Allow using default images values for EDPM

With this patch we'll be able to allow using the default values for
`registry_url`, `image_prefix` and `image_tag` when the values for their
corresponding variables are empty.

scripts/gen-edpm-kustomize.sh

@@ -103,23 +103,38 @@ cat <<EOF >>kustomization.yaml
 EOF
 fi
 
+if [ -n "$EDPM_REGISTRY_URL" ]; then
 cat <<EOF >>kustomization.yaml
-    - op: replace
-      path: /spec/nodeTemplate/ansible/ansibleVars/timesync_ntp_servers
-      value:
-        - {hostname: ${EDPM_NTP_SERVER}}
-    - op: replace
-      path: /spec/nodeTemplate/ansible/ansibleVars/neutron_public_interface_name
-      value: ${EDPM_NETWORK_INTERFACE_NAME}
     - op: replace
       path: /spec/nodeTemplate/ansible/ansibleVars/registry_url
       value: ${EDPM_REGISTRY_URL}
+EOF
+fi
+
+if [ -n "$EDPM_CONTAINER_PREFIX" ]; then
+cat <<EOF >>kustomization.yaml
     - op: replace
       path: /spec/nodeTemplate/ansible/ansibleVars/image_prefix
       value: ${EDPM_CONTAINER_PREFIX}
+EOF
+fi
+
+if [ -n "$EDPM_CONTAINER_TAG" ]; then
+cat <<EOF >>kustomization.yaml
     - op: replace
       path: /spec/nodeTemplate/ansible/ansibleVars/image_tag
       value: ${EDPM_CONTAINER_TAG}
+EOF
+fi
+
+cat <<EOF >>kustomization.yaml
+    - op: replace
+      path: /spec/nodeTemplate/ansible/ansibleVars/timesync_ntp_servers
+      value:
+        - {hostname: ${EDPM_NTP_SERVER}}
+    - op: replace
+      path: /spec/nodeTemplate/ansible/ansibleVars/neutron_public_interface_name
+      value: ${EDPM_NETWORK_INTERFACE_NAME}
     - op: replace
       path: /spec/nodeTemplate/ansible/ansibleVars/edpm_sshd_allowed_ranges
       value: ${EDPM_SSHD_ALLOWED_RANGES}