com.amazonaws.auth.AWSCredentialsProviderChain Maven / Gradle / Ivy
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/*
* Copyright 2012-2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 com.amazonaws.auth;
import com.amazonaws.AmazonClientException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import java.util.LinkedList;
import java.util.List;
/**
* {@link AWSCredentialsProvider} implementation that chains together multiple
* credentials providers. When a caller first requests credentials from this
* provider, it calls all the providers in the chain, in the original order
* specified, until one can provide credentials, and then returns those
* credentials. If all of the credential providers in the chain have been
* called, and none of them can provide credentials, then this class will throw
* an exception indicated that no credentials are available.
*
* By default, this class will remember the first credentials provider in the
* chain that was able to provide credentials, and will continue to use that
* provider when credentials are requested in the future, instead of traversing
* the chain each time. This behavior can be controlled through the
* {@link #setReuseLastProvider(boolean)} method.
*/
public class AWSCredentialsProviderChain implements AWSCredentialsProvider {
private static final Log log = LogFactory.getLog(AWSCredentialsProviderChain.class);
private List credentialsProviders =
new LinkedList();
private boolean reuseLastProvider = true;
private AWSCredentialsProvider lastUsedProvider;
/**
* Constructs a new AWSCredentialsProviderChain with the specified
* credential providers. When credentials are requested from this provider,
* it will call each of these credential providers in the same order
* specified here until one of them returns AWS security credentials.
*
* @param credentialsProviders The chain of credentials providers.
*/
public AWSCredentialsProviderChain(AWSCredentialsProvider... credentialsProviders) {
if (credentialsProviders == null || credentialsProviders.length == 0)
throw new IllegalArgumentException("No credential providers specified");
for (AWSCredentialsProvider provider : credentialsProviders) {
this.credentialsProviders.add(provider);
}
}
/**
* Returns true if this chain will reuse the last successful credentials
* provider for future credentials requests, otherwise, false if it will
* search through the chain each time.
*
* @return True if this chain will reuse the last successful credentials
* provider for future credentials requests.
*/
public boolean getReuseLastProvider() {
return reuseLastProvider;
}
/**
* Enables or disables caching of the last successful credentials provider
* in this chain. Reusing the last successful credentials provider will
* typically return credentials faster than searching through the chain.
*
* @param b Whether to enable or disable reusing the last successful
* credentials provider for future credentials requests instead
* of searching through the whole chain.
*/
public void setReuseLastProvider(boolean b) {
this.reuseLastProvider = b;
}
@Override
public AWSCredentials getCredentials() {
if (reuseLastProvider && lastUsedProvider != null) {
return lastUsedProvider.getCredentials();
}
for (AWSCredentialsProvider provider : credentialsProviders) {
try {
AWSCredentials credentials = provider.getCredentials();
if (credentials.getAWSAccessKeyId() != null &&
credentials.getAWSSecretKey() != null) {
log.debug("Loading credentials from " + provider.toString());
lastUsedProvider = provider;
return credentials;
}
} catch (Exception e) {
// Ignore any exceptions and move onto the next provider
log.debug("Unable to load credentials from " + provider.toString() +
": " + e.getMessage());
}
}
throw new AmazonClientException(
"Unable to load AWS credentials from any provider in the chain");
}
@Override
public void refresh() {
for (AWSCredentialsProvider provider : credentialsProviders) {
provider.refresh();
}
}
}