Fix create_flavors on subnodes

This makes us depend on n-api being enabled, which should avoid running
this on subnodes, where it fails because of no credentials.

Change-Id: I209bd59cd57be27c3375f5a2074361307abcafe9
Closes-Bug: #1567065
diff --git a/lib/nova b/lib/nova
index 8aca1a6..77bc3c8 100644
--- a/lib/nova
+++ b/lib/nova
@@ -934,21 +934,23 @@
 
 # create_instance_types(): Create default flavors
 function create_flavors {
-    if ! openstack flavor list | grep -q ds512M; then
-    # Note that danms hates these flavors and apologizes for sdague
-        openstack flavor create --id c1 --ram 256 --disk 0 --vcpus 1 cirros256
-        openstack flavor create --id d1 --ram 512 --disk 5 --vcpus 1 ds512M
-        openstack flavor create --id d2 --ram 1024 --disk 10 --vcpus 1 ds1G
-        openstack flavor create --id d3 --ram 2048 --disk 10 --vcpus 2 ds2G
-        openstack flavor create --id d4 --ram 4096 --disk 20 --vcpus 4 ds4G
-    fi
+    if is_service_enabled n-api; then
+        if ! openstack flavor list | grep -q ds512M; then
+            # Note that danms hates these flavors and apologizes for sdague
+            openstack flavor create --id c1 --ram 256 --disk 0 --vcpus 1 cirros256
+            openstack flavor create --id d1 --ram 512 --disk 5 --vcpus 1 ds512M
+            openstack flavor create --id d2 --ram 1024 --disk 10 --vcpus 1 ds1G
+            openstack flavor create --id d3 --ram 2048 --disk 10 --vcpus 2 ds2G
+            openstack flavor create --id d4 --ram 4096 --disk 20 --vcpus 4 ds4G
+        fi
 
-    if ! openstack flavor list | grep -q m1.tiny; then
-        openstack flavor create --id 1 --ram 512 --disk 1 --vcpus 1 m1.tiny
-        openstack flavor create --id 2 --ram 2048 --disk 20 --vcpus 1 m1.small
-        openstack flavor create --id 3 --ram 4096 --disk 40 --vcpus 2 m1.medium
-        openstack flavor create --id 4 --ram 8192 --disk 80 --vcpus 4 m1.large
-        openstack flavor create --id 5 --ram 16384 --disk 160 --vcpus 8 m1.xlarge
+        if ! openstack flavor list | grep -q m1.tiny; then
+            openstack flavor create --id 1 --ram 512 --disk 1 --vcpus 1 m1.tiny
+            openstack flavor create --id 2 --ram 2048 --disk 20 --vcpus 1 m1.small
+            openstack flavor create --id 3 --ram 4096 --disk 40 --vcpus 2 m1.medium
+            openstack flavor create --id 4 --ram 8192 --disk 80 --vcpus 4 m1.large
+            openstack flavor create --id 5 --ram 16384 --disk 160 --vcpus 8 m1.xlarge
+        fi
     fi
 }