Add sample for cloudevents-nodejs

Signed-off-by: Carlos Santana <[email protected]>

Author: Carlos Santana

docs/serving/samples/cloudevents/cloudevents-nodejs/.dockerignore

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+Dockerfile
+README.md
+node_modules/
+npm-debug.log

docs/serving/samples/cloudevents/cloudevents-nodejs/.gitignore

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+node_modules/
+npm-debug.log*

docs/serving/samples/cloudevents/cloudevents-nodejs/Dockerfile

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+FROM registry.access.redhat.com/ubi8/nodejs-12
+
+# Copy application dependency manifests to the container image.
+# A wildcard is used to ensure both package.json AND package-lock.json are copied.
+# Copying this separately prevents re-running npm install on every code change.
+COPY package*.json ./
+
+# Use ci is faster and more reliable following package-lock.json
+RUN npm ci --only=production
+
+# Doc port listening port
+ENV PORT 8080
+
+EXPOSE $PORT
+
+ARG ENV=production
+
+ENV NODE_ENV $ENV
+
+# Run the web service on container startup.
+CMD npm run $NODE_ENV
+
+# Copy local code to the container image.
+COPY . ./

docs/serving/samples/cloudevents/cloudevents-nodejs/README.md

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+---
+title: "Cloud Events - Node.js"
+linkTitle: "Node.js"
+weight: 1
+type: "docs"
+---
+
+A simple web app written in Node.js that can receive and send Cloud Events that you
+can use for testing. It supports running in two modes:
+
+1. The default mode has the app reply to your input events with the output
+   event, which is simplest for demonstrating things working in isolation, but
+   is also the model for working for the Knative Eventing `Broker` concept.
+
+2. `K_SINK` mode has the app send events to the destination encoded in
+   `$K_SINK`, which is useful to demonstrate how folks can synthesize events to
+   send to a Service or Broker when not initiated by a Broker invocation (e.g.
+   implementing an event source)
+
+The application will use `$K_SINK`-mode whenever the environment variable is
+specified.
+
+Follow the steps below to create the sample code and then deploy the app to your
+cluster. You can also download a working copy of the sample, by running the
+following commands:
+
+```shell
+git clone -b "{{< branch >}}" https://github.com/knative/docs knative-docs
+cd knative-docs/docs/serving/samples/cloudevents/cloudevents-nodejs
+```
+
+## Before you begin
+
+- A Kubernetes cluster with Knative installed and DNS configured. Follow the
+  [installation instructions](../../../../install/README.md) if you need to
+  create one.
+- [Docker](https://www.docker.com) installed and running on your local machine,
+  and a Docker Hub account configured (we'll use it for a container registry).
+
+## The sample code.
+
+1. If you look in `index.js`, you will see two key functions for the
+   different modes of operation:
+
+   ```js
+   const receiveAndSend = (cloudEvent, res) => {
+     // This is called whenever an event is received if $K_SINK is set, and sends a new event
+     // to the url in $K_SINK.
+   }
+
+   const receiveAndReply = (cloudEvent, res) => {
+     // This is called whenever an event is received if $K_SINK is NOT set, and it replies with
+     // the new event instead.
+   }
+   ```
+
+1. If you look in `Dockerfile`, you will see how the dependencies are installed using npm.
+  You can build and push this to your registry of choice via:
+
+   ```shell
+   docker build -t <image> .
+   docker push <image>
+   ```
+
+1. If you look in `service.yaml`, take the `<image>` name above and insert it
+   into the `image:`.
+
+   ```shell
+   kubectl apply -f service.yaml
+   ```
+
+## Testing the sample
+
+Get the URL for your Service with:
+
+```shell
+$ kubectl get ksvc
+NAME                 URL                                                LATESTCREATED              LATESTREADY                READY   REASON
+cloudevents-nodejs   http://cloudevents-nodejs.default.1.2.3.4.xip.io   cloudevents-nodejs-ss5pj   cloudevents-nodejs-ss5pj   True
+```
+
+Then send a cloud event to it with:
+
+```shell
+$ curl -X POST \
+    -H "content-type: application/json"  \
+    -H "ce-specversion: 1.0"  \
+    -H "ce-source: curl-command"  \
+    -H "ce-type: curl.demo"  \
+    -H "ce-id: 123-abc"  \
+    -d '{"name":"Dave"}' \
+    http://cloudevents-nodejs.default.1.2.3.4.xip.io
+```
+
+You will get back:
+
+```shell
+{"message":"Hello, Dave"}
+```
+
+## Removing the sample app deployment
+
+To remove the sample app from your cluster, delete the service record:
+
+```shell
+kubectl delete --filename service.yaml
+```

