使用AWS PHP时拒绝AWS假定角色访问

Question

我在使用AWS PHP SDK时遇到问题 从apache服务器（PHP SDK）调用AssumeRole时，出现以下错误

    Error executing "AssumeRole" on "https://sts.amazonaws.com"; 
    AWS HTTP error: Client error: `POST https://sts.amazonaws.com` resulted in a `403 Forbidden` 
response: Sender AccessDeni (truncated...) AccessDenied (client): Access denied - Sender AccessDenied Access denied

我测试了该命令以使用AWS CLI在同一台ec2计算机中扮演角色，并且运行良好。

这是我使用的代码。

const AccessKey = "<AccessKey>";
    const SecretAccessKey = "<SecretAccessKey>";
    const AccountID = "<AccountID>";
    const Name_space = "default";  // leave this as default

    use Aws\Sts\StsClient;
    use Aws\Sts\StsException;     

 try {
  $sts = new Aws\Sts\StsClient([
            'region' => 'us-east-1',
            'version' => 'latest',
            'credentials  ' => array('key' => AccessKey,
               'secret' => SecretAccessKey)
        ]);



 $session = $sts->assumeRole([
           'DurationSeconds' => 900,
           'RoleArn' => '<arn>', // REQUIRED
           'RoleSessionName' => testSession, // REQUIRED
      ]);

 } catch (Exception $e) {

        exit($e->getMessage());
    }

-已编辑以添加以下内容-

用户有承担角色的政策

{
    "Version": "2012-10-17",
    "Statement": {
        "Effect": "Allow",
        "Action": "sts:AssumeRole",
        "Resource": "<role arn>"
    }
}

这是角色的信任关系

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "ec2.amazonaws.com",
        "AWS": "<user arn>"
      },
      "Action": "sts:AssumeRole"
    }
  ]
}