Setup app logger in python environment

The user's functions can now use `current_app.logger`, and use
`kubectl logs` to see the logs that the function outputs.

environments/python3/server.py

@@ -1,5 +1,7 @@
 #!/usr/bin/env python
 
+import logging
+import sys
 import imp
 
 from flask import Flask
@@ -23,10 +25,26 @@ def f():
     if userfunc == None:
         print("Generic container: no requests supported")
         abort(500)
-    return userfunc()    
+    return userfunc()
+
+#
+# Logging setup.  TODO: Loglevel hard-coded for now. We could allow
+# functions/routes to override this somehow; or we could create
+# separate dev vs. prod environments.
+#
+def setup_logger(loglevel):
+    global app
+    root = logging.getLogger()
+    root.setLevel(loglevel)
+    ch = logging.StreamHandler(sys.stdout)
+    ch.setLevel(loglevel)
+    ch.setFormatter(logging.Formatter('%(asctime)s - %(levelname)s - %(message)s'))
+    app.logger.addHandler(ch)
 
 #
 # TODO: this starts the built-in server, which isn't the most
 # efficient.  We should use something better.
 #
+setup_logger(logging.DEBUG)
+app.logger.info("Starting server")
 app.run(host='0.0.0.0', port='8888')

examples/python/requestdata.py

@@ -1,5 +1,8 @@
 from flask import request
+from flask import current_app
 
 def main():
     msg = "%s %s:\n---HEADERS---\n%s\n--BODY--\n%s\n-----\n" % (request.method, request.path, request.headers, request.get_data())
+    current_app.logger.info(msg)
+
     return msg