HADOOP-12723 S3A: Add ability to plug in any AWSCredentialsProvider. Contributed by Steven Wong.

hadoop-common-project/hadoop-common/src/main/resources/core-default.xml

@@ -757,12 +757,17 @@
 
 <property>
   <name>fs.s3a.access.key</name>
-  <description>AWS access key ID used by S3A file system. Omit for Role-based authentication.</description>
+  <description>AWS access key ID used by S3A file system. Omit for IAM role-based or provider-based authentication.</description>
 </property>
 
 <property>
   <name>fs.s3a.secret.key</name>
-  <description>AWS secret key used by S3A file system. Omit for Role-based authentication.</description>
+  <description>AWS secret key used by S3A file system. Omit for IAM role-based or provider-based authentication.</description>
+</property>
+
+<property>
+  <name>fs.s3a.aws.credentials.provider</name>
+  <description>Class name of a credentials provider that implements com.amazonaws.auth.AWSCredentialsProvider. Omit if using access/secret keys or another authentication mechanism.</description>
 </property>
 
 <property>

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/Constants.java

@@ -37,6 +37,10 @@ private Constants() {
   // s3 secret key
   public static final String SECRET_KEY = "fs.s3a.secret.key";
 
+  // aws credentials provider
+  public static final String AWS_CREDENTIALS_PROVIDER =
+      "fs.s3a.aws.credentials.provider";
+
   // number of simultaneous connections to s3
   public static final String MAXIMUM_CONNECTIONS = "fs.s3a.connection.maximum";
   public static final int DEFAULT_MAXIMUM_CONNECTIONS = 15;

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java

@@ -35,8 +35,8 @@
 import com.amazonaws.AmazonServiceException;
 import com.amazonaws.ClientConfiguration;
 import com.amazonaws.Protocol;
+import com.amazonaws.auth.AWSCredentialsProvider;
 import com.amazonaws.auth.AWSCredentialsProviderChain;
-
 import com.amazonaws.auth.InstanceProfileCredentialsProvider;
 import com.amazonaws.services.s3.AmazonS3Client;
 import com.amazonaws.services.s3.S3ClientOptions;
@@ -55,11 +55,10 @@
 import com.amazonaws.services.s3.transfer.Upload;
 import com.amazonaws.event.ProgressListener;
 import com.amazonaws.event.ProgressEvent;
-
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
-import org.apache.commons.lang.StringUtils;
 
+import org.apache.commons.lang.StringUtils;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.conf.Configuration;
@@ -133,17 +132,10 @@ public void initialize(URI name, Configuration conf) throws IOException {
     workingDir = new Path("/user", System.getProperty("user.name"))
         .makeQualified(this.uri, this.getWorkingDirectory());
 
-    AWSAccessKeys creds = getAWSAccessKeys(name, conf);
-
-    AWSCredentialsProviderChain credentials = new AWSCredentialsProviderChain(
-        new BasicAWSCredentialsProvider(
-            creds.getAccessKey(), creds.getAccessSecret()),
-        new InstanceProfileCredentialsProvider(),
-        new AnonymousAWSCredentialsProvider()
-    );
-
     bucket = name.getHost();
 
+    AWSCredentialsProvider credentials = getAWSCredentialsProvider(name, conf);
+
     ClientConfiguration awsConf = new ClientConfiguration();
     awsConf.setMaxConnections(intOption(conf, MAXIMUM_CONNECTIONS,
         DEFAULT_MAXIMUM_CONNECTIONS, 1));
@@ -280,7 +272,7 @@ private void initUserAgent(Configuration conf, ClientConfiguration awsConf) {
   }
 
   private void initAmazonS3Client(Configuration conf,
-      AWSCredentialsProviderChain credentials, ClientConfiguration awsConf)
+      AWSCredentialsProvider credentials, ClientConfiguration awsConf)
       throws IllegalArgumentException {
     s3 = new AmazonS3Client(credentials, awsConf);
     String endPoint = conf.getTrimmed(ENDPOINT, "");
@@ -395,6 +387,48 @@ AWSAccessKeys getAWSAccessKeys(URI name, Configuration conf)
     return new AWSAccessKeys(accessKey, secretKey);
   }
 
