HADOOP-18610: [ABFS] OAuth2 Token Provider support for Azure Workload Identity

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/AbfsConfiguration.java

@@ -59,6 +59,7 @@
 import org.apache.hadoop.fs.azurebfs.oauth2.MsiTokenProvider;
 import org.apache.hadoop.fs.azurebfs.oauth2.RefreshTokenBasedTokenProvider;
 import org.apache.hadoop.fs.azurebfs.oauth2.UserPasswordTokenProvider;
+import org.apache.hadoop.fs.azurebfs.oauth2.WorkloadIdentityTokenProvider;
 import org.apache.hadoop.fs.azurebfs.security.AbfsDelegationTokenManager;
 import org.apache.hadoop.fs.azurebfs.services.AuthType;
 import org.apache.hadoop.fs.azurebfs.services.ExponentialRetryPolicy;
@@ -983,6 +984,20 @@ public AccessTokenProvider getTokenProvider() throws TokenAccessProviderExceptio
           tokenProvider = new RefreshTokenBasedTokenProvider(authEndpoint,
               clientId, refreshToken);
           LOG.trace("RefreshTokenBasedTokenProvider initialized");
+        } else if (tokenProviderClass == WorkloadIdentityTokenProvider.class) {
+          String authority = appendSlashIfNeeded(
+              getTrimmedPasswordString(FS_AZURE_ACCOUNT_OAUTH_MSI_AUTHORITY,
+              AuthConfigurations.DEFAULT_FS_AZURE_ACCOUNT_OAUTH_MSI_AUTHORITY));
+          String tenantGuid =
+              getMandatoryPasswordString(FS_AZURE_ACCOUNT_OAUTH_MSI_TENANT);
+          String clientId =
+              getMandatoryPasswordString(FS_AZURE_ACCOUNT_OAUTH_CLIENT_ID);
+          String tokenFile =
+              getTrimmedPasswordString(FS_AZURE_ACCOUNT_OAUTH_TOKEN_FILE,
+              AuthConfigurations.DEFAULT_FS_AZURE_ACCOUNT_OAUTH_TOKEN_FILE);
+          tokenProvider = new WorkloadIdentityTokenProvider(
+              authority, tenantGuid, clientId, tokenFile);
+          LOG.trace("WorkloadIdentityTokenProvider initialized");
         } else {
           throw new IllegalArgumentException("Failed to initialize " + tokenProviderClass);
         }

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/constants/AuthConfigurations.java

@@ -39,6 +39,10 @@ public final class AuthConfigurations {
   public static final String
       DEFAULT_FS_AZURE_ACCOUNT_OAUTH_REFRESH_TOKEN_ENDPOINT =
       "https://login.microsoftonline.com/Common/oauth2/token";
+  /** Default OAuth token file path for the workload identity flow. */
+  public static final String
+      DEFAULT_FS_AZURE_ACCOUNT_OAUTH_TOKEN_FILE =
+      "/var/run/secrets/azure/tokens/azure-identity-token";
 
   private AuthConfigurations() {
   }

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/constants/ConfigurationKeys.java

@@ -273,6 +273,8 @@ public final class ConfigurationKeys {
   public static final String FS_AZURE_ACCOUNT_OAUTH_REFRESH_TOKEN = "fs.azure.account.oauth2.refresh.token";
   /** Key for oauth AAD refresh token endpoint: {@value}. */
   public static final String FS_AZURE_ACCOUNT_OAUTH_REFRESH_TOKEN_ENDPOINT = "fs.azure.account.oauth2.refresh.token.endpoint";
+  /** Key for oauth AAD workload identity token file path: {@value}. */
+  public static final String FS_AZURE_ACCOUNT_OAUTH_TOKEN_FILE = "fs.azure.account.oauth2.token.file";
   /** Key for enabling the tracking of ABFS API latency and sending the latency numbers to the ABFS API service */
   public static final String FS_AZURE_ABFS_LATENCY_TRACK = "fs.azure.abfs.latency.track";
 

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/oauth2/AzureADAuthenticator.java

@@ -57,6 +57,9 @@ public final class AzureADAuthenticator {
   private static final Logger LOG = LoggerFactory.getLogger(AzureADAuthenticator.class);
   private static final String RESOURCE_NAME = "https://storage.azure.com/";
   private static final String SCOPE = "https://storage.azure.com/.default";
+  private static final String JWT_BEARER_ASSERTION = "urn:ietf:params:oauth:client-assertion-type:jwt-bearer";
+  private static final String CLIENT_CREDENTIALS = "client_credentials";
+  private static final String OAUTH_VERSION_2_0 = "/oauth2/v2.0/";
   private static final int CONNECT_TIMEOUT = 30 * 1000;
   private static final int READ_TIMEOUT = 30 * 1000;
 
