Add an exception for unsupported middleware wrapping for better failure

handling.

lib/galaxy/webapps/galaxy/buildapp.py

@@ -19,7 +19,12 @@ import galaxy.model.mapping
 import galaxy.datatypes.registry
 import galaxy.web.framework
 import galaxy.web.framework.webapp
-from galaxy.webapps.util import build_template_error_formatters, wrap_if_allowed
+from galaxy.webapps.util import (
+    MiddlewareWrapUnsupported,
+    build_template_error_formatters,
+    wrap_if_allowed,
+    wrap_if_allowed_or_fail
+)
 from galaxy import util
 from galaxy.util import asbool
 from galaxy.util.properties import load_app_properties
@@ -912,13 +917,15 @@ def wrap_in_middleware( app, global_conf, application_stack, **local_conf ):
         # Interactive exception debugging, scary dangerous if publicly
         # accessible, if not enabled we'll use the regular error printing
         # middleware.
-        from weberror import evalexception
-        import galaxy.web.framework.middleware.error
-        app = wrap_if_allowed( app, stack, evalexception.EvalException,
-                               args=(conf,),
-                               kwargs=dict(templating_formatters=build_template_error_formatters()),
-                               alt_wrap=galaxy.web.framework.middleware.error.ErrorMiddleware,
-                               alt_args=(conf,) )
+        try:
+            from weberror import evalexception
+            app = wrap_if_allowed_or_fail( app, stack, evalexception.EvalException,
+                                           args=(conf,),
+                                           kwargs=dict(templating_formatters=build_template_error_formatters()) )
+        except MiddlewareWrapUnsupported as exc:
+            log.warning(str(exc))
+            import galaxy.web.framework.middleware.error
+            app = wrap_if_allowed( app, stack, galaxy.web.framework.middleware.error.ErrorMiddleware, args=(conf,) )
     else:
         # Not in interactive debug mode, just use the regular error middleware
         import galaxy.web.framework.middleware.error

lib/galaxy/webapps/reports/buildapp.py

@@ -11,8 +11,12 @@ from inspect import isclass
 from paste import httpexceptions
 
 from galaxy.util import asbool
-from galaxy.webapps.util import build_template_error_formatters, wrap_if_allowed
-
+from galaxy.webapps.util import (
+    MiddlewareWrapUnsupported,
+    build_template_error_formatters,
+    wrap_if_allowed,
+    wrap_if_allowed_or_fail
+)
 import galaxy.model
 import galaxy.model.mapping
 import galaxy.web.framework.webapp
@@ -119,13 +123,15 @@ def wrap_in_middleware( app, global_conf, application_stack, **local_conf ):
         # Interactive exception debugging, scary dangerous if publicly
         # accessible, if not enabled we'll use the regular error printing
         # middleware.
-        from weberror import evalexception
-        import galaxy.web.framework.middleware.error
-        app = wrap_if_allowed( app, stack, evalexception.EvalException,
-                               args=(conf,),
-                               kwargs=dict(templating_formatters=build_template_error_formatters()),
-                               alt_wrap=galaxy.web.framework.middleware.error.ErrorMiddleware,
-                               alt_args=(conf,) )
+        try:
+            from weberror import evalexception
+            app = wrap_if_allowed_or_fail( app, stack, evalexception.EvalException,
+                                           args=(conf,),
+                                           kwargs=dict(templating_formatters=build_template_error_formatters()) )
+        except MiddlewareWrapUnsupported as exc:
+            log.warning(str(exc))
+            import galaxy.web.framework.middleware.error
+            app = wrap_if_allowed( app, stack, galaxy.web.framework.middleware.error.ErrorMiddleware, args=(conf,) )
     else:
         # Not in interactive debug mode, just use the regular error middleware
         import galaxy.web.framework.middleware.error

