Add a priority mechanism for docker images providing the same environments

beat/core/dock.py

@@ -68,7 +68,7 @@ class Host(object):
 
     self.client = docker.Client(**self.kwargs)
 
-    self.environments = self._discover_environments(raise_on_errors=True)
+    self.environments = self._discover_environments(raise_on_errors=False)
 
     # makes sure we can talk to the docker host
     assert self.ip
@@ -165,11 +165,62 @@ class Host(object):
                   "uniquely named. Fix this and re-start." % \
                   (tag or id, retval[key]['image'], key))
         else:
-          logger.warn("Overriding **existing** environment `%s' image " \
-                  "with `%s' (it was `%s). To avoid this warning make " \
-                  "sure your docker images do not contain environments " \
-                  "with the same names", key, retval[key]['image'],
-                  image['Id'])
+          new_version = None
+          previous_version = None
+
+          parts = tag.split('/')
+          if len(parts) > 1:
+            parts = parts[-1].split(':')
+            if len(parts) > 1:
+              new_version = parts[-1]
+
+          parts = retval[key]['tag'].split('/')
+          if len(parts) > 1:
+            parts = parts[-1].split(':')
+            if len(parts) > 1:
+              previous_version = parts[-1]
+
+          replacement = False
+          keep = False
+
+          if (new_version is not None) and (previous_version is not None):
+            if new_version == 'latest':
+              replacement = True
+            elif previous_version == 'latest':
+              keep = True
+            else:
+              try:
+                new_version = tuple([ int(x) for x in new_version.split('.') ])
+
+                try:
+                  previous_version = tuple([ int(x) for x in previous_version.split('.') ])
+
+                  if new_version > previous_version:
+                    replacement = True
+                  else:
+                    keep = True
+                except:
+                  replacement = True
+
+              except:
+                keep = True
+
+          elif new_version is not None:
+            replacement = True
+          elif previous_version is not None:
+            keep = True
+
+          if replacement:
+            logger.debug("Overriding **existing** environment `%s' in image `%s'", key, retval[key]['tag'])
+          elif keep:
+            logger.debug("Environment `%s' already existing in image `%s', we'll keep it", key, retval[key]['tag'])
+            continue
+          else:
+            logger.warn("Overriding **existing** environment `%s' image " \
+                    "with `%s' (it was `%s). To avoid this warning make " \
+                    "sure your docker images do not contain environments " \
+                    "with the same names", key, retval[key]['image'],
+                    image['Id'])
 
       retval[key] = description
       retval[key]['image'] = image['Id']