agents-cred/src/main/java/org/apache/ranger/authorization/hadoop/utils/RangerCredentialProvider.java

/*
 * 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.ranger.authorization.hadoop.utils;

import java.util.List;

import org.apache.hadoop.security.alias.CredentialProvider;
import org.apache.hadoop.security.alias.CredentialProviderFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;


public final class RangerCredentialProvider {

	private static final Log LOG = LogFactory.getLog(RangerCredentialProvider.class);

	private static final RangerCredentialProvider CRED_PROVIDER = new RangerCredentialProvider();

	protected RangerCredentialProvider() {
		//
	}

	public static RangerCredentialProvider getInstance() {
		return CRED_PROVIDER;
	}

	public char[] getCredentialString(String url, String alias) {
		List<CredentialProvider> providers = getCredentialProviders(url);

		if (providers != null) {
			for (CredentialProvider provider : providers) {
				try {
					CredentialProvider.CredentialEntry credEntry = provider.getCredentialEntry(alias);

					if (credEntry != null) {
						return credEntry.getCredential();
					}
				} catch(Exception ie) {
					LOG.error("Unable to get the Credential Provider from the Configuration", ie);	
				}
			}
		}
		return null;
	}

	List<CredentialProvider> getCredentialProviders(String url) {
		try {
			Configuration conf = new Configuration();

			conf.set(CredentialProviderFactory.CREDENTIAL_PROVIDER_PATH, url);

			return CredentialProviderFactory.getProviders(conf);
		} catch(Exception ie) {
			LOG.error("Unable to get the Credential Provider from the Configuration", ie);
		}
		return null;
	}

}