tripleo_cephadm_spec_home }}"
-        networks: "{{ tripleo_cephadm_monitoring_address_block }}"
-      environment:
-        CEPH_CONTAINER_IMAGE: "{{ tripleo_cephadm_container_ns + '/' + tripleo_cephadm_container_image + ':' + tripleo_cephadm_container_tag }}"
-        CEPH_CONTAINER_BINARY: "{{ tripleo_cephadm_container_cli }}"
-
     - name: Config ssl cert(s) and key(s) for the exposed components
       become: true
       block:
@@ -82,7 +84,9 @@
         - {"daemon": "grafana", "port": "{{ tripleo_cephadm_grafana_port | default(3100) }}"}
         - {"daemon": "prometheus", "port": "{{ tripleo_cephadm_prometheus_port | default(9092) }}"}
         - {"daemon": "alertmanager", "port": "{{ tripleo_cephadm_alertmanager_port | default(9093) }}"}
-  when: tripleo_cephadm_dashboard_enabled | bool
+  when:
+    - tripleo_cephadm_dashboard_enabled | default(false) | bool
+    - not tripleo_cephadm_observability_data_only | default(false) | bool
 
 - include_tasks: dashboard/dashboard.yaml
   when: tripleo_cephadm_dashboard_enabled | bool