[neutron] Configure Metadata Service Query Rate-limiting

This change introduces a value to our neutron deployment allowing to
turn on and configure the rate-limiting for the metadata service running
as part of our neutron network agents. It's turned off by default but
can be toggled on by providing the respective values during a helm
release.

For more information about it's capabilities and configuration, refer to
https://docs.openstack.org/neutron/latest/admin/config-metadata-rate-limiting.html

Author: felix-kaestner

openstack/neutron/templates/etc/_neutron.conf.tpl

@@ -157,6 +157,13 @@ quota_security_group_rule = 4
 # Minimum value: 1
 thread_pool_size = 3
 
+[metadata_rate_limiting]
+rate_limit_enabled = {{ .Values.metadata.rate_limit.enabled }}
+base_window_duration: {{ .Values.metadata.rate_limit.base_window_duration }}
+base_query_rate_limit: {{ .Values.metadata.rate_limit.base_query_rate_limit }}
+burst_window_duration: {{ .Values.metadata.rate_limit.burst_window_duration }}
+burst_query_rate_limit: {{ .Values.metadata.rate_limit.burst_query_rate_limit }}
+
 {{- include "ini_sections.cache" . }}
 
 {{- if hasPrefix "caracal" .Values.imageVersion }}

openstack/neutron/values.yaml

@@ -985,6 +985,14 @@ api-ratelimit-redis:
   alerts:
     support_group: network-api
 
+metadata:
+  rate_limit:
+    enabled: false
+    base_window_duration: 10
+    base_query_rate_limit: 10
+    burst_window_duration: 10
+    burst_query_rate_limit: 10
+
 utils:
   trust_bundle:
     enable: false