app.yaml

application: juno
version: 1
runtime: python
api_version: 1

handlers:
- url: .*
  script: main.py

juno-appengine.diff

diff --git a/juno.py b/juno.py
index 3dbb91b..91bf751 100644
--- a/juno.py
+++ b/juno.py
@@ -777,6 +777,5 @@ def run_wsgi(process_func):
     return get_application(process_func)
 
 def run_appengine(process_func):
-    sys.stdout = sys.stderr
     from google.appengine.ext.webapp.util import run_wsgi_app
     run_wsgi_app(get_application(process_func))

main.py

#!/usr/bin/python
# -*- coding: utf-8 -*-

from juno import *

init({'use_db': False, 'use_templates': False, 'log': False})

@get('/')
def hi(web):
    return 'Hi gae'

run(mode='appengine')