Add README to python env

environments/python3/README.md

@@ -0,0 +1,44 @@
+# Fission: Python Environment
+
+This is the Python environment for Fission.
+
+It's a Docker image containing a Python 3.5 runtime, along with a
+dynamic loader.  A few common dependencies are included in the
+requirements.txt file.
+
+## Customizing this image
+
+Most commonly you might want to add package dependencies.  Edit
+requirements.txt to add what you need, and rebuild this image.
+
+You also may want to customize what's available to the function in its
+context.  You can do this by editing server.py.
+
+## Rebuilding and pushing the image
+
+You'll need access to a Docker registry to push the image: you can
+sign up for Docker hub at hub.docker.com, or use registries from
+gcr.io, quay.io, etc.  Let's assume you're using a docker hub account
+called USER.  Build and push the image to the the registry:
+
+```
+   docker build -t USER/python-env . && docker push USER/python-env
+```
+
+## Using the image in fission
+
+You can add this customized image to fission with "fission env
+create":
+
+```
+   fission env create --name python --image USER/python-env
+```
+
+Or, if you already have an environment, you can update its image:
+
+```
+   fission env update --name python --image USER/python-env   
+```
+
+After this, fission functions that have the env parmeter set to the
+same environment name as this command will use this environment.

environments/python3/server.py

@@ -4,9 +4,7 @@ import logging
 import sys
 import imp
 
-from flask import Flask
-from flask import request
-from flask import abort
+from flask import Flask, request, abort, g
 
 app = Flask(__name__)
 
@@ -25,6 +23,11 @@ def f():
     if userfunc == None:
         print("Generic container: no requests supported")
         abort(500)
+    #
+    # If you want to pass something to the function, you can add it to 'g':
+    #   g.myKey = myValue
+    # And the user func can then access that (after doing a "from flask import g").
+    #
     return userfunc()
 
 #