/*
* Copyright 2011-2013 Amazon Technologies, Inc.
*
* Licensed 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://aws.amazon.com/apache2.0
*
* 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 java.util.Date;
import com.amazonaws.ClientConfiguration;
import com.amazonaws.services.securitytoken.AWSSecurityTokenService;
import com.amazonaws.services.securitytoken.AWSSecurityTokenServiceClient;
import com.amazonaws.services.securitytoken.model.AssumeRoleRequest;
import com.amazonaws.services.securitytoken.model.AssumeRoleResult;
import com.amazonaws.services.securitytoken.model.Credentials;
/**
* AWSCredentialsProvider implementation that uses the AWS Security Token
* Service to assume a Role and create temporary, short-lived sessions to use
* for authentication.
*/
public class STSAssumeRoleSessionCredentialsProvider implements AWSCredentialsProvider {
/** Default duration for started sessions. */
public static final int DEFAULT_DURATION_SECONDS = 900;
/** Time before expiry within which credentials will be renewed. */
private static final int EXPIRY_TIME_MILLIS = 60 * 1000;
/** The client for starting STS sessions. */
private final AWSSecurityTokenService securityTokenService;
/** The current session credentials. */
private AWSSessionCredentials sessionCredentials;
/** The expiration time for the current session credentials. */
private Date sessionCredentialsExpiration;
/** The arn of the role to be assumed. */
private String roleArn;
/** An identifier for the assumed role session. */
private String roleSessionName;
/**
* Constructs a new STSAssumeRoleSessionCredentialsProvider, which makes a
* request to the AWS Security Token Service (STS), uses the provided
* {@link #roleArn} to assume a role and then request short lived session
* credentials, which will then be returned by this class's
* {@link #getCredentials()} method.
*
* @param roleArn
* The ARN of the Role to be assumed.
* @param roleSessionName
* An identifier for the assumed role session.
*/
public STSAssumeRoleSessionCredentialsProvider(String roleArn, String roleSessionName) {
this.roleArn = roleArn;
this.roleSessionName = roleSessionName;
securityTokenService = new AWSSecurityTokenServiceClient();
}
/**
* Constructs a new STSAssumeRoleSessionCredentialsProvider, which will use
* the specified long lived AWS credentials to make a request to the AWS
* Security Token Service (STS), uses the provided {@link #roleArn} to
* assume a role and then request short lived session credentials, which
* will then be returned by this class's {@link #getCredentials()} method.
*
* @param longLivedCredentials
* The main AWS credentials for a user's account.
* @param roleArn
* The ARN of the Role to be assumed.
* @param roleSessionName
* An identifier for the assumed role session.
*/
public STSAssumeRoleSessionCredentialsProvider(AWSCredentials longLivedCredentials, String roleArn,
String roleSessionName) {
this(longLivedCredentials, roleArn, roleSessionName, new ClientConfiguration());
}
/**
* Constructs a new STSAssumeRoleSessionCredentialsProvider, which will use
* the specified long lived AWS credentials to make a request to the AWS
* Security Token Service (STS), uses the provided {@link #roleArn} to
* assume a role and then request short lived session credentials, which
* will then be returned by this class's {@link #getCredentials()} method.
*
* @param longLivedCredentials
* The main AWS credentials for a user's account.
* @param roleArn
* The ARN of the Role to be assumed.
* @param roleSessionName
* An identifier for the assumed role session.
* @param clientConfiguration
* Client configuration connection parameters.
*/
public STSAssumeRoleSessionCredentialsProvider(AWSCredentials longLivedCredentials, String roleArn,
String roleSessionName, ClientConfiguration clientConfiguration) {
this.roleArn = roleArn;
this.roleSessionName = roleSessionName;
securityTokenService = new AWSSecurityTokenServiceClient(longLivedCredentials, clientConfiguration);
}
/**
* Constructs a new STSAssumeRoleSessionCredentialsProvider, which will use
* the specified credentials provider (which vends long lived AWS
* credentials) to make a request to the AWS Security Token Service (STS),
* usess the provided {@link #roleArn} to assume a role and then request
* short lived session credentials, which will then be returned by this
* class's {@link #getCredentials()} method.
*
* @param longLivedCredentialsProvider
* Credentials provider for the main AWS credentials for a user's
* account.
* @param roleArn
* The ARN of the Role to be assumed.
* @param roleSessionName
* An identifier for the assumed role session.
*/
public STSAssumeRoleSessionCredentialsProvider(AWSCredentialsProvider longLivedCredentialsProvider, String roleArn,
String roleSessionName) {
this.roleArn = roleArn;
this.roleSessionName = roleSessionName;
securityTokenService = new AWSSecurityTokenServiceClient(longLivedCredentialsProvider);
}
/**
* Constructs a new STSAssumeRoleSessionCredentialsProvider, which will use
* the specified credentials provider (which vends long lived AWS
* credentials) to make a request to the AWS Security Token Service (STS),
* uses the provided {@link #roleArn} to assume a role and then request
* short lived session credentials, which will then be returned by this
* class's {@link #getCredentials()} method.
*
* @param longLivedCredentialsProvider
* Credentials provider for the main AWS credentials for a user's
* account.
* @param roleArn
* The ARN of the Role to be assumed.
* @param roleSessionName
* An identifier for the assumed role session.
* @param clientConfiguration
* Client configuration connection parameters.
*/
public STSAssumeRoleSessionCredentialsProvider(AWSCredentialsProvider longLivedCredentialsProvider, String roleArn,
String roleSessionName, ClientConfiguration clientConfiguration) {
this.roleArn = roleArn;
this.roleSessionName = roleSessionName;
securityTokenService = new AWSSecurityTokenServiceClient(longLivedCredentialsProvider, clientConfiguration);
}
@Override
public AWSCredentials getCredentials() {
if (needsNewSession()) {
startSession();
}
return sessionCredentials;
}
@Override
public void refresh() {
startSession();
}
/**
* Starts a new session by sending a request to the AWS Security Token
* Service (STS) to assume a Role using the long lived AWS credentials. This
* class then vends the short lived session credentials for the assumed Role
* sent back from STS.
*/
private void startSession() {
AssumeRoleResult assumeRoleResult = securityTokenService.assumeRole(new AssumeRoleRequest()
.withRoleArn(roleArn).withDurationSeconds(DEFAULT_DURATION_SECONDS)
.withRoleSessionName(roleSessionName));
Credentials stsCredentials = assumeRoleResult.getCredentials();
sessionCredentials = new BasicSessionCredentials(stsCredentials.getAccessKeyId(),
stsCredentials.getSecretAccessKey(), stsCredentials.getSessionToken());
sessionCredentialsExpiration = stsCredentials.getExpiration();
}
/**
* Returns true if a new STS session needs to be started. A new STS session
* is needed when no session has been started yet, or if the last session is
* within {@link #EXPIRY_TIME_MILLIS} seconds of expiring.
*
* @return True if a new STS session needs to be started.
*/
private boolean needsNewSession() {
if (sessionCredentials == null) {
return true;
}
long timeRemaining = sessionCredentialsExpiration.getTime() - System.currentTimeMillis();
return timeRemaining < EXPIRY_TIME_MILLIS;
}
}