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<?php
namespace Aws\Credentials;
use Aws;
use Aws\CacheInterface;
use Aws\Exception\CredentialsException;
use GuzzleHttp\Promise;
/**
* Credential providers are functions that accept no arguments and return a
* promise that is fulfilled with an {@see \Aws\Credentials\CredentialsInterface}
* or rejected with an {@see \Aws\Exception\CredentialsException}.
*
* <code>
* use Aws\Credentials\CredentialProvider;
* $provider = CredentialProvider::defaultProvider();
* // Returns a CredentialsInterface or throws.
* $creds = $provider()->wait();
* </code>
*
* Credential providers can be composed to create credentials using conditional
* logic that can create different credentials in different environments. You
* can compose multiple providers into a single provider using
* {@see Aws\Credentials\CredentialProvider::chain}. This function accepts
* providers as variadic arguments and returns a new function that will invoke
* each provider until a successful set of credentials is returned.
*
* <code>
* // First try an INI file at this location.
* $a = CredentialProvider::ini(null, '/path/to/file.ini');
* // Then try an INI file at this location.
* $b = CredentialProvider::ini(null, '/path/to/other-file.ini');
* // Then try loading from environment variables.
* $c = CredentialProvider::env();
* // Combine the three providers together.
* $composed = CredentialProvider::chain($a, $b, $c);
* // Returns a promise that is fulfilled with credentials or throws.
* $promise = $composed();
* // Wait on the credentials to resolve.
* $creds = $promise->wait();
* </code>
*/
class CredentialProvider
{
const ENV_KEY = 'AWS_ACCESS_KEY_ID';
const ENV_SECRET = 'AWS_SECRET_ACCESS_KEY';
const ENV_SESSION = 'AWS_SESSION_TOKEN';
const ENV_PROFILE = 'AWS_PROFILE';
/**
* Create a default credential provider that first checks for environment
* variables, then checks for the "default" profile in ~/.aws/credentials,
* then checks for "profile default" profile in ~/.aws/config (which is
* the default profile of AWS CLI), then tries to make a GET Request to
* fetch credentials if Ecs environment variable is presented, and finally
* checks for EC2 instance profile credentials.
*
* This provider is automatically wrapped in a memoize function that caches
* previously provided credentials.
*
* @param array $config Optional array of ecs/instance profile credentials
* provider options.
*
* @return callable
*/
public static function defaultProvider(array $config = [])
{
$localCredentialProviders = self::localCredentialProviders();
$remoteCredentialProviders = self::remoteCredentialProviders($config);
return self::memoize(
call_user_func_array(
'self::chain',
array_merge($localCredentialProviders, $remoteCredentialProviders)
)
);
}
/**
* Create a credential provider function from a set of static credentials.
*
* @param CredentialsInterface $creds
*
* @return callable
*/
public static function fromCredentials(CredentialsInterface $creds)
{
$promise = Promise\promise_for($creds);
return function () use ($promise) {
return $promise;
};
}
/**
* Creates an aggregate credentials provider that invokes the provided
* variadic providers one after the other until a provider returns
* credentials.
*
* @return callable
*/
public static function chain()
{
$links = func_get_args();
if (empty($links)) {
throw new \InvalidArgumentException('No providers in chain');
}
return function () use ($links) {
/** @var callable $parent */
$parent = array_shift($links);
$promise = $parent();
while ($next = array_shift($links)) {
$promise = $promise->otherwise($next);
}
return $promise;
};
}
/**
* Wraps a credential provider and caches previously provided credentials.
*
* Ensures that cached credentials are refreshed when they expire.
*
* @param callable $provider Credentials provider function to wrap.
*
* @return callable
*/
public static function memoize(callable $provider)
{
return function () use ($provider) {
static $result;
static $isConstant;
// Constant credentials will be returned constantly.
if ($isConstant) {
return $result;
}
// Create the initial promise that will be used as the cached value
// until it expires.
if (null === $result) {
$result = $provider();
}
// Return credentials that could expire and refresh when needed.
return $result
->then(function (CredentialsInterface $creds) use ($provider, &$isConstant, &$result) {
// Determine if these are constant credentials.
if (!$creds->getExpiration()) {
$isConstant = true;
return $creds;
}
// Refresh expired credentials.
if (!$creds->isExpired()) {
return $creds;
}
// Refresh the result and forward the promise.
return $result = $provider();
});
};
}
/**
* Wraps a credential provider and saves provided credentials in an
* instance of Aws\CacheInterface. Forwards calls when no credentials found
* in cache and updates cache with the results.
*
* Defaults to using a simple file-based cache when none provided.
*
* @param callable $provider Credentials provider function to wrap
* @param CacheInterface $cache Cache to store credentials
* @param string|null $cacheKey (optional) Cache key to use
*
* @return callable
*/
public static function cache(
callable $provider,
CacheInterface $cache,
$cacheKey = null
) {
$cacheKey = $cacheKey ?: 'aws_cached_credentials';
return function () use ($provider, $cache, $cacheKey) {
$found = $cache->get($cacheKey);
if ($found instanceof CredentialsInterface && !$found->isExpired()) {
return Promise\promise_for($found);
}
return $provider()
->then(function (CredentialsInterface $creds) use (
$cache,
$cacheKey
) {
$cache->set(
$cacheKey,
$creds,
null === $creds->getExpiration() ?