@@ -95,22 +98,61 @@ public static AzureADToken getTokenUsingClientCreds(String authEndpoint,
     Preconditions.checkNotNull(authEndpoint, "authEndpoint");
     Preconditions.checkNotNull(clientId, "clientId");
     Preconditions.checkNotNull(clientSecret, "clientSecret");
-    boolean isVersion2AuthenticationEndpoint = authEndpoint.contains("/oauth2/v2.0/");
 
     QueryParams qp = new QueryParams();
-    if (isVersion2AuthenticationEndpoint) {
+    if (isVersion2AuthenticationEndpoint(authEndpoint)) {
       qp.add("scope", SCOPE);
     } else {
       qp.add("resource", RESOURCE_NAME);
     }
-    qp.add("grant_type", "client_credentials");
+    qp.add("grant_type", CLIENT_CREDENTIALS);
     qp.add("client_id", clientId);
     qp.add("client_secret", clientSecret);
     LOG.debug("AADToken: starting to fetch token using client creds for client ID " + clientId);
 
     return getTokenCall(authEndpoint, qp.serialize(), null, null);
   }
 
+  /**
+   * Gets Azure Active Directory token using the user ID and a JWT assertion
+   * generated by a federated authentication process.
+   *
+   * The federation process uses a feature from Azure Active Directory
+   * called workload identity. A workload identity is an identity used
+   * by a software workload (such as an application, service, script,
+   * or container) to authenticate and access other services and resources.
+   *
+   *
+   * @param authEndpoint the OAuth 2.0 token endpoint associated
+   *                     with the user's directory (obtain from
+   *                     Active Directory configuration)
+   * @param clientId     the client ID (GUID) of the client web app
+   *                     obtained from Azure Active Directory configuration
+   * @param clientAssertion the JWT assertion token
+   * @return {@link AzureADToken} obtained using the creds
+   * @throws IOException throws IOException if there is a failure in connecting to Azure AD
+   */
+  public static AzureADToken getTokenUsingJWTAssertion(String authEndpoint,
+      String clientId, String clientAssertion) throws IOException {
+    Preconditions.checkNotNull(authEndpoint, "authEndpoint");
+    Preconditions.checkNotNull(clientId, "clientId");
+    Preconditions.checkNotNull(clientAssertion, "clientAssertion");
+
+    QueryParams qp = new QueryParams();
+    if (isVersion2AuthenticationEndpoint(authEndpoint)) {
+      qp.add("scope", SCOPE);
+    } else {
+      qp.add("resource", RESOURCE_NAME);
+    }
+    qp.add("grant_type", CLIENT_CREDENTIALS);
+    qp.add("client_id", clientId);
+    qp.add("client_assertion", clientAssertion);
+    qp.add("client_assertion_type", JWT_BEARER_ASSERTION);
+    LOG.debug("AADToken: starting to fetch token using client assertion for client ID " + clientId);
+
+    return getTokenCall(authEndpoint, qp.serialize(), null, "POST");
+  }
+
   /**
    * Gets AAD token from the local virtual machine's VM extension. This only works on
    * an Azure VM with MSI extension
@@ -523,4 +565,8 @@ private static String consumeInputStream(InputStream inStream, int length) throw
 
     return new String(b, 0, totalBytesRead, StandardCharsets.UTF_8);
   }
+
+  private static boolean isVersion2AuthenticationEndpoint(String authEndpoint) {
+    return authEndpoint.contains(OAUTH_VERSION_2_0);
+  }
 }

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/oauth2/WorkloadIdentityTokenProvider.java