docs/serving/samples/cloudevents/cloudevents-nodejs/index.js

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+const express = require('express')
+const { CloudEvent, HTTPReceiver } = require('cloudevents-sdk')
+const HTTPBinary = require('cloudevents-sdk/lib/bindings/http/emitter_binary_1.js')
+const PORT = process.env.PORT || 8080
+const target = process.env.K_SINK
+const app = express()
+const receiver = new HTTPReceiver()
+
+const main = () => {
+  app.listen(PORT, function () {
+    console.log(`Cookie monster is hungry for some cloudevents on port ${PORT}!`)
+    const modeMessage = target ? `send cloudevents to K_SINK: ${target}` : 'reply back with cloudevents'
+    console.log(`Cookie monster is going to ${modeMessage}`)
+  })
+}
+
+// handle shared the logic for producing the Response event from the Request.
+const handle = (data) => {
+  return { message: `Hello, ${data.name ? data.name : 'nameless'}` }
+}
+
+// receiveAndSend is invoked whenever we receive an event.
+const receiveAndSend = (cloudEvent, res) => {
+  const newCloudEvent = new CloudEvent()
+    .type('dev.knative.docs.sample')
+    .source('https://github.com/knative/docs/docs/serving/samples/cloudevents/cloudevents-nodejs')
+    .time(new Date())
+
+  const body = handle(cloudEvent.getData())
+  newCloudEvent.data(body)
+  const emitter = new HTTPBinary({
+    method: 'POST',
+    url: target
+  }).emitter
+  res.status(201).end()
+  emitter.emit(newCloudEvent).then((res) => {
+    console.log(`Sent event: ${JSON.stringify(newCloudEvent.format(), null, 2)}`)
+    console.log(`K_SINK responded: ${JSON.stringify({ status: res.status, headers: res.headers, data: res.data }, null, 2)}`)
+  })
+}
+
+// receiveAndReply is invoked whenever we receive an event.
+const receiveAndReply = (cloudEvent, res) => {
+  const newCloudEvent = new CloudEvent()
+    .type('dev.knative.docs.sample')
+    .source('https://github.com/knative/docs/docs/serving/samples/cloudevents/cloudevents-nodejs')
+    .time(new Date())
+
+  const body = handle(cloudEvent.getData())
+  newCloudEvent.data(body)
+  console.log(`Reply event: ${JSON.stringify(newCloudEvent.format(), null, 2)}`)
+  res.set(getHeaders(newCloudEvent))
+  res.status(200).send(body)
+}
+
+const getHeaders = (cloudEvent) => {
+  /* TODO: This function should be provided by sdk */
+  const emitter = new HTTPBinary().emitter
+  const headers = {}
+  Object.keys(emitter.headerByGetter)
+    .filter((getter) => cloudEvent[getter]())
+    .forEach((getter) => {
+      const header = emitter.headerByGetter[getter]
+      headers[header.name] =
+        header.parser(
+          cloudEvent[getter]()
+        )
+    })
+  return headers
+}
+
+app.use((req, res, next) => {
+  let data = ''
+  req.setEncoding('utf8')
+  req.on('data', function (chunk) {
+    data += chunk
+  })
+  req.on('end', function () {
+    req.body = data
+    next()
+  })
+})
+
+app.post('/', function (req, res) {
+  try {
+    const event = receiver.accept(req.headers, req.body)
+    console.log(`Accepted event: ${JSON.stringify(event.format(), null, 2)}`)
+    target ? receiveAndSend(event, res) : receiveAndReply(event, res)
+  } catch (err) {
+    console.error(err)
+    res.status(415)
+      .header('Content-Type', 'application/json')
+      .send(JSON.stringify(err))
+  }
+})
+
+main()