In order to authenticate requests, AWS services require you to provide your AWS access keys, also known as your AWS access key ID and secret access key. In the AWS SDK for PHP, these access keys are often referred to collectively as your credentials. This guide demonstrates how to provide your credentials to the AWS SDK for SDK.
There are many ways to provide credentials:
The technique that you use to provide credentials to the SDK for your application is entirely up to you. Please read each section on this page to determine what is the best fit for you. What you choose will depend on many different factors, including:
Regardless of the technique used, it is encouraged that you follow the IAM Best Practices when managing your credentials, including the recommendation to not use your AWS account's root credentials. Instead, create separate IAM users with their own access keys for each project, and tailor the permissions of the users specific to those projects.
In general, it is recommended that you use IAM roles when running your application on Amazon EC2 and use credential profiles or environment variables elsewhere.
If you do not provide credentials to a client object at the time of its instantiation (e.g., via the client's factory
method or via a service builder configuration), the SDK will attempt to find credentials in your environment when you
call your first operation. The SDK will use the
$_SERVER superglobal and/or
getenv() function to look for the
AWS_SECRET_ACCESS_KEY environment variables. These credentials are referred to as
Using IAM roles is the preferred technique for providing credentials to applications running on Amazon EC2. IAM roles remove the need to worry about credential management from your application. They allow an instance to "assume" a role by retrieving temporary credentials from the EC2 instance's metadata server. These temporary credentials, often referred to as instance profile credentials, allow access to the actions and resources that the role's policy allows.
When launching an EC2 instance, you can choose to associate it with an IAM role. Any application running on that EC2 instance is then allowed to assume the associated role. 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, keeping your application secure with almost no work on your part.
If you do not explicitly provide credentials to the client object and no environment variable credentials are available, the SDK attempts to retrieve instance profile credentials from an Amazon EC2 instance metadata server. These credentials are available only when running on Amazon EC2 instances that have been configured with an IAM role.
Instance profile credentials and other temporary credentials generated by the AWS Security Token Service (AWS STS) are not supported by every service. Please check if the service you are using supports temporary credentials by reading AWS Services that Support AWS STS.
For more information, see IAM Roles for Amazon EC2.
While using IAM role credentials is the preferred method for providing credentials to an application running on an Amazon EC2 instance, the roundtrip from the application to the instance metadata server on each request can introduce latency. In these situations, you might find that utilizing a caching layer on top of your IAM role credentials can eliminate the introduced latency.
The easiest way to add a cache to your IAM role credentials is to specify a credentials cache using the
credentials.cache option in a client's factory method or in a service builder configuration file. The
credentials.cache configuration setting should be set to an object that implements Guzzle's
Guzzle\Cache\CacheAdapterInterface (see Guzzle cache adapters). This interface provides an
abstraction layer over various cache backends, including Doctrine Cache, Zend Framework 2 cache, etc.
<?php require 'vendor/autoload.php'; use Doctrine\Common\Cache\FilesystemCache; use Guzzle\Cache\DoctrineCacheAdapter; // Create a cache adapter that stores data on the filesystem $cacheAdapter = new DoctrineCacheAdapter(new FilesystemCache('/tmp/cache')); // Provide a credentials.cache to cache credentials to the file system $s3Client = Aws\S3\S3Client::factory(array( 'credentials.cache' => $cacheAdapter ));
In the preceding example, the addition of
credentials.cache causes credentials to be cached to the local filesystem
using Doctrine's caching system. Every request that uses this cache adapter first
checks if the credentials are in the cache. If the credentials are found in the cache, the client then ensures that the
credentials are not expired. In the event that cached credentials become expired, the client automatically refreshes the
credentials on the next request and populates the cache with the updated credentials.
A credentials cache can also be used in a service builder configuration:
<?php // File saved as /path/to/custom/config.php use Doctrine\Common\Cache\FilesystemCache; use Guzzle\Cache\DoctrineCacheAdapter; $cacheAdapter = new DoctrineCacheAdapter(new FilesystemCache('/tmp/cache')); return array( 'includes' => array('_aws'), 'services' => array( 'default_settings' => array( 'params' => array( 'credentials.cache' => $cacheAdapter ) ) ) );
If you were to use the above configuration file with a service builder, then all of the clients created through the service builder would utilize a shared credentials cache object.
Starting with the AWS SDK for PHP version 2.6.2, you can use an AWS credentials file to specify your credentials. This
is a special, INI-formatted file stored under your HOME directory, and is a good way to manage credentials for your
development environment. The file should be placed at
~ represents your HOME
Using an AWS credentials file offers a few benefits:
The format of the AWS credentials file should look something like the following:
[default] aws_access_key_id = YOUR_AWS_ACCESS_KEY_ID aws_secret_access_key = YOUR_AWS_SECRET_ACCESS_KEY [project1] aws_access_key_id = ANOTHER_AWS_ACCESS_KEY_ID aws_secret_access_key = ANOTHER_AWS_SECRET_ACCESS_KEY
Each section (e.g.,
[project1]), represents a separate credential profile. Profiles can be
referenced from an SDK configuration file, or when you are instantiating a client, using the
<?php use Aws\DynamoDb\DynamoDbClient; // Instantiate a client with the credentials from the project1 profile $dynamoDbClient = DynamoDbClient::factory(array( 'profile' => 'project1', 'region' => 'us-west-2', ));
If no credentials or profiles were explicitly provided to the SDK and no credentials were defined in environment
variables, but a credentials file is defined, the SDK will use the "default" profile. You can change the default
profile by specifying an alternate profile name in the
AWS_PROFILE environment variable.