0 : $creds->getExpiration() - time()
);
return $creds;
});
};
}
/**
* Provider that creates credentials from environment variables
* AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, and AWS_SESSION_TOKEN.
*
* @return callable
*/
public static function env()
{
return function () {
// Use credentials from environment variables, if available
$key = getenv(self::ENV_KEY);
$secret = getenv(self::ENV_SECRET);
if ($key && $secret) {
return Promise\promise_for(
new Credentials($key, $secret, getenv(self::ENV_SESSION) ?: NULL)
);
}
return self::reject('Could not find environment variable '
. 'credentials in ' . self::ENV_KEY . '/' . self::ENV_SECRET);
};
}
/**
* Credential provider that creates credentials using instance profile
* credentials.
*
* @param array $config Array of configuration data.
*
* @return InstanceProfileProvider
* @see Aws\Credentials\InstanceProfileProvider for $config details.
*/
public static function instanceProfile(array $config = [])
{
return new InstanceProfileProvider($config);
}
/**
* Credential provider that creates credentials using
* ecs credentials by a GET request, whose uri is specified
* by environment variable
*
* @param array $config Array of configuration data.
*
* @return EcsCredentialProvider
* @see Aws\Credentials\EcsCredentialProvider for $config details.
*/
public static function ecsCredentials(array $config = [])
{
return new EcsCredentialProvider($config);
}
/**
* Credential provider that creates credentials using assume role
*
* @param array $config Array of configuration data
* @return callable
* @see Aws\Credentials\AssumeRoleCredentialProvider for $config details.
*/
public static function assumeRole(array $config=[])
{
return new AssumeRoleCredentialProvider($config);
}
/**
* Credentials provider that creates credentials using an ini file stored
* in the current user's home directory.
*
* @param string|null $profile Profile to use. If not specified will use
* the "default" profile in "~/.aws/credentials".
* @param string|null $filename If provided, uses a custom filename rather
* than looking in the home directory.
*
* @return callable
*/
public static function ini($profile = null, $filename = null)
{
$filename = $filename ?: (self::getHomeDir() . '/.aws/credentials');
$profile = $profile ?: (getenv(self::ENV_PROFILE) ?: 'default');
return function () use ($profile, $filename) {
if (!is_readable($filename)) {
return self::reject("Cannot read credentials from $filename");
}
$data = parse_ini_file($filename, true);
if ($data === false) {
return self::reject("Invalid credentials file: $filename");
}
if (!isset($data[$profile])) {
return self::reject("'$profile' not found in credentials file");
}
if (!isset($data[$profile]['aws_access_key_id'])
|| !isset($data[$profile]['aws_secret_access_key'])
) {
return self::reject("No credentials present in INI profile "
. "'$profile' ($filename)");
}
if (empty($data[$profile]['aws_session_token'])) {
$data[$profile]['aws_session_token']
= isset($data[$profile]['aws_security_token'])
? $data[$profile]['aws_security_token']
: null;
}
return Promise\promise_for(
new Credentials(
$data[$profile]['aws_access_key_id'],
$data[$profile]['aws_secret_access_key'],
$data[$profile]['aws_session_token']
)
);
};
}
/**
* Local credential providers returns a list of local credential providers
* in following order:
* - credentials from environment variables
* - 'default' profile in '.aws/credentials' file
* - 'profile default' profile in '.aws/config' file
*
* @return array
*/
private static function localCredentialProviders()
{
return [
self::env(),
self::ini(),
self::ini('profile default', self::getHomeDir() . '/.aws/config')
];
}
/**
* Remote credential providers returns a list of credentials providers
* for the remote endpoints such as EC2 or ECS Roles.
*
* @param array $config Array of configuration data.
*
* @return array
* @see Aws\Credentials\InstanceProfileProvider for $config details.
* @see Aws\Credentials\EcsCredentialProvider for $config details.
*/
private static function remoteCredentialProviders(array $config = [])
{
if (!empty(getenv(EcsCredentialProvider::ENV_URI))) {
$providers['ecs'] = self::ecsCredentials($config);
}
$providers['instance'] = self::instanceProfile($config);
if (isset($config['credentials'])
&& $config['credentials'] instanceof CacheInterface
) {
foreach ($providers as $key => $provider) {
$providers[$key] = self::cache(
$provider,
$config['credentials'],
'aws_cached_' . $key . '_credentials'
);
}
}
return $providers;
}
/**
* Gets the environment's HOME directory if available.
*
* @return null|string
*/
private static function getHomeDir()
{
// On Linux/Unix-like systems, use the HOME environment variable
if ($homeDir = getenv('HOME')) {
return $homeDir;
}
// Get the HOMEDRIVE and HOMEPATH values for Windows hosts
$homeDrive = getenv('HOMEDRIVE');
$homePath = getenv('HOMEPATH');
return ($homeDrive && $homePath) ? $homeDrive . $homePath : null;
}
private static function reject($msg)
{
return new Promise\RejectedPromise(new CredentialsException($msg));
}
}