+  /**
+   * Create the standard credential provider, or load in one explicitly
+   * identified in the configuration.
+   * @param binding the S3 binding/bucket.
+   * @param conf configuration
+   * @return a credential provider
+   * @throws IOException on any problem. Class construction issues may be
+   * nested inside the IOE.
+   */
+  private AWSCredentialsProvider getAWSCredentialsProvider(URI binding,
+      Configuration conf) throws IOException {
+    AWSCredentialsProvider credentials;
+
+    String className = conf.getTrimmed(AWS_CREDENTIALS_PROVIDER);
+    if (StringUtils.isEmpty(className)) {
+      AWSAccessKeys creds = getAWSAccessKeys(binding, conf);
+      credentials = new AWSCredentialsProviderChain(
+          new BasicAWSCredentialsProvider(
+              creds.getAccessKey(), creds.getAccessSecret()),
+          new InstanceProfileCredentialsProvider(),
+          new AnonymousAWSCredentialsProvider()
+      );
+
+    } else {
+      try {
+        LOG.debug("Credential provider class is {}", className);
+        credentials = (AWSCredentialsProvider) Class.forName(className)
+            .getDeclaredConstructor(URI.class, Configuration.class)
+            .newInstance(this.uri, conf);
+      } catch (ClassNotFoundException e) {
+        throw new IOException(className + " not found.", e);
+      } catch (NoSuchMethodException | SecurityException e) {
+        throw new IOException(className + " constructor exception.", e);
+      } catch (ReflectiveOperationException | IllegalArgumentException e) {
+        throw new IOException(className + " instantiation exception.", e);
+      }
+      LOG.debug("Using {} for {}.", credentials, this.uri);
+    }
+
+    return credentials;
+  }
+
   /**
    * Return the protocol scheme for the FileSystem.
    *
@@ -1392,7 +1426,7 @@ public String toString() {
           .append('\'');
     }
     sb.append(", statistics {")
-        .append(statistics.toString())
+        .append(statistics)
         .append("}");
     sb.append(", metrics {")
         .append(instrumentation.dump("{", "=", "} ", true))

hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/index.md

@@ -177,20 +177,27 @@ If you do any of these: change your credentials immediately!
 
     <property>
       <name>fs.s3a.access.key</name>
-      <description>AWS access key ID. Omit for Role-based authentication.</description>
+      <description>AWS access key ID. Omit for IAM role-based or provider-based authentication.</description>
     </property>
 
     <property>
       <name>fs.s3a.secret.key</name>
-      <description>AWS secret key. Omit for Role-based authentication.</description>
+      <description>AWS secret key. Omit for IAM role-based or provider-based authentication.</description>
+    </property>
+
+    <property>
+      <name>fs.s3a.aws.credentials.provider</name>
+      <description>Class name of a credentials provider that implements com.amazonaws.auth.AWSCredentialsProvider.
+      Omit if using access/secret keys or another authentication mechanism.</description>
     </property>
 
 #### Protecting the AWS Credentials in S3A
 
-To protect these credentials from prying eyes, it is recommended that you use
+To protect the access/secret keys from prying eyes, it is recommended that you
+use either IAM role-based authentication (such as EC2 instance profile) or
 the credential provider framework securely storing them and accessing them
- through configuration. The following describes its use for AWS credentials
+through configuration. The following describes using the latter for AWS
-in S3A FileSystem.
+credentials in S3AFileSystem.
 
