Tuning pool_recycle to avoid MySQL server gone away

Some time after lodgeit application have no load
SQLalchemy connection expires and application dies
with 5xx error and MySQL Server gone away exception.

By using a shorter default pool_recycle of 3600s which
can also be tweaked using environment variables, it allows
you to avoid dealing with this issue.

Change-Id: I79eb823458c604b2faff9bb1e9531c45fc1ed3cb

lodgeit/application.py

@@ -24,11 +24,12 @@ from lodgeit.controllers import get_controller
 class LodgeIt(object):
     """The WSGI Application"""
 
-    def __init__(self, dburi, secret_key):
+    def __init__(self, dburi, secret_key, pool_recycle=3600):
         self.secret_key = secret_key
 
         #: bind metadata, create engine and create all tables
-        self.engine = engine = create_engine(dburi, convert_unicode=True)
+        self.engine = engine = create_engine(
+            dburi, convert_unicode=True, pool_recycle=pool_recycle)
         db.metadata.bind = engine
         db.metadata.create_all(engine, [Paste.__table__])
 
@@ -84,7 +85,8 @@ def make_app(dburi=None, secret_key=None, debug=False, shell=False):
         secret_key = os.getenv('LODGEIT_SECRET_KEY')
 
     static_path = os.path.join(os.path.dirname(__file__), 'static')
-    app = LodgeIt(dburi, secret_key)
+    app = LodgeIt(dburi, secret_key,
+                  pool_recycle=os.getenv('LODGEIT_POOL_RECYCLE', 3600))
     if debug:
         app.engine.echo = True
     app.bind_to_context()