@@ -0,0 +1,142 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+package org.apache.hadoop.fs.azurebfs.oauth2;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.apache.commons.io.FileUtils;
+import org.apache.hadoop.classification.VisibleForTesting;
+import org.apache.hadoop.thirdparty.com.google.common.base.Strings;
+import org.apache.hadoop.util.Preconditions;
+
+/**
+ * Provides tokens based on Azure AD Workload Identity.
+ */
+public class WorkloadIdentityTokenProvider extends AccessTokenProvider {
+
+  private static final String OAUTH2_TOKEN_PATH = "/oauth2/v2.0/token";
+  private static final Logger LOG = LoggerFactory.getLogger(AccessTokenProvider.class);
+  private static final String EMPTY_TOKEN_FILE_ERROR = "Empty token file found at specified path: ";
+  private static final String TOKEN_FILE_READ_ERROR = "Error reading token file at specified path: ";
+
+  private final String authEndpoint;
+  private final String clientId;
+  private final String tokenFile;
+  private long tokenFetchTime = -1;
+
+  public WorkloadIdentityTokenProvider(final String authority, final String tenantId,
+      final String clientId, final String tokenFile) {
+    Preconditions.checkNotNull(authority, "authority");
+    Preconditions.checkNotNull(tenantId, "tenantId");
+    Preconditions.checkNotNull(clientId, "clientId");
+    Preconditions.checkNotNull(tokenFile, "tokenFile");
+
+    this.authEndpoint = authority + tenantId + OAUTH2_TOKEN_PATH;
+    this.clientId = clientId;
+    this.tokenFile = tokenFile;
+  }
+
+  @Override
+  protected AzureADToken refreshToken() throws IOException {
+    LOG.debug("AADToken: refreshing token from JWT Assertion");
+    String clientAssertion = getClientAssertion();
+    AzureADToken token = getTokenUsingJWTAssertion(clientAssertion);
+    tokenFetchTime = System.currentTimeMillis();
+    return token;
+  }
+
+  /**
+   * Checks if the token is about to expire as per base expiry logic.
+   * Otherwise, expire if there is a clock skew issue in the system.
+   *
+   * @return true if the token is expiring in next 1 hour or if a token has
+   * never been fetched
+   */
+  @Override
+  protected boolean isTokenAboutToExpire() {
+    if (tokenFetchTime == -1 || super.isTokenAboutToExpire()) {
+      return true;
+    }
+
+    // In case of, any clock skew issues, refresh token.
+    long elapsedTimeSinceLastTokenRefreshInMillis =
+        System.currentTimeMillis() - tokenFetchTime;
+    boolean expiring = elapsedTimeSinceLastTokenRefreshInMillis < 0;
+    if (expiring) {
+      // Clock Skew issue. Refresh token.
+      LOG.debug("JWTToken: token renewing. Time elapsed since last token fetch:"
+          + " {} milliseconds", elapsedTimeSinceLastTokenRefreshInMillis);
+    }
+
+    return expiring;
+  }
+
+  /**
+   * Gets the client assertion from the token file.
+   * The token file should contain the client assertion in JWT format.
+   * It should be a String containing Base64Url encoded JSON Web Token (JWT).
+   * See <a href="https://azure.github.io/azure-workload-identity/docs/faq.html#does-workload-identity-work-in-disconnected-environments">
+   * Azure Workload Identity FAQ</a>.
+   *
+   * @return the client assertion.
+   * @throws IOException if the token file is empty.
+   */
+  private String getClientAssertion()
+      throws IOException {
+    String clientAssertion = "";
+    try {
+      File file = new File(tokenFile);
+      clientAssertion = FileUtils.readFileToString(file, "UTF-8");
+    } catch (Exception e) {
+      throw new IOException(TOKEN_FILE_READ_ERROR + tokenFile, e);
+    }
+    if (Strings.isNullOrEmpty(clientAssertion)) {
+      throw new IOException(EMPTY_TOKEN_FILE_ERROR + tokenFile);
+    }
+    return clientAssertion;
+  }
+
+  /**
+   * Gets the Azure AD token from a client assertion in JWT format.
+   * This method exists to make unit testing possible.
+   *
+   * @param clientAssertion the client assertion.
+   * @return the Azure AD token.
+   * @throws IOException if there is a failure in connecting to Azure AD.
+   */
+  @VisibleForTesting
+  AzureADToken getTokenUsingJWTAssertion(String clientAssertion) throws IOException {
+    return AzureADAuthenticator
+        .getTokenUsingJWTAssertion(authEndpoint, clientId, clientAssertion);
+  }
+
+  /**
+   * Returns the last time the token was fetched from the token file.
+   * This method exists to make unit testing possible.
+   *
+   * @return the time the token was last fetched.
+   */
+  @VisibleForTesting
+  long getTokenFetchTime() {
+    return tokenFetchTime;
+  }
+}

hadoop-tools/hadoop-azure/src/site/markdown/abfs.md

@@ -321,10 +321,9 @@ What can be changed is what secrets/credentials are used to authenticate the cal
 
 The authentication mechanism is set in `fs.azure.account.auth.type` (or the
 account specific variant). The possible values are SharedKey, OAuth, Custom
-and SAS. For the various OAuth options use the config `fs.azure.account
-.oauth.provider.type`. Following are the implementations supported
-ClientCredsTokenProvider, UserPasswordTokenProvider, MsiTokenProvider and
-RefreshTokenBasedTokenProvider. An IllegalArgumentException is thrown if
+and SAS. For the various OAuth options use the config `fs.azure.account.oauth.provider.type`. Following are the implementations supported
+ClientCredsTokenProvider, UserPasswordTokenProvider, MsiTokenProvider,
+RefreshTokenBasedTokenProvider and WorkloadIdentityTokenProvider. An IllegalArgumentException is thrown if
 the specified provider type is not one of the supported.
 
