Add Metadata server sample. (GoogleCloudPlatform#485)

Author: jmdobry

appengine/metadata/package.json

@@ -0,0 +1,41 @@
+{
+  "name": "appengine-metadata",
+  "description": "Sample for accessing the Compute metadata server on GAE.",
+  "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": ">=4"
+  },
+  "scripts": {
+    "lint": "samples lint",
+    "pretest": "npm run lint",
+    "system-test": "samples test app",
+    "test": "npm run system-test",
+    "e2e-test": "samples test deploy"
+  },
+  "dependencies": {
+    "express": "4.15.4",
+    "got": "7.1.0"
+  },
+  "devDependencies": {
+    "@google-cloud/nodejs-repo-tools": "1.4.17"
+  },
+  "cloud-repo-tools": {
+    "test": {
+      "app": {
+        "msg": "External IP:",
+        "args": [
+          "server.js"
+        ]
+      }
+    },
+    "requiresKeyFile": false,
+    "requiresProjectId": false
+  }
+}

appengine/metadata/server.js

@@ -0,0 +1,60 @@
+/**
+ * Copyright 2017, 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.
+ */
+
+'use strict';
+
+// [START appengine_metadata]
+const express = require('express');
+const request = require('got');
+
+const app = express();
+app.enable('trust proxy');
+
+const METADATA_NETWORK_INTERFACE_URL = 'http://metadata/computeMetadata/v1/' +
+'/instance/network-interfaces/0/access-configs/0/external-ip';
+
+function getExternalIp () {
+  const options = {
+    headers: {
+      'Metadata-Flavor': 'Google'
+    },
+    json: true
+  };
+
+  return request(METADATA_NETWORK_INTERFACE_URL, options)
+    .then((response) => response.body)
+    .catch((err) => {
+      if (err || err.statusCode !== 200) {
+        console.log('Error while talking to metadata server, assuming localhost');
+        return 'localhost';
+      }
+      return Promise.reject(err);
+    });
+}
+
+app.get('/', (req, res, next) => {
+  getExternalIp()
+    .then((externalIp) => {
+      res.status(200).send(`External IP: ${externalIp}`).end();
+    })
+    .catch(next);
+});
+
+const PORT = process.env.PORT || 8080;
+app.listen(PORT, () => {
+  console.log(`App listening on port ${PORT}`);
+  console.log('Press Ctrl+C to quit.');
+});
+// [END appengine_metadata]

circle.yml

@@ -82,6 +82,7 @@ deployment:
       - node scripts/build "appengine/errorreporting"
       - node scripts/build "appengine/hello-world"
       - node scripts/build "appengine/mailjet"
+      - node scripts/build "appengine/metadata"
       - node scripts/build "appengine/static-files"
       - GCLOUD_STORAGE_BUCKET=docs-samples-gae-test-$(uuid); node scripts/build "appengine/storage"
       - node scripts/build "auth"