Rework database template downloading.

 - Only use latest strategy introduced in 053be7e if we have just downloaded the latet verion of Galaxy.
 - Otherwise, look at Galaxy's migrations and pick the newest download that planemo is sure will work.

This fixes planemo for stable versions of Galaxy (and a little older) but the long term solution going forward is to move this functionality into Galaxy (since Galaxy should know pretty clearly what version of the database it is on).

planemo/galaxy_config.py

@@ -70,6 +70,7 @@
 
 DOWNLOADS_URL = ("https://raw.githubusercontent.com/"
                  "jmchilton/galaxy-downloads/master/")
+DOWNLOADABLE_MIGRATION_VERSIONS = [127, 120, 117]
 LATEST_URL = DOWNLOADS_URL + "latest.sqlite"
 
 FAILED_TO_FIND_GALAXY_EXCEPTION = (
@@ -106,7 +107,9 @@ def config_join(*args):
         created_config_directory = True
         config_directory = mkdtemp()
     try:
+        latest_galaxy = False
         if __install_galaxy_if_needed(config_directory, kwds):
+            latest_galaxy = True
             galaxy_root = config_join("galaxy-central-master")
 
         __handle_dependency_resolution(config_directory, kwds)
@@ -118,9 +121,13 @@ def config_join(*args):
         preseeded_database = True
 
         try:
-            template_url = DOWNLOADS_URL + urllib.urlopen(LATEST_URL).read()
-            urlretrieve(template_url, database_location)
-        except Exception:
+            _download_database_template(
+                galaxy_root,
+                database_location,
+                latest=latest_galaxy
+            )
+        except Exception as e:
+            print e
             # No network access - just roll forward from null.
             preseeded_database = False
 
@@ -200,6 +207,41 @@ def config_join(*args):
             shutil.rmtree(config_directory)
 
 
+def _download_database_template(galaxy_root, database_location, latest=False):
+    if latest:
+        template_url = DOWNLOADS_URL + urllib.urlopen(LATEST_URL).read()
+        urlretrieve(template_url, database_location)
+        return True
+
+    newest_migration = _newest_migration_version(galaxy_root)
+    download_migration = None
+    for migration in DOWNLOADABLE_MIGRATION_VERSIONS:
+        if newest_migration > migration:
+            download_migration = migration
+            break
+
+    if download_migration:
+        download_name = "db_gx_rev_0%d.sqlite" % download_migration
+        download_url = DOWNLOADS_URL + download_name
+        urlretrieve(download_url, database_location)
+        return True
+    else:
+        return False
+
+
+def _newest_migration_version(galaxy_root):
+    versions = os.path.join(galaxy_root, "lib/galaxy/model/migrate/versions")
+    version = max(map(_file_name_to_migration_version, os.listdir(versions)))
+    return version
+
+
+def _file_name_to_migration_version(name):
+    try:
+        return int(name[0:4])
+    except ValueError:
+        return -1
+
+
 def __find_galaxy_root(ctx, **kwds):
     galaxy_root = kwds.get("galaxy_root", None)
     if galaxy_root: