Assume an IAM role - AWS SDK for PHP
Using IAM roles for Amazon EC2 instance variable credentialsUsing IAM roles for Amazon ECS tasksAssuming an IAM role in another AWS accountUsing an IAM role with web identityAssume role with profile

Assume an IAM role

Using IAM roles for Amazon EC2 instance variable credentials

If you’re running your application on an Amazon EC2 instance, the preferred way to provide credentials to make calls to AWS is to use an IAM role to get temporary security credentials.

When you use IAM roles, you don’t need to worry about credential management from your application. They allow an instance to “assume” a role by retrieving temporary credentials from the Amazon EC2 instance’s metadata server.

The temporary credentials, often referred to as instance profile credentials, allow access to the actions and resources that the role’s policy allows. Amazon EC2 handles all the legwork of securely authenticating instances to the IAM service to assume the role, and periodically refreshing the retrieved role credentials. This keeps your application secure with almost no work on your part. For a list of the services that accept temporary security credentials, see AWS services that work with IAM in the IAM User Guide.

Note

To avoid hitting the metadata service every time, you can pass an instance of Aws\CacheInterface in as the 'credentials' option to a client constructor. This lets the SDK use cached instance profile credentials instead. For details, see Configuration for the AWS SDK for PHP Version 3.

For more information on developing Amazon EC2 applications using the SDKs, see Using IAM roles for Amazon EC2 instances in the AWS SDKs and Tools Reference Guide.

Create and assign an IAM role to an Amazon EC2 instance

  1. Create an IAM client.

    Imports 

    require 'vendor/autoload.php';

use Aws\Iam\IamClient;

    Sample Code 

    $client = new IamClient([
    'region' => 'us-west-2',
    'version' => '2010-05-08'
]);

  2. Create an IAM role with the permissions for the actions and resources you’ll use.

    Sample Code 

    $result = $client->createRole([
    'AssumeRolePolicyDocument' => 'IAM JSON Policy', // REQUIRED
    'Description' => 'Description of Role',
    'RoleName' => 'RoleName', // REQUIRED
]);

  3. Create an IAM instance profile and store the Amazon Resource Name (ARN) from the result.

    Note

    If you use the IAM console instead of the AWS SDK for PHP, the console creates an instance profile automatically and gives it the same name as the role to which it corresponds.

    Sample Code 

    $IPN = 'InstanceProfileName';

$result = $client->createInstanceProfile([
    'InstanceProfileName' => $IPN ,
]);

$ARN = $result['Arn'];
$InstanceID =  $result['InstanceProfileId'];

  4. Create an Amazon EC2 client.

    Imports 

    require 'vendor/autoload.php';

use Aws\Ec2\Ec2Client;

    Sample Code 

    $ec2Client = new Ec2Client([
    'region' => 'us-west-2',
    'version' => '2016-11-15',
]);

  5. Add the instance profile to a running or stopped Amazon EC2 instance. Use the instance profile name of your IAM role.

    Sample Code 

     $result = $ec2Client->associateIamInstanceProfile([
    'IamInstanceProfile' => [
        'Arn' => $ARN,
        'Name' => $IPN,
    ],
    'InstanceId' => $InstanceID
]);

For more information, see IAM Roles for Amazon EC2 in the Amazon EC2 User Guide for Linux Instances.

Using IAM roles for Amazon ECS tasks

A task in Amazon Elastic Container Service (Amazon ECS) can assume an IAM role to make AWS API calls. This is a strategy for managing credentials for your applications to use, similar to how Amazon EC2 instance profiles provide credentials to Amazon EC2 instances.

Instead of creating and distributing long-term AWS credentials to containers or using the Amazon EC2 instance’s role, you can associate an IAM role that uses temporary credentials with an ECS task definition or RunTask API operation.

For more information on using IAM roles that container tasks can assume, see the Task IAM role topic in the Amazon ECS Developer Guide. For examples of using the task IAM role in the form of a taskRoleArn in task definitions, see Example task definitions also in the Amazon ECS Developer Guide.

Assuming an IAM role in another AWS account

When you work in an AWS account (Account A) and want to assume a role in another account (Account B), you must first create an IAM role in Account B. This role allows entities in your account (Account A) to perform specific actions in Account B. For more information about cross-account access, see Tutorial: Delegate Access Across AWS Accounts Using IAM Roles.

After you create a role in Account B, record the Role ARN. You will use this ARN when you assume the role from Account A. You assume the role using the AWS credentials associated with your entity in Account A.

Create an AWS STS client with credentials for your AWS account. In the following, we used a credentials profile, but you can use any method. With the newly created AWS STS client, call assume-role and provide a custom sessionName. Retrieve the new temporary credentials from the result. Credentials last an hour by default.

Sample Code 

$stsClient = new Aws\Sts\StsClient([
    'profile' => 'default',
    'region' => 'us-east-2',
    'version' => '2011-06-15'
]);

$ARN = "arn:aws:iam::123456789012:role/xaccounts3access";
$sessionName = "s3-access-example";

$result = $stsClient->AssumeRole([
      'RoleArn' => $ARN,
      'RoleSessionName' => $sessionName,
]);

 $s3Client = new S3Client([
    'version'     => '2006-03-01',
    'region'      => 'us-west-2',
    'credentials' =>  [
        'key'    => $result['Credentials']['AccessKeyId'],
        'secret' => $result['Credentials']['SecretAccessKey'],
        'token'  => $result['Credentials']['SessionToken']
    ]
]);

For more information, see Using IAM Roles or AssumeRole in the AWS SDK for PHP API Reference.

Using an IAM role with web identity

Web Identity Federation enables customers to use third-party identity providers for authentication when accessing AWS resources. Before you can assume a role with web identity, you must create an IAM role and configure a web identity provider (IdP). For more information, see Creating a Role for Web Identity or OpenID Connect Federation (Console).

After creating an identity provider and creating a role for your web identity, use an AWS STS client to authenticate a user. Provide the webIdentityToken and ProviderId for your identity, and the Role ARN for the IAM role with permissions for the user.

Sample Code 

$stsClient = new Aws\Sts\StsClient([
    'profile' => 'default',
    'region' => 'us-east-2',
    'version' => '2011-06-15'
]);

$ARN = "arn:aws:iam::123456789012:role/xaccounts3access";
$sessionName = "s3-access-example";
$duration = 3600;

$result = $stsClient->AssumeRoleWithWebIdentity([
      'WebIdentityToken' => "FACEBOOK_ACCESS_TOKEN",
      'ProviderId' => "graph.facebook.com",
      'RoleArn' => $ARN,
      'RoleSessionName' => $sessionName,
]);

 $s3Client = new S3Client([
    'version'     => '2006-03-01',
    'region'      => 'us-west-2',
    'credentials' =>  [
        'key'    => $result['Credentials']['AccessKeyId'],
        'secret' => $result['Credentials']['SecretAccessKey'],
        'token'  => $result['Credentials']['SessionToken']
    ]
]);

For more information, see AssumeRoleWithWebIdentity—Federation Through a Web-based Identity Provider or AssumeRoleWithWebIdentity in the AWS SDK for PHP API Reference.

Assume role with profile

Define profiles in ~/.aws/credentials

You can configure the AWS SDK for PHP to use an IAM role by defining a profile in ~/.aws/credentials.

Create a new profile with the role_arn setting for the role you want assumed. Also include the source_profile setting for another profile with credentials that have permissions to assume the IAM role. For more details on these configuration settings, see Assume role credentials in the AWS SDKs and Tools Reference Guide.

For example, in the following ~/.aws/credentials, the project1 profile sets the role_arn and specifies the default profile as the source for credentials to verify that the entity associated with them can assume the role.

[project1]
role_arn = arn:aws:iam::123456789012:role/testing
source_profile = default
role_session_name = OPTIONAL_SESSION_NAME

[default]
aws_access_key_id = YOUR_AWS_ACCESS_KEY_ID
aws_secret_access_key = YOUR_AWS_SECRET_ACCESS_KEY
aws_session_token= YOUR_AWS_SESSION_TOKEN

If you set the AWS_PROFILE environment variable, or you use profile parameter when you instantiate a service client, the role specified in project1 is assumed, using the default profile as the source credentials.

The following snippet shows the use of the profile parameter in an S3Client constructor. The S3Client will have the permissions associated with the role associated with the project1 profile.

$s3 = new Aws\S3\S3Client([
    'region' => 'us-east-1',
    'version' => '2006-03-01',
    'profile' => 'project1'
]);

Define profiles in ~/.aws/config

The ~/.aws/config file can also contain profiles that you want to be assumed. If you set the environment variable AWS_SDK_LOAD_NONDEFAULT_CONFIG, the SDK for PHP loads profiles from the config file. When AWS_SDK_LOAD_NONDEFAULT_CONFIG is set, the SDK loads profiles from both ~/.aws/config and ~/.aws/credentials. Profiles from ~/.aws/credentials are loaded last and take precedence over a profile from ~/.aws/config with the same name. Profiles from either location can serve as the source_profile or the profile to be assumed.

The following example uses the project1 profile defined in the config file and the default profile in the credentials file. The AWS_SDK_LOAD_NONDEFAULT_CONFIG is also set.

# Profile in ~/.aws/config.

[profile project1]
role_arn = arn:aws:iam::123456789012:role/testing
source_profile = default
role_session_name = OPTIONAL_SESSION_NAME
# Profile in ~/.aws/credentials.

[default]
aws_access_key_id = YOUR_AWS_ACCESS_KEY_ID
aws_secret_access_key = YOUR_AWS_SECRET_ACCESS_KEY
aws_session_token= YOUR_AWS_SESSION_TOKEN

When the S3Client constructor runs that is shown the following snippet, the role defined in the project1 profile will be assumed using credentials associated with the default profile.

$s3 = new Aws\S3\S3Client([
    'region' => 'us-east-1',
    'version' => '2006-03-01',
    'profile' => 'project1'
]);