 For additional reading on the credential provider API see:
 [Credential Provider API](../../../hadoop-project-dist/hadoop-common/CredentialProviderAPI.html).
@@ -560,13 +567,13 @@ Example:
 
       <property>
         <name>fs.s3a.access.key</name>
-        <description>AWS access key ID. Omit for Role-based authentication.</description>
+        <description>AWS access key ID. Omit for IAM role-based authentication.</description>
         <value>DONOTCOMMITTHISKEYTOSCM</value>
       </property>
   
       <property>
         <name>fs.s3a.secret.key</name>
-        <description>AWS secret key. Omit for Role-based authentication.</description>
+        <description>AWS secret key. Omit for IAM role-based authentication.</description>
         <value>DONOTEVERSHARETHISSECRETKEY!</value>
       </property>
     </configuration>

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/TestS3AAWSCredentialsProvider.java

@@ -0,0 +1,106 @@
+/**
+ * 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.s3a;
+
+import static org.apache.hadoop.fs.s3a.Constants.*;
+import static org.junit.Assert.*;
+
+import java.io.IOException;
+import java.net.URI;
+
+import org.apache.hadoop.conf.Configuration;
+import org.junit.Test;
+
+import com.amazonaws.auth.AWSCredentials;
+import com.amazonaws.auth.AWSCredentialsProvider;
+import com.amazonaws.auth.AWSCredentialsProviderChain;
+import com.amazonaws.auth.BasicAWSCredentials;
+import com.amazonaws.auth.InstanceProfileCredentialsProvider;
+import com.amazonaws.services.s3.model.AmazonS3Exception;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Tests for {@link Constants#AWS_CREDENTIALS_PROVIDER} logic.
+ *
+ */
+public class TestS3AAWSCredentialsProvider {
+  private static final Logger LOG =
+      LoggerFactory.getLogger(TestS3AAWSCredentialsProvider.class);
+
+  @Test
+  public void testBadConfiguration() throws IOException {
+    Configuration conf = new Configuration();
+    conf.set(AWS_CREDENTIALS_PROVIDER, "no.such.class");
+    try {
+      S3ATestUtils.createTestFileSystem(conf);
+    } catch (IOException e) {
+      if (!(e.getCause() instanceof ClassNotFoundException)) {
+        LOG.error("Unexpected nested cause: {} in {}", e.getCause(), e, e);
+        throw e;
+      }
+    }
+  }
+
+  static class BadCredentialsProvider implements AWSCredentialsProvider {
+
+    @SuppressWarnings("unused")
+    public BadCredentialsProvider(URI name, Configuration conf) {
+    }
+
+    @Override
+    public AWSCredentials getCredentials() {
+      return new BasicAWSCredentials("bad_key", "bad_secret");
+    }
+
+    @Override
+    public void refresh() {
+    }
+  }
+
+  @Test
+  public void testBadCredentials() throws Exception {
+    Configuration conf = new Configuration();
+    conf.set(AWS_CREDENTIALS_PROVIDER, BadCredentialsProvider.class.getName());
+    try {
+      S3ATestUtils.createTestFileSystem(conf);
+    } catch (AmazonS3Exception e) {
+      if (e.getStatusCode() != 403) {
+        LOG.error("Unexpected status code: {}", e.getStatusCode(), e);
+        throw e;
+      }
+    }
+  }
+
+  static class GoodCredentialsProvider extends AWSCredentialsProviderChain {
+
+    @SuppressWarnings("unused")
+    public GoodCredentialsProvider(URI name, Configuration conf) {
+      super(new BasicAWSCredentialsProvider(conf.get(ACCESS_KEY),
+          conf.get(SECRET_KEY)), new InstanceProfileCredentialsProvider());
+    }
+  }
+
+  @Test
+  public void testGoodProvider() throws Exception {
+    Configuration conf = new Configuration();
+    conf.set(AWS_CREDENTIALS_PROVIDER, GoodCredentialsProvider.class.getName());
+    S3ATestUtils.createTestFileSystem(conf);
+  }
+}