[ironic] add coordination backend for ironic inspector

Change-Id: Ide82b7a7fa6752b60f2c9c31cdc4c79183fc62f6

ansible/group_vars/all.yml

@@ -1170,6 +1170,9 @@ grafana_public_endpoint: "{{ public_protocol }}://{{ kolla_external_fqdn | put_a
 ironic_internal_endpoint: "{{ internal_protocol }}://{{ ironic_internal_fqdn | put_address_in_context('url') }}:{{ ironic_api_port }}"
 ironic_public_endpoint: "{{ public_protocol }}://{{ ironic_external_fqdn | put_address_in_context('url') }}:{{ ironic_api_port }}"
 
+# Valid options are [ '', redis, etcd ]
+ironic_coordination_backend: "{{ 'redis' if enable_redis|bool else 'etcd' if enable_etcd|bool else '' }}"
+
 ########
 # Swift
 ########

ansible/roles/ironic/templates/ironic-inspector.conf.j2

@@ -73,3 +73,14 @@ driver = {{ ironic_inspector_pxe_filter }}
 [iptables]
 dnsmasq_interface = {{ ironic_dnsmasq_interface }}
 {% endif %}
+
+[coordination]
+{% if ironic_coordination_backend == 'redis' %}
+backend_url = {{ redis_connection_string }}
+{% elif ironic_coordination_backend == 'etcd' %}
+# NOTE(yoctozepto): etcd-compatible tooz drivers do not support multiple endpoints here (verified in Stein, Train)
+# NOTE(yoctozepto): we must use etcd3gw (aka etcd3+http) due to issues with alternative (etcd3) and eventlet (as used by cinder)
+# see https://bugs.launchpad.net/kolla-ansible/+bug/1854932
+# and https://review.opendev.org/466098 for details
+backend_url = etcd3+{{ etcd_protocol }}://{{ 'api' | kolla_address(groups['etcd'][0]) | put_address_in_context('url') }}:{{ etcd_client_port }}
+{% endif %}

etc/kolla/globals.yml

@@ -611,6 +611,9 @@
 # List of extra kernel parameters passed to the kernel used during inspection
 #ironic_inspector_kernel_cmdline_extras: []
 
+# Valid options are [ '', redis, etcd ]
+#ironic_coordination_backend: "{{ 'redis' if enable_redis|bool else 'etcd' if enable_etcd|bool else '' }}"
+
 ######################################
 # Manila - Shared File Systems Options
 ######################################

releasenotes/notes/ironic-inspector-coordination-19d47c1d2849d56f.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Adds support for configuring a coordination backend for Ironic
+    Inspector via the ``ironic_coordination_backend`` variable.
+    Possible values are ``redis`` or ``etcd``.