Adds monitored resource to [core]

packages/opencensus-core/package.json

@@ -40,7 +40,8 @@
   "devDependencies": {
     "@types/continuation-local-storage": "^3.2.1",
     "@types/mocha": "^2.2.48",
-    "@types/node": "^9.4.7",
+    "@types/nock": "^9.3.0",
+    "@types/node": "^9.6.35",
     "@types/once": "^1.4.0",
     "@types/semver": "^5.5.0",
     "@types/shimmer": "^1.0.1",
@@ -49,6 +50,7 @@
     "intercept-stdout": "^0.1.2",
     "mocha": "^5.0.4",
     "ncp": "^2.0.0",
+    "nock": "^10.0.1",
     "nyc": "11.6.0",
     "ts-node": "^4.0.0",
     "typescript": "~2.6.1"

packages/opencensus-core/src/common/monitored-resource/aws-identity-document-utils.ts

@@ -0,0 +1,100 @@
+/**
+ * Copyright 2018, OpenCensus Authors
+ *
+ * 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.
+ */
+
+import {get} from 'http';
+import * as logger from '../../common/console-logger';
+import * as loggerTypes from '../../common/types';
+
+/** Util methods for getting and parsing AWS instance identity document. */
+export class AwsIdentityDocumentUtils {
+  /** Aws instance identity URL */
+  static HOST = '169.254.169.254';
+  static readonly PATH = '/latest/dynamic/instance-identity/document';
+  static readonly PORT = 80;
+  static runned = false;
+  static metadata: Record<string, string> = {};
+  static promise: Promise<Record<string, string>>;
+  static readonly logger: loggerTypes.Logger = logger.logger();
+
+  /**
+   * Establishes an HTTP connection to AWS instance identity document url.
+   * If the application is running on an EC2 instance, we should be able
+   * to get back a valid JSON document. Parses that document and stores
+   * the identity properties in a local map.
+   */
+  static run() {
+    if (AwsIdentityDocumentUtils.runned) {
+      return AwsIdentityDocumentUtils.promise;
+    }
+    AwsIdentityDocumentUtils.promise =
+        AwsIdentityDocumentUtils.getDocument().then(metadata => {
+          if (Object.keys(metadata).length) {
+            AwsIdentityDocumentUtils.metadata = metadata;
+            AwsIdentityDocumentUtils.runned = true;
+          }
+          return metadata;
+        });
+    return AwsIdentityDocumentUtils.promise;
+  }
+
+  /**
+   * Fetches the requested instance metadata entry.
+   * @param name Attribute name relative to the computeMetadata/v1 prefix
+   */
+  private static getDocument() {
+    const promise = new Promise((resolve, reject) => {
+      get({
+        host: AwsIdentityDocumentUtils.HOST,
+        path: AwsIdentityDocumentUtils.PATH,
+        port: AwsIdentityDocumentUtils.PORT
+      },
+          (response) => {
+            let body = '';
+            response.on('data', chunk => body += chunk);
+            response.on('end', () => {
+              if (response.statusCode >= 200 && response.statusCode < 300) {
+                try {
+                  const data = JSON.parse(body);
+                  resolve(data);
+                } catch (e) {
+                  response.resume();
+                }
+              } else {
+                const errorMessage =
+                    `Request Failed. Status code: ${response.statusCode}`;
+                AwsIdentityDocumentUtils.logger.error(errorMessage);
+                reject(errorMessage);
+                response.resume();
+              }
+            });
+          });
+    });
+    return promise.catch(e => e);
+  }
+
+  /**
+   * AWS Instance Identity Document is a JSON file.
+   * See
+   * docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-identity-documents.html.
+   */
+  getMetadata() {
+    return AwsIdentityDocumentUtils.metadata;
+  }
+
+  static isRunning() {
+    return AwsIdentityDocumentUtils.runned;
+  }
+}