Decoupling number of API and RPC workers for neutron-api

On certain Neutron backends such as OVN where no agents are used,
it's unnecessary to have (so many)RPC workers running. This patch is
decoupling the number of API and RPC workers for neutron server.

In the case that the new NeutronRpcWorkers parameter is not defined,
it'll take the value of NeutronWorkers so that we don't introduce
any regression if some environments don't define it.

Change-Id: I0a3b78947fdeda638d0756f08b577d4351f371e0
Partial-Bug: #1786952
Signed-off-by: Daniel Alvarez <dalvarez@redhat.com>

puppet/services/neutron-api.yaml

@@ -33,7 +33,7 @@ parameters:
   NeutronWorkers:
     default: ''
     description: |
-      Sets the number of API and RPC workers for the Neutron service.
+      Sets the number of API workers for the Neutron service.
       The default value results in the configuration being left unset
       and a system-dependent default will be chosen (usually the number
       of processors). Please note that this can result in a large number
@@ -41,6 +41,15 @@ parameters:
       count. On such systems it is recommended that a non-default value
       be selected that matches the load requirements.
     type: string
+  NeutronRpcWorkers:
+    default: ''
+    description: |
+      Sets the number of RPC workers for the Neutron service.
+      If not specified, it'll take the value of NeutronWorkers and if this is
+      not specified either, the default value results in the configuration
+      being left unset and a system-dependent default will be chosen
+      (usually 1).
+    type: string
   NeutronPassword:
     description: The password for the neutron service and db account, used by neutron agents.
     type: string
@@ -112,6 +121,7 @@ parameter_groups:
 conditions:
   use_tls_proxy: {equals : [{get_param: EnableInternalTLS}, true]}
   neutron_workers_unset: {equals : [{get_param: NeutronWorkers}, '']}
+  neutron_rpc_workers_unset: {equals : [{get_param: NeutronRpcWorkers}, '']}
   neutron_ovs_int_br_unset: {equals : [{get_param: NeutronOvsIntegrationBridge}, '']}
 
 resources:
@@ -217,7 +227,15 @@ outputs:
             - neutron_workers_unset
             - {}
             - neutron::server::api_workers: {get_param: NeutronWorkers}
-              neutron::server::rpc_workers: {get_param: NeutronWorkers}
+          -
+            if:
+            - neutron_rpc_workers_unset
+            -
+              if:
+              - neutron_workers_unset
+              - {}
+              - neutron::server::rpc_workers: {get_param: NeutronWorkers}
+            - neutron::server::rpc_workers: {get_param: NeutronRpcWorkers}
           -
             if:
             - neutron_ovs_int_br_unset

releasenotes/notes/decoupling_api_rpc_workers_neutron_api-eb5820d6bcedb53b.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Now it's possible to define the number of API and RPC workers separately
+    for neutron-api service. This is good for certain network backends such
+    as OVN that don't require RPC communication.