Add README to NodeJS env

environments/nodejs/README.md

@@ -0,0 +1,45 @@
+# Fission: NodeJS Environment
+
+This is the NodeJS environment for Fission.
+
+It's a Docker image containing a NodeJS runtime, along with a dynamic
+loader.  A few common dependencies are included in the package.json
+file.
+
+## Customizing this image
+
+To add package dependencies, edit package.json to add what you need,
+and rebuild this image (instructions below).
+
+You also may want to customize what's available to the function in its
+request context.  You can do this by editing `server.js` (see the
+comment in that file about customizing request context).
+
+## 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/nodejs-env . && docker push USER/nodejs-env
+```
+
+## Using the image in fission
+
+You can add this customized image to fission with "fission env
+create":
+
+```
+   fission env create --name nodejs --image USER/nodejs-env
+```
+
+Or, if you already have an environment, you can update its image:
+
+```
+   fission env update --name nodejs --image USER/nodejs-env   
+```
+
+After this, fission functions that have the env parameter set to the
+same environment name as this command will use this environment.

environments/nodejs/server.js

@@ -80,6 +80,12 @@ app.all('/', function (req, res) {
         res.status(status).send(body);
     }
     try {
+        //
+        // Customizing the request context
+        //
+        // If you want to modify the context to add anything to it,
+        // you can do that here by adding properties to the context.
+        //
         userFunction(context, callback);
     } catch(e) {
         console.log(`Function error: ${e}`);