During startup open a connection to every configured database, to ensure all...

During startup open a connection to every configured database, to ensure all of them can indeed be accessed. This avoids surprises during runtime when traversal to some database mountpoint could fail as the underlying storage cannot be opened at all.

doc/CHANGES.rst

@@ -16,6 +16,11 @@ Bugs Fixed
 Features Added
 ++++++++++++++
 
+- During startup open a connection to every configured database, to ensure all
+  of them can indeed be accessed. This avoids surprises during runtime when
+  traversal to some database mountpoint could fail as the underlying storage
+  cannot be opened at all.
+
 - Explicitly close all databases on shutdown, which ensures `Data.fs.index`
   gets written to the file system.
 

src/Zope2/App/startup.py

@@ -93,6 +93,17 @@ def startup():
         else:
             DB = ZODB.DB(m.Storage, databases=databases)
 
+    # Force a connection to every configured database, to ensure all of them
+    # can indeed be opened. This avoids surprises during runtime when traversal
+    # to some database mountpoint fails as the underlying storage cannot be
+    # opened at all
+    for mount, name in dbtab.listMountPaths():
+        _db = dbtab.getDatabase(mount)
+        _conn = _db.open()
+        _conn.close()
+        del _conn
+        del _db
+
     notify(DatabaseOpened(DB))
 
     Globals.BobobaseName = DB.getName()