[identity] add support for app service 2019

sdk/identity/identity/CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Features Added
 
+- Added support for App Service 2019 resource in Managed Identity Credential.
+
 ### Breaking Changes
 
 ### Bugs Fixed

sdk/identity/identity/src/credentials/managedIdentityCredential/appServiceMsi2019.ts

@@ -0,0 +1,109 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+import {
+  createHttpHeaders,
+  createPipelineRequest,
+  PipelineRequestOptions,
+} from "@azure/core-rest-pipeline";
+import { AccessToken, GetTokenOptions } from "@azure/core-auth";
+import { TokenResponseParsedBody } from "../../client/identityClient";
+import { credentialLogger } from "../../util/logging";
+import { MSI, MSIConfiguration } from "./models";
+import { mapScopesToResource } from "./utils";
+
+const msiName = "ManagedIdentityCredential - AppServiceMSI 2019";
+const logger = credentialLogger(msiName);
+
+/**
+ * Formats the expiration date of the received token into the number of milliseconds between that date and midnight, January 1, 1970.
+ */
+function expiresOnParser(requestBody: TokenResponseParsedBody): number {
+  // App Service always returns string expires_on values.
+  return Date.parse(requestBody.expires_on! as string);
+}
+
+/**
+ * Generates the options used on the request for an access token.
+ */
+function prepareRequestOptions(
+  scopes: string | string[],
+  clientId?: string,
+  resourceId?: string
+): PipelineRequestOptions {
+  const resource = mapScopesToResource(scopes);
+  if (!resource) {
+    throw new Error(`${msiName}: Multiple scopes are not supported.`);
+  }
+
+  const queryParameters: Record<string, string> = {
+    resource,
+    "api-version": "2019-08-01",
+  };
+
+  if (clientId) {
+    queryParameters.client_id = clientId;
+  }
+
+  if (resourceId) {
+    queryParameters.mi_res_id = resourceId;
+  }
+  const query = new URLSearchParams(queryParameters);
+
+  // This error should not bubble up, since we verify that this environment variable is defined in the isAvailable() method defined below.
+  if (!process.env.IDENTITY_ENDPOINT) {
+    throw new Error(`${msiName}: Missing environment variable: IDENTITY_ENDPOINT`);
+  }
+  if (!process.env.IDENTITY_HEADER) {
+    throw new Error(`${msiName}: Missing environment variable: IDENTITY_HEADER`);
+  }
+
+  return {
+    url: `${process.env.IDENTITY_ENDPOINT}?${query.toString()}`,
+    method: "GET",
+    headers: createHttpHeaders({
+      Accept: "application/json",
+      "X-IDENTITY-HEADER": process.env.IDENTITY_HEADER,
+    }),
+  };
+}
+
+/**
+ * Defines how to determine whether the Azure App Service MSI is available, and also how to retrieve a token from the Azure App Service MSI.
+ */
+export const appServiceMsi2019: MSI = {
+  async isAvailable({ scopes }): Promise<boolean> {
+    const resource = mapScopesToResource(scopes);
+    if (!resource) {
+      logger.info(`${msiName}: Unavailable. Multiple scopes are not supported.`);
+      return false;
+    }
+    const env = process.env;
+    const result = Boolean(env.IDENTITY_ENDPOINT && env.IDENTITY_HEADER);
+    if (!result) {
+      logger.info(
+        `${msiName}: Unavailable. The environment variables needed are: IDENTITY_ENDPOINT and IDENTITY_HEADER.`
+      );
+    }
+    return result;
+  },
+  async getToken(
+    configuration: MSIConfiguration,
+    getTokenOptions: GetTokenOptions = {}
+  ): Promise<AccessToken | null> {
+    const { identityClient, scopes, clientId, resourceId } = configuration;
+
+    logger.info(
+      `${msiName}: Using the endpoint and the secret coming form the environment variables: IDENTITY_ENDPOINT=${process.env.IDENTITY_ENDPOINT} and IDENTITY_HEADER=[REDACTED].`
+    );
+
+    const request = createPipelineRequest({
+      abortSignal: getTokenOptions.abortSignal,
+      ...prepareRequestOptions(scopes, clientId, resourceId),
+      // Generally, MSI endpoints use the HTTP protocol, without transport layer security (TLS).
+      allowInsecureConnection: true,
+    });
+    const tokenResponse = await identityClient.sendTokenRequest(request, expiresOnParser);
+    return (tokenResponse && tokenResponse.accessToken) || null;
+  },
+};

sdk/identity/identity/src/credentials/managedIdentityCredential/index.ts

@@ -16,6 +16,7 @@ import { MSI } from "./models";
 import { arcMsi } from "./arcMsi";
 import { tokenExchangeMsi } from "./tokenExchangeMsi";
 import { fabricMsi } from "./fabricMsi";
+import { appServiceMsi2019 } from "./appServiceMsi2019";
 
 const logger = credentialLogger("ManagedIdentityCredential");
 