 All secrets can be stored in JCEKS files. These are encrypted and password
@@ -561,6 +560,54 @@ The Azure Portal/CLI is used to create the service identity.
 </property>
 ```
 
+### <a name="workload-identity"></a> Azure Workload Identity
+
+[Azure Workload Identities](https://docs.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/overview), formerly "Azure AD pod identity".
+
+OAuth 2.0 tokens are written to a file that is only accessible
+from the executing pod (`/var/run/secrets/azure/tokens/azure-identity-token`).
+The issued credentials can be used to authenticate.
+
+The Azure Portal/CLI is used to create the service identity.
+
+```xml
+<property>
+  <name>fs.azure.account.auth.type</name>
+  <value>OAuth</value>
+  <description>
+  Use OAuth authentication
+  </description>
+</property>
+<property>
+  <name>fs.azure.account.oauth.provider.type</name>
+  <value>org.apache.hadoop.fs.azurebfs.oauth2.WorkloadIdentityTokenProvider</value>
+  <description>
+  Use Workload Identity for issuing OAuth tokens
+  </description>
+</property>
+<property>
+  <name>fs.azure.account.oauth2.msi.tenant</name>
+  <value>${env.AZURE_TENANT_ID}</value>
+  <description>
+  Optional MSI Tenant ID
+  </description>
+</property>
+<property>
+  <name>fs.azure.account.oauth2.client.id</name>
+  <value>${env.AZURE_CLIENT_ID}</value>
+  <description>
+  Optional Client ID
+  </description>
+</property>
+<property>
+  <name>fs.azure.account.oauth2.token.file</name>
+  <value>${env.AZURE_FEDERATED_TOKEN_FILE}</value>
+  <description>
+  Token file path
+  </description>
+</property>
+```
+
 ### Custom OAuth 2.0 Token Provider
 
 A Custom OAuth 2.0 token provider supplies the ABFS connector with an OAuth 2.0

hadoop-tools/hadoop-azure/src/site/markdown/testing_azure.md

@@ -879,6 +879,42 @@ hierarchical namespace enabled, and set the following configuration settings:
    </property>
   -->
 
+  <!--2.5. If "WorkloadIdentityTokenProvider" is set as key provider, uncomment below and
+           set tenant, client id and token file path.
+
+           All service principals must have federated identity credentials for Kubernetes.
+           See Azure docs: https://learn.microsoft.com/en-us/azure/active-directory/workload-identities/workload-identity-federation-create-trust?pivots=identity-wif-apps-methods-azp#kubernetes
+
+           Retrieve the Azure identity token from kubernetes:
+           1. Create AKS cluster with Workload Identity: https://learn.microsoft.com/en-us/azure/aks/workload-identity-deploy-cluster
+           2. Create the pod:
+              kubectl apply -f src/test/resources/workload-identity-pod.yaml
+           3. After the pod is running, retrieve the identity token from the pod logs:
+              kubectl logs pod/workload-identity
+           4. Save the identity token to the token file path specified below.
+
+           The Azure identity token expires after 1 hour.
+  -->
+  <!--
+   <property>
+     <name>fs.azure.account.oauth2.msi.tenant.{ABFS_ACCOUNT_NAME}</name>
+     <value>{tenantGuid}</value>
+     <description>msi tenantGuid.</description>
+   </property>
+
+   <property>
+     <name>fs.azure.account.oauth2.client.id.{ABFS_ACCOUNT_NAME}</name>
+     <value>{client id}</value>
+     <description>AAD client id.</description>
+   </property>
+
+   <property>
+     <name>fs.azure.account.oauth2.client.token.file.{ABFS_ACCOUNT_NAME}</name>
+     <value>{token file path}</value>
+     <description>Azure identity token file path.</description>
+   </property>
+  -->
+
   <!--
     <property>
         <name>fs.azure.identity.transformer.enable.short.name</name>