The SDK allows you to explicitly set your credentials in your project in a few different ways. These techniques are useful for rapid development, integrating with existing configurations systems (e.g., your PHP framework of choice), and using temporary credentials. However, be careful to not hard-code your credentials inside of your applications. Hard-coding your credentials can be dangerous, because it is easy to accidentally commit your credentials into an SCM repository, potentially exposing your credentials to more people than intended. It can also make it difficult to rotate credentials in the future.
The SDK provides a service builder that can be used to share configuration values across multiple clients. The service builder allows you to specify default configuration values (e.g., credentials and regions) that are used by every client. The service builder is configured using either JSON configuration files or PHP scripts that return an array.
The following is an example of a configuration script that returns an array of configuration data that can be used by the service builder:
<?php return array( // Bootstrap the configuration file with AWS specific features 'includes' => array('_aws'), 'services' => array( // All AWS clients extend from 'default_settings'. Here we are // overriding 'default_settings' with our default credentials and // providing a default region setting. 'default_settings' => array( 'params' => array( 'credentials' => array( 'key' => 'YOUR_AWS_ACCESS_KEY_ID', 'secret' => 'YOUR_AWS_SECRET_ACCESS_KEY', ), 'region' => 'us-west-1' ) ) ) );
After creating and saving the configuration file, you need to instantiate a service builder.
<?php use Aws\Common\Aws; // Create the AWS service builder, providing the path to the config file $aws = Aws::factory('/path/to/custom/config.php');
At this point, you can now create clients using the
get() method of the
$s3Client = $aws->get('s3');
A simple way to specify your credentials is by injecting them directly into the factory method when instantiating the client object.
<?php use Aws\S3\S3Client; // Instantiate the S3 client with your AWS credentials $s3Client = S3Client::factory(array( 'credentials' => array( 'key' => 'YOUR_AWS_ACCESS_KEY_ID', 'secret' => 'YOUR_AWS_SECRET_ACCESS_KEY', ) ));
In some cases, you may already have an instance of a
Credentials object. You can use this instead of specifying your
access keys separately.
<?php use Aws\S3\S3Client; use Aws\Common\Credentials\Credentials; $credentials = new Credentials('YOUR_ACCESS_KEY', 'YOUR_SECRET_KEY'); // Instantiate the S3 client with your AWS credentials $s3Client = S3Client::factory(array( 'credentials' => $credentials ));
You may also want to read the section in the Getting Started Guide about using a client's factory method for more details.
AWS Security Token Service (AWS STS) enables you to request limited-privilege, temporary credentials for AWS IAM users or for users that you authenticate via identity federation. One common use case for using temporary credentials is to grant mobile or client-side applications access to AWS resources by authenticating users through third-party identity providers (read more about Web Identity Federation).
Temporary credentials generated by AWS STS are not supported by every service. Please check if the service you are using supports temporary credentials by reading AWS Services that Support AWS STS.
AWS STS has several operations that return temporary credentials, but the
GetSessionToken operation is the simplest
for demonstration purposes. Assuming you have an instance of
Aws\Sts\StsClient stored in the
variable, this is how you call it:
$result = $stsClient->getSessionToken();
The result for
GetSessionToken and the other AWS STS operations always contains a
'Credentials' value. If you
print the result (e.g.,
print_r($result)), it looks like the following:
Array ( ... [Credentials] => Array ( [SessionToken] => '<base64 encoded session token value>' [SecretAccessKey] => '<temporary secret access key value>' [Expiration] => 2013-11-01T01:57:52Z [AccessKeyId] => '<temporary access key value>' ) ... )
You can use temporary credentials with another AWS client by instantiating the client and passing in the values received from AWS STS directly.
use Aws\S3\S3Client; $result = $stsClient->getSessionToken(); $s3Client = S3Client::factory(array( 'credentials' => array( 'key' => $result['Credentials']['AccessKeyId'], 'secret' => $result['Credentials']['SecretAccessKey'], 'token' => $result['Credentials']['SessionToken'] ) ));
You can also construct a
Credentials object and use that when instantiating the client.
use Aws\Common\Credentials\Credentials; use Aws\S3\S3Client; $result = $stsClient->getSessionToken(); $credentials = new Credentials( $result['Credentials']['AccessKeyId'], $result['Credentials']['SecretAccessKey'], $result['Credentials']['SessionToken'] ); $s3Client = S3Client::factory(array('credentials' => $credentials));
However, the best way to provide temporary credentials is to use the
createCredentials() helper method included
StsClient. This method extracts the data from an AWS STS result and creates the
Credentials object for
$result = $stsClient->getSessionToken(); $credentials = $stsClient->createCredentials($result); $s3Client = S3Client::factory(array('credentials' => $credentials));
You can also use the same technique when setting credentials on an existing client object.
$credentials = $stsClient->createCredentials($stsClient->getSessionToken()); $s3Client->setCredentials($credentials);
For more information about why you might need to use temporary credentials in your application or project, see Scenarios for Granting Temporary Access in the AWS STS documentation.
In some cases, you may want to create a client that is not associated with any credentials. This allows you to make anonymous requests to a service. For example, both S3 Objects and CloudSearch Domains can be configured to allow anonymous access.
To create an anonymous client, you can set the
'credentials' option to
$s3Client = S3Client::factory(array('credentials' => false)); // Makes an anonymous request. The Object would need to be publicly readable for this to succeed. $result = $s3Client->getObject(array( 'Bucket' => 'my-bucket', 'Key' => 'my-key', ));