Allow operators to use "ceilometer-upgrade" parameters

Allow operators to use custom parameters with the ceilometer-upgrade
command. This is quite useful when using the dynamic pollster subsystem;
that sub-system provides flexibility to create and edit pollsters configs,
which affects gnocchi resource-type configurations. However, Ceilometer
uses default and hard-coded resource-type configurations; if one customizes
some of its default resource-types, he/she can get into trouble during
upgrades. Therefore, the only way to work around it is to use the
"--skip-gnocchi-resource-types" flag. This PR introduces a method for
operators to execute such customization, and many others if needed.

Depends-On: https://review.opendev.org/#/c/718190/
Change-Id: I92f0edba92c9e3707d89b3ff4033ac886b29cf6d

ansible/roles/ceilometer/defaults/main.yml

@@ -121,3 +121,11 @@ ceilometer_ks_users:
     user: "{{ ceilometer_keystone_user }}"
     password: "{{ ceilometer_keystone_password }}"
     role: "admin"
+
+####################
+# Backend
+####################
+
+ceilometer_database_type: "gnocchi"
+
+ceilometer_upgrade_params: ""

ansible/roles/ceilometer/tasks/bootstrap_service.yml

@@ -10,7 +10,8 @@
     environment:
       KOLLA_BOOTSTRAP:
       KOLLA_CONFIG_STRATEGY: "{{ config_strategy }}"
-      CEILOMETER_DATABASE_TYPE: "gnocchi"
+      CEILOMETER_DATABASE_TYPE: "{{ ceilometer_database_type }}"
+      CEILOMETER_UPGRADE_PARAMS: "{{ ceilometer_upgrade_params }}"
     image: "{{ ceilometer_notification.image }}"
     labels:
       BOOTSTRAP:

releasenotes/notes/allow-custom-ceilometer-upgrade-params-c07eec4c1ef5a3d3.yaml

+---
+features:
+  - |
+    Allow operators to use custom parameters with the ceilometer-upgrade
+    command. This is quite useful when using the dynamic pollster subsystem;
+    that sub-system provides flexibility to create and edit pollsters configs,
+    which affects gnocchi resource-type configurations. However, Ceilometer
+    uses default and hard-coded resource-type configurations; if one customizes
+    some of its default resource-types, he/she can get into trouble during
+    upgrades. Therefore, the only way to work around it is to use the
+    "--skip-gnocchi-resource-types" flag. This release introduces a method for
+    operators to execute such customization, and many others if needed.