uk.co.lucasweb.aws.v4.signer.credentials.AwsCredentialsProviderChain Maven / Gradle / Ivy

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A lightweight, zero-dependency implementation of the AWS V4 signing algorithm

There is a newer version: 1.3

/*
  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://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.

  Copyright 2016 the original author or authors.
 */
package uk.co.lucasweb.aws.v4.signer.credentials;

import uk.co.lucasweb.aws.v4.signer.SigningException;
import uk.co.lucasweb.aws.v4.signer.functional.Streams;

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

/**
 * @author Richard Lucas
 */
public class AwsCredentialsProviderChain {

    static final String ACCESS_KEY_ENV_VAR = "AWS_ACCESS_KEY";
    static final String SECRET_KEY_ENV_VAR = "AWS_SECRET_KEY";
    static final String ACCESS_KEY_SYSTEM_PROPERTY = "aws.accessKeyId";
    static final String SECRET_KEY_SYSTEM_PROPERTY = "aws.secretKey";

    EnvironmentVarResolver environmentVarResolver;

    private final List providers;

    public AwsCredentialsProviderChain() {
        this(new EnvironmentVarResolver());
    }

    public AwsCredentialsProviderChain(EnvironmentVarResolver environmentVarResolver) {
        this.environmentVarResolver = environmentVarResolver;
        this.providers = new ArrayList<>();
        this.providers.add(systemPropertiesProvider());
        this.providers.add(environmentProvider());
    }

    public AwsCredentials getCredentials() {
        return providers.stream()
                .flatMap(p -> Streams.streamopt(p.getCredentials()))
                .findFirst()
                .orElseThrow(() -> new SigningException("no AWS credentials were provided"));
    }

    AwsCredentialsProvider environmentProvider() {
        return () -> getAwsCredentials(environmentVarResolver.getenv(ACCESS_KEY_ENV_VAR),
                                       environmentVarResolver.getenv(SECRET_KEY_ENV_VAR));
    }

    AwsCredentialsProvider systemPropertiesProvider() {
        return () -> getAwsCredentials(System.getProperty(ACCESS_KEY_SYSTEM_PROPERTY),
                                       System.getProperty(SECRET_KEY_SYSTEM_PROPERTY));
    }

    private Optional getAwsCredentials(String accessKey, String secretKey) {

        Optional optionalAccessKey = Optional.ofNullable(accessKey);
        Optional optionalSecretKey = Optional.ofNullable(secretKey);
        if (optionalAccessKey.isPresent() && optionalSecretKey.isPresent()) {
            return Optional.of(new AwsCredentials(optionalAccessKey.get(), optionalSecretKey.get()));
        } else {
            return Optional.empty();
        }
    }

    static class EnvironmentVarResolver {
        String getenv(String name) {
            return System.getenv(name);
        }
    }


}