support the new devstack image finder

if the new devstack image_list.sh tool is found, use that are our
definitive image collection API out of devstack. We fall back to
the old method if it's not found, or fails to execute cleanly.

Change-Id: I9c59ac505b0a1085add76bfc6cb1b14e5545fc28

modules/openstack_project/files/nodepool/scripts/cache_devstack.py

@@ -17,6 +17,7 @@
 # limitations under the License.
 
 import os
+import subprocess
 import sys
 
 from common import run_local
@@ -48,6 +49,46 @@ def tokenize(fn, tokens, distribution, comment=None):
             tokens.append(line)
 
 
+def _legacy_find_images(basedir):
+    """Divine what images we should use based on parsing stackrc."""
+    images = []
+    for line in open(os.path.join(DEVSTACK, 'stackrc')):
+        line = line.strip()
+        if line.startswith('IMAGE_URLS'):
+            if '#' in line:
+                line = line[:line.rfind('#')]
+            if line.endswith(';;'):
+                line = line[:-2]
+            line = line.split('=', 1)[1].strip()
+            if line.startswith('${IMAGE_URLS:-'):
+                line = line[len('${IMAGE_URLS:-'):]
+            if line.endswith('}'):
+                line = line[:-1]
+            if not line:
+                continue
+            if line[0] == line[-1] == '"':
+                line = line[1:-1]
+            # Add image to the list to be downloaded, but
+            # skip downloading giant vmware images
+            images += [x.strip() for x in line.split(',')
+                       if not x.strip().endswith('vmdk')]
+    return images
+
+
+def _find_images(basedir):
+    images = []
+    try:
+        image_tool = os.path.join(DEVSTACK, 'tools', 'image_list.sh')
+        if os.path.exist(image_tool):
+            images = subprocess.check_output(image_tool).split('\n')
+    except subprocess.CalledProcessError as ce:
+        print "image_list.sh failed"
+        print "Exit: %s, Output: %s" % (ce.returncode, ce.output)
+        # reset images so we'll fall back
+        images = []
+    return images
+
+
 def local_prep(distribution):
     branches = []
     for branch in git_branches():
@@ -79,27 +120,10 @@ def local_prep(distribution):
                 tokenize(fn, rpms, distribution, comment='#')
             branch_data['rpms'] = rpms
 
-        images = []
-        for line in open(os.path.join(DEVSTACK, 'stackrc')):
-            line = line.strip()
-            if line.startswith('IMAGE_URLS'):
-                if '#' in line:
-                    line = line[:line.rfind('#')]
-                if line.endswith(';;'):
-                    line = line[:-2]
-                line = line.split('=', 1)[1].strip()
-                if line.startswith('${IMAGE_URLS:-'):
-                    line = line[len('${IMAGE_URLS:-'):]
-                if line.endswith('}'):
-                    line = line[:-1]
-                if not line:
-                    continue
-                if line[0] == line[-1] == '"':
-                    line = line[1:-1]
-                # Add image to the list to be downloaded, but
-                # skip downloading giant vmware images
-                images += [x.strip() for x in line.split(',')
-                           if not x.strip().endswith('vmdk')]
+        images = _find_images(DEVSTACK)
+        if not images:
+            images = _legacy_find_images(DEVSTACK)
+
         branch_data['images'] = images
         branches.append(branch_data)
     return branches