lib/galaxy/webapps/tool_shed/buildapp.py

@@ -14,7 +14,12 @@ from galaxy.util import asbool
 import galaxy.webapps.tool_shed.model
 import galaxy.webapps.tool_shed.model.mapping
 import galaxy.web.framework.webapp
-from galaxy.webapps.util import build_template_error_formatters, wrap_if_allowed
+from galaxy.webapps.util import (
+    MiddlewareWrapUnsupported,
+    build_template_error_formatters,
+    wrap_if_allowed,
+    wrap_if_allowed_or_fail
+)
 from galaxy import util
 from galaxy.util.properties import load_app_properties
 from routes.middleware import RoutesMiddleware
@@ -237,13 +242,16 @@ def wrap_in_middleware( app, global_conf, application_stack, **local_conf ):
         # Interactive exception debugging, scary dangerous if publicly
         # accessible, if not enabled we'll use the regular error printing
         # middleware.
-        from weberror import evalexception
-        import galaxy.web.framework.middleware.error
-        app = wrap_if_allowed( app, stack, evalexception.EvalException,
-                               args=(conf,),
-                               kwargs=dict(templating_formatters=build_template_error_formatters()),
-                               alt_wrap=galaxy.web.framework.middleware.error.ErrorMiddleware,
-                               alt_args=(conf,) )
+        try:
+            from weberror import evalexception
+            app = wrap_if_allowed_or_fail( app, stack, evalexception.EvalException,
+                                           args=(conf,),
+                                           kwargs=dict(templating_formatters=build_template_error_formatters()) )
+        except MiddlewareWrapUnsupported as exc:
+            log.warning(str(exc))
+            import galaxy.web.framework.middleware.error
+            app = wrap_if_allowed( app, stack, galaxy.web.framework.middleware.error.ErrorMiddleware, args=(conf,) )
+
     else:
         # Not in interactive debug mode, just use the regular error middleware
         import galaxy.web.framework.middleware.error

lib/galaxy/webapps/util.py

@@ -8,6 +8,10 @@ import mako.exceptions
 log = logging.getLogger(__name__)
 
 
+class MiddlewareWrapUnsupported(Exception):
+    pass
+
+
 def build_template_error_formatters():
     """
     Build a list of template error formatters for WebError. When an error
@@ -26,8 +30,26 @@ def build_template_error_formatters():
     return formatters
 
 
-def wrap_if_allowed(app, stack, wrap, name=None, args=None, kwargs=None,
-                    alt_wrap=None, alt_name=None, alt_args=None, alt_kwargs=None):
+def wrap_if_allowed_or_fail(app, stack, wrap, name=None, args=None, kwargs=None):
+    """
+    Wrap the application with the given method if the application stack allows for it.
+
+    Arguments are the same as for :func:`wrap_if_allowed`.
+
+    Raises :exception:`MiddlewareWrapUnsupported` if the stack does not allow the middleware.
+    """
+    name = name or wrap.__name__
+    if not stack.allowed_middleware(wrap):
+        raise MiddlewareWrapUnsupported(
+            "'%s' is enabled in your configuration but the %s application stack does not support it, this "
+            "middleware has been disabled" % (name, stack.name))
+    args = args or []
+    kwargs = kwargs or {}
+    log.debug("Enabling '%s' middleware", name)
+    return wrap(app, *args, **kwargs)
+
+
+def wrap_if_allowed(app, stack, wrap, name=None, args=None, kwargs=None):
     """
     Wrap the application with the given method if the application stack allows for it.
 
@@ -43,16 +65,11 @@ def wrap_if_allowed(app, stack, wrap, name=None, args=None, kwargs=None,
     :param  args:   arguments to pass to `wrap` (not including `app` itself)
     :type   kwargs: dict
     :param  kwargs: keyword arguments to pass to `wrap`
+
+    Returns `app` unmodified if the stack does not allow the middleware.
     """
-    name = name or wrap.__name__
-    if stack.allowed_middleware(wrap):
-        args = args or []
-        kwargs = kwargs or {}
-        log.debug("Enabling '%s' middleware", name)
-        return wrap(app, *args, **kwargs)
-    else:
-        log.warning("'%s' is enabled in your configuration but the %s application stack does not support it, this "
-                    "middleware has been disabled", name, stack.name)
-        if alt_wrap:
-            app = wrap_if_allowed(app, stack, alt_wrap, name=alt_name, args=alt_args, kwargs=alt_kwargs)
+    try:
+        return wrap_if_allowed_or_fail(app, stack, wrap, name=name, args=args, kwargs=kwargs)
+    except MiddlewareWrapUnsupported as exc:
+        log.warning(str(exc))
         return app