Set non-0 disk sizes for tempest flavors

Nova change https://review.openstack.org/603910/ is
going to change the default rule on policy
os_compute_api:servers:create:zero_disk_flavor to
admin-only, which will prevent non-admins from
creating image-backed servers with a flavor that
has disk=0 since it's a potential security exposure.

Therefore we need the test flavors that are created
for tempest to use non-0 disk values. Since the flavor_ref
and flavor_ref_alt can be aligned to the image_ref and
image_ref_alt in tempest.conf, we get the image sizes
from glance (in bytes) and convert those to GiB disk
sizes for each flavor, respectively. Since we're using
Cirros images by default, we need to make sure to round
up otherwise we'd still have a 0-disk flavor.

There are lots of ways the math could be done here
using numfmt, bash, awk, bc, etc, but it's simplest to
write and probably easiest to read by using python for
the size conversion code.

Change-Id: I537c299b0cd400982189f35b31df74755422737e
Related-Bug: #1739646

Author: mriedem

lib/tempest

@@ -102,6 +102,14 @@ function remove_disabled_extensions {
     remove_disabled_services "$extensions_list" "$disabled_exts"
 }
 
+# image_size_in_gib - converts an image size from bytes to GiB, rounded up
+# Takes an image ID parameter as input
+function image_size_in_gib {
+    local size
+    size=$(openstack image show $1 -c size -f value)
+    echo $size | python -c "import math; print int(math.ceil(float(int(raw_input()) / 1024.0 ** 3)))"
+}
+
 # configure_tempest() - Set config files, create data dirs, etc
 function configure_tempest {
     if [[ "$INSTALL_TEMPEST" == "True" ]]; then
@@ -125,6 +133,7 @@ function configure_tempest {
     local public_network_id
     local public_router_id
     local ssh_connect_method="floating"
+    local disk
 
     # Save IFS
     ifs=$IFS
@@ -190,11 +199,15 @@ function configure_tempest {
         available_flavors=$(nova flavor-list)
         if  [[ -z "$DEFAULT_INSTANCE_TYPE" ]]; then
             if [[ ! ( $available_flavors =~ 'm1.nano' ) ]]; then
-                openstack flavor create --id 42 --ram 64 --disk 0 --vcpus 1 m1.nano
+                # Determine the flavor disk size based on the image size.
+                disk=$(image_size_in_gib $image_uuid)
+                openstack flavor create --id 42 --ram 64 --disk $disk --vcpus 1 m1.nano
             fi
             flavor_ref=42
             if [[ ! ( $available_flavors =~ 'm1.micro' ) ]]; then
-                openstack flavor create --id 84 --ram 128 --disk 0 --vcpus 1 m1.micro
+                # Determine the alt flavor disk size based on the alt image size.
+                disk=$(image_size_in_gib $image_uuid_alt)
+                openstack flavor create --id 84 --ram 128 --disk $disk --vcpus 1 m1.micro
             fi
             flavor_ref_alt=84
         else