如何使用 java 在具有 IAM 角色的 ec2 实例上访问没有访问凭证的 dynamodb

Question

我想使用 Java 访问 Ec2 实例上的 Dynamodb。此 Ec2 实例已被授予 IAM 角色，我可以使用 aws CLI 直接访问 Dynamodb：aws dynamodb 列表表。现在我尝试通过Java访问Dynamodb。Java代码应该能够承担角色，但它不起作用。

public static void main(String[] args) throws Exception {
    String ROLE_ARN = "arn:aws:iam::....";
    AWSSecurityTokenServiceClient stsClient = new AWSSecurityTokenServiceClient();
    AssumeRoleRequest assumeRequest = new AssumeRoleRequest()
        .withRoleArn(ROLE_ARN)
        .withDurationSeconds(3600)
        .withRoleSessionName("demo");
    AssumeRoleResult assumeResult = stsClient.assumeRole(assumeRequest);
    BasicSessionCredentials temporaryCredentials = new BasicSessionCredentials(
                assumeResult.getCredentials().getAccessKeyId(),
                assumeResult.getCredentials().getSecretAccessKey(),
                assumeResult.getCredentials().getSessionToken());
    AmazonDynamoDBClient client = new AmazonDynamoDBClient(temporaryCredentials)
    DynamoDB dynamoDB = new DynamoDB(client);
    TableCollection<ListTablesResult> tables = dynamoDB.listTables();
    Iterator<Table> iterator_t = tables.iterator();
    System.out.println("Listing table names");
    while (iterator_t.hasNext()) {
        Table table = iterator_t.next();
        System.out.println(table.getTableName());
    }
}

当我在 ec2 实例上运行代码时，我得到了

Exception in thread "main" com.amazonaws.services.securitytoken.model.AWSSecurityTokenServiceException: Not authorized to perform sts:AssumeRole (Service: AWSSecurityTokenService; Status Code: 403; Error Code: AccessDenied; Request ID: 60313562-d462-11e6-a116-5bf8bb6a59ce)
    at com.amazonaws.http.AmazonHttpClient$RequestExecutor.handleErrorResponse(AmazonHttpClient.java:1586)
    at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeOneRequest(AmazonHttpClient.java:1254)
    at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeHelper(AmazonHttpClient.java:1035)
    at com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:747)
    at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:721)
    at com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:704)
    at com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:672)
    at com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:654)
    at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:518)
    at com.amazonaws.services.securitytoken.AWSSecurityTokenServiceClient.doInvoke(AWSSecurityTokenServiceClient.java:1188)
    at com.amazonaws.services.securitytoken.AWSSecurityTokenServiceClient.invoke(AWSSecurityTokenServiceClient.java:1164)
    at com.amazonaws.services.securitytoken.AWSSecurityTokenServiceClient.assumeRole(AWSSecurityTokenServiceClient.java:419)
    at com.spokeo.dynamo_elas.AccessAwsD.main(AccessAwsD.java:stsClient.assumeRole(assumeRequest))

有人知道如何解决这个问题吗？谢谢。

Answer 1

经过长时间的探索，终于想出了以下解决方案。

    AWSCredentialsProvider provider = new InstanceProfileCredentialsProvider();
    AWSCredentials credential = provider.getCredentials();
    AmazonDynamoDBClient client = new AmazonDynamoDBClient(credential);
    client.setRegion(Region.getRegion(Regions.US_WEST_2));
    DynamoDB dynamoDB = new DynamoDB(client);
    TableCollection<ListTablesResult> tables = dynamoDB.listTables();

此外，pom.xml中的依赖项需要正确配置以避免冲突，例如， com.amazonaws aws-java-sdk 1.11.72

    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.5.2</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.8.5</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.dataformat/jackson-dataformat-cbor -->
    <dependency>
        <groupId>com.fasterxml.jackson.dataformat</groupId>
        <artifactId>jackson-dataformat-cbor</artifactId>
        <version>2.8.5</version>
    </dependency>

Answer 2

当我这样做时，我从来没有对这个角色做任何具体的事情 - 事实上，我不知道我正在使用什么角色。 我使用类似的东西：

AWSCredentialsProviderChain credentialsProvider;
try {
    credentialsProvider = new DefaultAWSCredentialsProviderChain();
}
catch (Exception e) {
    throw new RuntimeException("Error loading credentials", e);
}
AmazonDynamoDBClient client = new AmazonDynamoDBClient(credentialsProvider);

使用默认提供程序的优点是，如果我使用 ~/.aws/credentials 在本地开发，则会使用它。 如果我在具有 IAM 凭证的 EC2 上，则使用它。