Restart all nova services after upgrade

During an upgrade, nova pins the version of RPC calls to the minimum
seen across all services. This ensures that old services do not receive
data they cannot handle. After the upgrade is complete, all nova
services are supposed to be reloaded via SIGHUP to cause them to check
again the RPC versions of services and use the new latest version which
should now be supported by all running services.

Due to a bug [1] in oslo.service, sending services SIGHUP is currently
broken. We replaced the HUP with a restart for the nova_compute
container for bug 1821362, but not other nova services. It seems we need
to restart all nova services to allow the RPC version pin to be removed.

Testing in a Queens to Rocky upgrade, we find the following in the logs:

Automatically selected compute RPC version 5.0 from minimum service
version 30

However, the service version in Rocky is 35.

There is a second issue in that it takes some time for the upgraded
services to update the nova services database table with their new
version. We need to wait until all nova-compute services have done this
before the restart is performed, otherwise the RPC version cap will
remain in place. There is currently no interface in nova available for
checking these versions [2], so as a workaround we use a configurable
delay with a default duration of 30 seconds. Testing showed it takes
about 10 seconds for the version to be updated, so this gives us some
headroom.

This change restarts all nova services after an upgrade, after a 30
second delay.

[1] https://bugs.launchpad.net/oslo.service/+bug/1715374
[2] https://bugs.launchpad.net/nova/+bug/1833542

Change-Id: Ia6fc9011ee6f5461f40a1307b72709d769814a79
Closes-Bug: #1833069
Related-Bug: #1833542

ansible/roles/nova/defaults/main.yml

@@ -394,6 +394,15 @@ nova_services_require_nova_conf:
   - nova-scheduler
   - nova-spicehtml5proxy
 
+# After upgrading nova-compute, services will have an RPC version cap in place.
+# We need to restart all services that communicate with nova-compute in order
+# to allow them to use the latest RPC version. Ideally, there would be a way to
+# check whether all nova services are using the latest version, but currently
+# there is not. Instead, wait a short time for all nova compute services to
+# update the version of their service in the database.  This seems to take
+# around 10 seconds, but the default is 30 to allow room for slowness.
+nova_compute_startup_delay: 30
+
 ####################
 # Notification
 ####################

ansible/roles/nova/handlers/main.yml

@@ -319,3 +319,55 @@
     - kolla_action != "config"
     - inventory_hostname in groups['compute']
     - enable_nova_fake | bool
+
+# NOTE(mgoddard): After upgrading nova-compute, services will have an RPC
+# version cap in place.  We need to restart all services that communicate with
+# nova-compute in order to allow them to use the latest RPC version. Ideally,
+# there would be a way to check whether all nova services are using the latest
+# version, but currently there is not. Instead, wait a short time for all nova
+# compute services to update the version of their service in the database.
+# This seems to take around 10 seconds, but the default is 30 to allow room
+# for slowness.
+
+- name: Wait for nova-compute services to update service versions
+  pause:
+    seconds: "{{ nova_compute_startup_delay }}"
+  run_once: true
+  when:
+    - kolla_action == 'upgrade'
+  listen:
+    - Restart nova-compute container
+    - Restart nova-compute-ironic container
+    - Restart nova-compute-fake containers
+
+# NOTE(mgoddard): Currently (just prior to Stein release), sending SIGHUP to
+# nova compute services leaves them in a broken state in which they cannot
+# start new instances. The following error is seen in the logs:
+# "In shutdown, no new events can be scheduled"
+# To work around this we restart the nova-compute services.
+# Speaking to the nova team, this seems to be an issue in oslo.service,
+# with a fix proposed here: https://review.openstack.org/#/c/641907.
+# This issue also seems to affect the proxy services, which exit non-zero in
+# reponse to a SIGHUP, so restart those too.
+# The issue actually affects all nova services, since they remain with RPC
+# version pinned to the previous release:
+# https://bugs.launchpad.net/kolla-ansible/+bug/1833069.
+# TODO(mgoddard): Use SIGHUP when this bug has been fixed.
+
+- name: Restart nova services to remove RPC version cap
+  become: true
+  kolla_docker:
+    action: restart_container
+    common_options: "{{ docker_common_options }}"
+    name: "{{ item.value.container_name }}"
+  when:
+    - kolla_action == 'upgrade'
+    - inventory_hostname in groups[item.value.group]
+    - item.value.enabled | bool
+    - item.key in nova_services_require_nova_conf
+    - item.key != 'placement-api'
+  with_dict: "{{ nova_services }}"
+  listen:
+    - Restart nova-compute container
+    - Restart nova-compute-ironic container
+    - Restart nova-compute-fake containers

ansible/roles/nova/tasks/legacy_upgrade.yml

@@ -26,5 +26,3 @@
 
 - name: Flush handlers
   meta: flush_handlers
-
-- include_tasks: reload.yml

ansible/roles/nova/tasks/reload.yml

@@ -1,38 +0,0 @@
----
-# This play calls sighup on every service to refresh upgrade levels
-
-# NOTE(mgoddard): Currently (just prior to Stein release), sending SIGHUP to
-# nova compute services leaves them in a broken state in which they cannot
-# start new instances. The following error is seen in the logs:
-# "In shutdown, no new events can be scheduled"
-# To work around this we restart the nova-compute services.
-# Speaking to the nova team, this seems to be an issue in oslo.service,
-# with a fix proposed here: https://review.opendev.org/#/c/641907.
-# This issue also seems to affect the proxy services, which exit non-zero in
-# reponse to a SIGHUP, so restart those too.
-# TODO(mgoddard): Remove this workaround when this bug has been fixed.
-
-- name: Send SIGHUP to nova services
-  become: true
-  command: docker exec -t {{ item.value.container_name }} kill -1 1
-  when:
-    - inventory_hostname in groups[item.value.group]
-    - item.value.enabled | bool
-    - item.key in nova_services_require_nova_conf
-    - not item.key.startswith('nova-compute')
-    - not item.key.endswith('proxy')
-  with_dict: "{{ nova_services }}"
-
-- name: Restart nova compute and proxy services
-  become: true
-  kolla_docker:
-    action: restart_container
-    common_options: "{{ docker_common_options }}"
-    name: "{{ item.value.container_name }}"
-  when:
-    - inventory_hostname in groups[item.value.group]
-    - item.value.enabled | bool
-    - item.key in nova_services_require_nova_conf
-    - item.key.startswith('nova-compute')
-      or item.key.endswith('proxy')
-  with_dict: "{{ nova_services }}"

ansible/roles/nova/tasks/rolling_upgrade.yml

@@ -25,8 +25,6 @@
 - name: Flush handlers
   meta: flush_handlers
 
-- include_tasks: reload.yml
-
 - name: Migrate Nova database
   vars:
     nova_api: "{{ nova_services['nova-api'] }}"