Add README for Node.js examples (#155)

examples/nodejs/README.md

@@ -0,0 +1,98 @@
+# Fission Node.js Examples
+
+This directory contains several examples to get you started using Node.js with Fission.
+
+Before running any of these functions, make sure you have created a `nodejs` Fission environment:
+
+```
+$ fission env create --name nodejs --image fission/node-env
+```
+
+## Function signature
+
+Every Node.js function has the same basic form:
+
+```javascript
+module.exports = async function(context) {
+    return {
+        status: 200,
+        body: 'Your body here',
+        headers: {
+            'Foo': 'Bar'
+        }
+    }    
+}
+```
+
+Since it is an `async` function, you can `await` `Promise`s, as demonstrated in the `stock.js` function.
+
+## hello.js
+
+This is a basic "Hello, World!" example. It simply returns a status of `200` and text body.
+
+### Usage
+
+```bash
+# Upload your function code to fission
+$ fission function create --name hello --env nodejs --code hello.js
+
+# Map GET /hello to your new function
+$ fission route create --method GET --url /hello --function hello
+
+# Run the function.
+$ curl http://$FISSION_ROUTER/hello
+Hello, world!
+```
+
+## hello-callback.js
+
+This is a basic "Hello, World!" example implemented with the legacy callback implementation. If you declare your function with two arguments (`context`, `callback`), a callback taking three arguments (`status`, `body`, `headers`) is provided.
+
+⚠️️ Callback support is only provided for backwards compatibility! We recommend that you use `async` functions instead.
+
+### Usage
+
+```bash
+# Upload your function code to fission
+$ fission function create --name hello-callback --env nodejs --code hello-callback.js
+
+# Map GET /hello-callback to your new function
+$ fission route create --method GET --url /hello-callback --function hello-callback
+
+# Run the function.
+$ curl http://$FISSION_ROUTER/hello-callback
+Hello, world!
+```
+
+## stock.js
+
+This is a basic example of how you can easily use asynchronous requests in your functions. By default, the Node.js environment makes the [`request-promise-native`](https://github.com/request/request-promise-native) library available. In this example, the Google Finance API is used to determine when a stock was last traded.
+
+### Usage
+
+```bash
+# Upload your function code to fission
+$ fission function create --name stock --env nodejs --code stock.js
+
+# Map GET /stock to your new function
+$ fission route create --method GET --url /stock --function stock
+
+# Run the function.
+$ curl -H "Content-Type: application/json" -X POST -d '{"symbol":"AAPL"}' http://$FISSION_ROUTER/stock
+
+{"text":"AAPL last traded at 138.99"}
+```
+
+## kubeEventsSlack.js
+
+This example watches Kubernetes events and sends them to a Slack channel. To use this, create an incoming webhook for your Slack channel, and replace the `slackWebhookPath` in the example code.
+
+### Usage
+
+```bash
+# Upload your function code to fission
+$ fission fn create --name kubeEventsSlack --env nodejs --code kubeEventsSlack.js
+
+# Watch all services in the default namespace:
+$ fission watch create --function kubeEventsSlack --type service --ns default
+```