org.kuali.maven.wagon.auth.MavenAwsCredentialsProviderChain.java Source code

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Here is the source code for org.kuali.maven.wagon.auth.MavenAwsCredentialsProviderChain.java

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/**
 * Copyright 2010-2014 The Kuali Foundation
 *
 * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
 *
 * 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.kuali.maven.wagon.auth;

import java.util.ArrayList;
import java.util.List;

import org.apache.maven.wagon.authentication.AuthenticationInfo;

import com.amazonaws.auth.AWSCredentialsProvider;
import com.amazonaws.auth.AWSCredentialsProviderChain;
import com.amazonaws.auth.EnvironmentVariableCredentialsProvider;
import com.amazonaws.auth.InstanceProfileCredentialsProvider;
import com.amazonaws.auth.SystemPropertiesCredentialsProvider;
import com.google.common.base.Optional;

/**
 * This chain searches for AWS credentials in system properties -> environment variables -> ~/.m2/settings.xml -> Amazon's EC2 Instance Metadata Service
 */
public final class MavenAwsCredentialsProviderChain extends AWSCredentialsProviderChain {

    public MavenAwsCredentialsProviderChain(Optional<AuthenticationInfo> auth) {
        super(getProviders(auth));
    }

    private static AWSCredentialsProvider[] getProviders(Optional<AuthenticationInfo> auth) {
        List<AWSCredentialsProvider> providers = new ArrayList<AWSCredentialsProvider>();

        // System properties always win
        providers.add(new SystemPropertiesCredentialsProvider());

        // Then fall through to environment variables
        providers.add(new EnvironmentVariableCredentialsProvider());

        // Then fall through to settings.xml
        providers.add(new AuthenticationInfoCredentialsProvider(auth));

        // Then fall through to Amazon's EC2 Instance Metadata Service
        // http://docs.aws.amazon.com/AWSSdkDocsJava/latest/DeveloperGuide/java-dg-roles.html
        // This allows you setup an IAM role, attach that role to an EC2 Instance at launch time,
        // and thus automatically provide the wagon with the credentials it needs
        providers.add(new InstanceProfileCredentialsProvider());

        return providers.toArray(new AWSCredentialsProvider[providers.size()]);
    }

}