Add way to periodically trim Nova DB

We're adding 2 services that are responsible for executing db purge and
archive_deleted_rows. Services will be deployed by default, but left
stopped/disabled. This way we allow deployers to enable/disable
feature by changing value of nova_archive/purge_deleted.

Otherwise, when variables set to true once, setting them to false won't
lead to stopoing of DB trimming and that would need to be done manualy.

Change-Id: I9f110f663fae71f5f3c01c6d09e6d1302d517466

defaults/main.yml

@@ -785,3 +785,28 @@ nova_pki_install_certificates:
     group: "{{ nova_system_user_name }}"
     mode: "0600"
     condition: "{{ nova_backend_ssl }}"
+
+# Periodically move records for deleted resources to shadow tables
+nova_archive_deleted: False
+# When to start archive task. Reffer to Systemd Calendar Events for guidance
+# on format:
+# https://www.freedesktop.org/software/systemd/man/systemd.time.html#Calendar%20Events
+nova_archive_deleted_on_calendar: "*-*-* 00:00:00"
+# Archive events that are older then the timeframe below.
+# Should be in a format of bash date string
+nova_archive_deleted_before: "6 month ago"
+# Delete records instead of moving them to shadow tables
+nova_archive_deleted_purge: False
+# Archive instance task log
+nova_archive_task_log: False
+# Delay the timer by a randomly selected amount of time.
+nova_archive_deleted_randomized_delay_sec: 0
+
+# Periodically purge shadow tables, where archived records are stored
+nova_purge_deleted: False
+# When to start purge task.
+nova_purge_deleted_on_calendar: "*-*-* 01:00:00"
+# Purge events that are older then the timeframe below.
+nova_purge_deleted_before: "24 month ago"
+# Delay the timer by a randomly selected amount of time.
+nova_purge_deleted_randomized_delay_sec: 0

releasenotes/notes/nova_db_cleanup_services-a39bafaaacfb4671.yaml

@@ -0,0 +1,19 @@
+---
+features:
+  - |
+    Added option to periodically clean-up deleted records from Nova
+    database. Having a lot of records for the deleted instances affects
+    service performance.
+    With that 2 new services are being introduced: ``nova-archive-deleted``
+    and ``nova-purge-deleted`` that will be called periodically using
+    corresponsive systemd timers on the first nova-conductor host.
+
+    By default these services are disabled/stopped and database cleanup
+    is not performed. You can enable this behaviour by defining variables
+    ``nova_archive_deleted`` and ``nova_purge_deleted``.
+
+    Service ``nova-archive-deleted`` will execute
+    `nova-manage db archive_deleted_rows` while ``nova-archive-deleted``
+    will execute `nova-manage db purge`. Please correspond to nova-manage
+    documentation for more information on what these commands do:
+    https://docs.openstack.org/nova/latest/cli/nova-manage.html

tasks/nova_db_post_setup.yml

@@ -53,3 +53,49 @@
   when:
     - data_migrations is not skipped
     - data_migrations is succeeded
+
+- name: Create service and timer for archiving deleted records
+  include_role:
+    name: systemd_service
+  vars:
+    systemd_service_restart_changed: false
+    systemd_user_name: "{{ nova_system_user_name }}"
+    systemd_group_name: "{{ nova_system_group_name }}"
+    systemd_tempd_prefix: openstack
+    systemd_slice_name: "{{ nova_system_slice_name }}"
+    systemd_lock_dir: "{{ nova_lock_dir }}"
+    systemd_services:
+      - service_name: "nova-archive-deleted"
+        execstarts:
+          - /bin/sh -c "{{ _db_nova_bin }}/nova-manage db archive_deleted_rows --until-complete --all-cells --before \"$(date -d '{{ nova_archive_deleted_before }}' +'%%Y-%%m-%%d %%H:%%M')\" {{ (nova_archive_deleted_purge) | ternary('--purge', '') }} {{ (nova_archive_task_log) | ternary('--task-log', '') }}"
+        environment:
+          UMASK: '0640'
+          UMASK_DIR: '0750'
+        program_sandboxing:
+          RuntimeDirectory: 'nova-archive-deleted'
+        enabled: "{{ nova_archive_deleted }}"
+        timer:
+          state: "{{ nova_archive_deleted | ternary('started', 'stopped') }}"
+          enabled: "{{ nova_archive_deleted }}"
+          options:
+            OnCalendar: "{{ nova_archive_deleted_on_calendar }}"
+            RandomizedDelaySec: "{{ nova_archive_deleted_randomized_delay_sec }}"
+            Persistent: true
+            Unit: "nova-archive-deleted.service"
+      - service_name: "nova-purge-deleted"
+        execstarts:
+          - /bin/sh -c "{{ _db_nova_bin }}/nova-manage db purge --until-complete --all-cells --before \"$(date -d '{{ nova_purge_deleted_before }}' +'%%Y-%%m-%%d %%H:%%M')\""
+        environment:
+          UMASK: '0640'
+          UMASK_DIR: '0750'
+        program_sandboxing:
+          RuntimeDirectory: 'nova-purge-deleted'
+        enabled: "{{ nova_purge_deleted }}"
+        timer:
+          state: "{{ nova_purge_deleted | ternary('started', 'stopped') }}"
+          enabled: "{{ nova_purge_deleted }}"
+          options:
+            OnCalendar: "{{ nova_purge_deleted_on_calendar }}"
+            RandomizedDelaySec: "{{ nova_purge_deleted_randomized_delay_sec }}"
+            Persistent: true
+            Unit: "nova-purge-deleted.service"