Only generate Octavia certs on stack create

We are regenerating octavia certs whenever an overcloud is updated,
breaking any deployments using the auto-generated certs. Certificate
updates after the initial deployment require special handling and
shouldn't be performed by stack updates/upgrades at this time.

Note: depends on changed because the dependent patch was a semantic
backport.

Depends-On: I8088a0a42094b2d038ba29779535a05195138747
Closes-Bug: #1838039
Change-Id: I05f69df627e5637fdb254285cb3ad6d3d8328f90
(cherry picked from commit b611567855)
(cherry picked from commit 2f4dd2c927)
(cherry picked from commit 82bfea421e)

docker/services/octavia/octavia-deployment-config.yaml

@@ -30,6 +30,13 @@ parameters:
     description: Mapping of service endpoint -> protocol. Typically set
                  via parameter_defaults in the resource registry.
     type: json
+  StackAction:
+    type: string
+    description: >
+      Heat action on performed top-level stack.  Note StackUpdateType is
+      set to UPGRADE when a major-version upgrade is in progress.
+    constraints:
+    - allowed_values: ['CREATE', 'UPDATE']
   OctaviaPostWorkflowName:
     description: Mistral workflow name for octavia configuration steps
                  once the overcloud is ready.
@@ -159,6 +166,13 @@ parameters:
     type: string
     default: 'service'
 
+  generate_certs:
+      and:
+      - get_param: OctaviaGenerateCerts
+      - equals:
+        - get_param: StackAction
+        - CREATE
+
 resources:
   default_key_pair:
     type: OS::Nova::KeyPair
@@ -202,7 +216,7 @@ outputs:
               ca_private_key_path: { get_param: OctaviaCaKeyFile }
               ca_passphrase: { get_param: OctaviaCaKeyPassphrase }
               client_cert_path: { get_param: OctaviaClientCertFile }
-              generate_certs: { get_param: OctaviaGenerateCerts }
+              generate_certs: {if: [generate_certs, true, false]}
               mgmt_port_dev: { get_param: OctaviaMgmtPortDevName }
               overcloud_password: { get_param: AdminPassword }
               overcloud_project: 'admin'