@@ -123,7 +124,15 @@ export class ManagedIdentityCredential implements TokenCredential {
       return this.cachedMSI;
     }
 
-    const MSIs = [fabricMsi, appServiceMsi2017, cloudShellMsi, arcMsi, tokenExchangeMsi(), imdsMsi];
+    const MSIs = [
+      fabricMsi,
+      appServiceMsi2019,
+      appServiceMsi2017,
+      cloudShellMsi,
+      arcMsi,
+      tokenExchangeMsi(),
+      imdsMsi,
+    ];
 
     for (const msi of MSIs) {
       if (

sdk/identity/identity/test/internal/node/managedIdentityCredential.spec.ts

@@ -507,6 +507,86 @@ describe("ManagedIdentityCredential", function () {
     }
   });
 
+  it("sends an authorization request correctly in an App Service 2019 environment by client id", async () => {
+    // Trigger App Service behavior by setting environment variables
+    process.env.IDENTITY_ENDPOINT = "https://endpoint";
+    process.env.IDENTITY_HEADER = "HEADER";
+
+    const authDetails = await testContext.sendCredentialRequests({
+      scopes: ["https://service/.default"],
+      credential: new ManagedIdentityCredential("client"),
+      secureResponses: [
+        createResponse(200, {
+          access_token: "token",
+          expires_on: "06/20/2021 02:57:58 +00:00",
+        }),
+      ],
+    });
+
+    const authRequest = authDetails.requests[0];
+    console.log(`authDetails = ${authDetails}`);
+    console.log(`authRequest = ${authRequest}`);
+    const query = new URLSearchParams(authRequest.url.split("?")[1]);
+
+    assert.equal(authRequest.method, "GET");
+    assert.equal(query.get("client_id"), "client");
+    assert.equal(decodeURIComponent(query.get("resource")!), "https://service");
+    assert.ok(
+      authRequest.url.startsWith(process.env.IDENTITY_ENDPOINT),
+      "URL does not start with expected host and path"
+    );
+    assert.equal(authRequest.headers["X-IDENTITY-HEADER"], process.env.IDENTITY_HEADER);
+    assert.ok(
+      authRequest.url.indexOf(`api-version=2019-08-01`) > -1,
+      "URL does not have expected version"
+    );
+    if (authDetails.result?.token) {
+      assert.equal(authDetails.result.expiresOnTimestamp, 1624157878000);
+    } else {
+      assert.fail("No token was returned!");
+    }
+  });
+
+  it("sends an authorization request correctly in an App Service 2019 environment by resource id", async () => {
+    // Trigger App Service behavior by setting environment variables
+    process.env.IDENTITY_ENDPOINT = "https://endpoint";
+    process.env.IDENTITY_HEADER = "HEADER";
+
+    const authDetails = await testContext.sendCredentialRequests({
+      scopes: ["https://service/.default"],
+      credential: new ManagedIdentityCredential({ resourceId: "RESOURCE-ID" }),
+      secureResponses: [
+        createResponse(200, {
+          access_token: "token",
+          expires_on: "06/20/2021 02:57:58 +00:00",
+        }),
+      ],
+    });
+
+    const authRequest = authDetails.requests[0];
+    console.log(`authDetails = ${authDetails}`);
+    console.log(`authRequest = ${authRequest}`);
+    const query = new URLSearchParams(authRequest.url.split("?")[1]);
+
+    assert.equal(authRequest.method, "GET");
+    assert.equal(decodeURIComponent(query.get("resource")!), "https://service");
+    assert.equal(decodeURIComponent(query.get("mi_res_id")!), "RESOURCE-ID");
+    assert.ok(
+      authRequest.url.startsWith(process.env.IDENTITY_ENDPOINT),
+      "URL does not start with expected host and path"
+    );
+    assert.equal(authRequest.headers["X-IDENTITY-HEADER"], process.env.IDENTITY_HEADER);
+    assert.ok(
+      authRequest.url.indexOf(`api-version=2019-08-01`) > -1,
+      "URL does not have expected version"
+    );
+    if (authDetails.result?.token) {
+      assert.equal(authDetails.result.expiresOnTimestamp, 1624157878000);
+    } else {
+      assert.fail("No token was returned!");
+    }
+  });
+
   it("sends an authorization request correctly in an Cloud Shell environment", async () => {
     // Trigger Cloud Shell behavior by setting environment variables
     process.env.MSI_ENDPOINT = "https://endpoint";