Add sample for managing GCE instances from GCF (#815)

NodeJS 6 code sample for Cloud Function to start/stop GCE instances.

.kokoro/functions/scheduleinstance.cfg

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+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Set the folder in which the tests are run
+env_vars: {
+    key: "PROJECT"
+    value: "functions/scheduleinstance"
+}
+
+# Tell the trampoline which build file to use.
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/nodejs-docs-samples/.kokoro/build.sh"
+}

functions/scheduleinstance/README.md

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+<img src="https://avatars2.githubusercontent.com/u/2810941?v=3&s=96" alt="Google Cloud Platform logo" title="Google Cloud Platform" align="right" height="96" width="96"/>
+
+# Google Cloud Functions - Scheduling GCE Instances sample
+
+## Deploy and run the sample
+
+See the [Scheduling Instances with Cloud Scheduler tutorial][tutorial].
+
+[tutorial]: https://cloud.google.com/scheduler/docs/scheduling-instances-with-cloud-scheduler
+
+## Run the tests
+
+1. Read and follow the [prerequisites](../../#how-to-run-the-tests).
+
+1. Install dependencies:
+
+        npm install
+
+1. Run the tests:
+
+        npm test
+
+## Additional resources
+
+* [Cloud Scheduler documentation][docs]
+* [HTTP Cloud Functions documentation][http_docs]
+* [HTTP Cloud Functions tutorial][http_tutorial]
+
+[docs]: https://cloud.google.com/scheduler/docs/
+[http_docs]: https://cloud.google.com/functions/docs/writing/http
+[http_tutorial]: https://cloud.google.com/functions/docs/tutorials/http

functions/scheduleinstance/index.js

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+/**
+ * Copyright 2018, Google, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// [START functions_start_instance_http]
+// [START functions_stop_instance_http]
+const Compute = require('@google-cloud/compute');
+const compute = new Compute();
+
+// [END functions_stop_instance_http]
+/**
+ * Starts a Compute Engine instance.
+ *
+ * Expects an HTTP POST request with a request body containing the following
+ * attributes:
+ *  zone - the GCP zone the instance is located in.
+ *  instance - the name of the instance.
+ *
+ * @param {!object} req Cloud Function HTTP request data.
+ * @param {!object} res Cloud Function HTTP response data.
+ * @returns {!object} Cloud Function response data with status code and message.
+ */
+exports.startInstance = (req, res) => {
+  try {
+    const reqBody = _validateReqBody(_parseReqBody(_validateReq(req)));
+    compute.zone(reqBody.zone)
+      .vm(reqBody.instance)
+      .start()
+      .then(data => {
+        // Operation pending.
+        const operation = data[0];
+        return operation.promise();
+      })
+      .then(() => {
+        // Operation complete. Instance successfully started.
+        const message = 'Successfully started instance ' + reqBody.instance;
+        console.log(message);
+        res.status(200).send(message);
+      })
+      .catch(err => {
+        console.log(err);
+        res.status(500).send({error: err.message});
+      });
+  } catch (err) {
+    console.log(err);
+    res.status(400).send({error: err.message});
+  }
+  return res;
+};
+// [END functions_start_instance_http]
+
+// [START functions_stop_instance_http]
+/**
+ * Stops a Compute Engine instance.
+ *
+ * Expects an HTTP POST request with a request body containing the following
+ * attributes:
+ *  zone - the GCP zone the instance is located in.
+ *  instance - the name of the instance.
+ *
+ * @param {!object} req Cloud Function HTTP request data.
+ * @param {!object} res Cloud Function HTTP response data.
+ * @returns {!object} Cloud Function response data with status code and message.
+ */
+exports.stopInstance = (req, res) => {
+  try {
+    const reqBody = _validateReqBody(_parseReqBody(_validateReq(req)));
+    compute.zone(reqBody.zone)
+      .vm(reqBody.instance)
+      .stop()
+      .then(data => {
+        // Operation pending.
+        const operation = data[0];
+        return operation.promise();
+      })
+      .then(() => {
+        // Operation complete. Instance successfully stopped.
+        const message = 'Successfully stopped instance ' + reqBody.instance;
+        console.log(message);
+        res.status(200).send(message);
+      })
+      .catch(err => {
+        console.log(err);
+        res.status(500).send({error: err.message});
+      });
+  } catch (err) {
+    console.log(err);
+    res.status(400).send({error: err.message});
+  }
+  return res;
+};
+// [START functions_start_instance_http]
+
+/**
+ * Parses the request body attributes of an HTTP request based on content-type.
+ *
+ * @param {!object} req a Cloud Functions HTTP request object.
+ * @returns {!object} an object with attributes matching the HTTP request body.
+ */
+function _parseReqBody (req) {
+  const contentType = req.get('content-type');
+  if (contentType === 'application/json') {
+    // Request.body automatically parsed as an object.
+    return req.body;
+  } else if (contentType === 'application/octet-stream') {
+    // Convert buffer to a string and parse as JSON string.
+    return JSON.parse(req.body.toString());
+  } else {
+    throw new Error('Unsupported HTTP content-type ' + req.get('content-type') +
+        '; use application/json or application/octet-stream');
+  }
+}
+
+/**
+ * Validates that a request body contains the expected fields.
+ *
+ * @param {!object} reqBody the request body to validate.
+ * @returns {!object} the request body object.
+ */
+function _validateReqBody (reqBody) {
+  if (!reqBody.zone) {
+    throw new Error(`Attribute 'zone' missing from POST request`);
+  } else if (!reqBody.instance) {
+    throw new Error(`Attribute 'instance' missing from POST request`);
+  }
+  return reqBody;
+}
+
+/**
+ * Validates that a HTTP request contains the expected fields.
+ *
+ * @param {!object} req the request to validate.
+ * @returns {!object} the request object.
+ */
+function _validateReq (req) {
+  if (req.method !== 'POST') {
+    throw new Error('Unsupported HTTP method ' + req.method +
+        '; use method POST');
+  } else if (typeof req.get('content-type') === 'undefined') {
+    throw new Error('HTTP content-type missing');
+  }
+  return req;
+}
+// [END functions_start_instance_http]
+// [END functions_stop_instance_http]

functions/scheduleinstance/package.json

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+{
+  "name": "schedule-instance",
+  "version": "0.0.1",
+  "private": true,
+  "license": "Apache-2.0",
+  "author": "Google Inc.",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/GoogleCloudPlatform/nodejs-docs-samples.git"
+  },
+  "engines": {
+    "node": ">=6.0"
+  },
+  "scripts": {
+    "lint": "repo-tools lint",
+    "pretest": "npm run lint",
+    "test": "ava -T 20s --verbose test/*.test.js"
+  },
+  "devDependencies": {
+    "@google-cloud/nodejs-repo-tools": "2.2.1",
+    "ava": "0.25.0",
+    "proxyquire": "2.0.0",
+    "sinon": "4.4.2"
+  },
+  "dependencies": {
+    "@google-cloud/compute": "^0.10.0",
+    "safe-buffer": "5.1.1"
+  }
+}