NAME
Paws - A Perl SDK for AWS (Amazon Web Services) APIs
SYNOPSIS
use Paws;
my $obj = Paws->service('...');
my $res = $obj->MethodCall(Arg1 => $val1, Arg2 => $val2);
print $res->AttributeFromResult;DESCRIPTION
Paws is an attempt to develop an always up-to-date SDK that covers all possible AWS services.
STATUS
Please consider the SDK is beta quality. The intention of publishing to CPAN is having the community find the SDK, try it, give feedback, etc. Some services are still not working, and some heavy refactoring will still be done to the internals. The external interface to SDK users will try to be kept stable, and changes to it should be notified via ChangeLog
SUPPORTED SERVICES
Paws::MarketplaceCommerceAnalytics
SERVICES CLASSES
Each service in AWS (EC2, CloudFormation, SQS, SNS, etc) has a service class. The service class represents the properties that a web service has (how to call it, what methods it has, how to authenticate, etc). When a service class is instantiated with the right properties (region, if needed, credentials, caller, etc), it will be able to make calls to the service.
Service classes are obtained through
my $service_class = Paws->class_for_service('Service');
my $service_object = $service_class->new(region => '...', caller => ...)Although they are seldom needed. 99% of the time you want service objects directly obtained with the ->service method (read next section) since you have to write less code.
SERVICE OBJECTS
Each Service Object represents the ability to call methods on a service endpoint. Those endpoints are either global, or bound to a region depending on the service. Also, each object can be customized with a credential provider, that tells the object where to obtain credentials for the call (you can get them from the environment, from the filesystem, from the AWS Instance Profile, STS, etc.
To obtain a service object, call the ->service method
use Paws;
my $service = Paws->service('Service');You can pass extra parameters if the service is bound to a region:
my $service = Paws->service('Service', region => 'us-east-1');These parameters are basically passed to the service class constructor
AUTHENTICATION
Service classes by default try to authenticate with a chained authenticator. The chained authenticator tries to first find credentials in your environment variables AWS_ACCESS_KEY and AWS_SECRET_KEY (note that AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY are also scanned for compatibility with the official SDKs). Second, it will look for credentials in the default profile of the ~/.aws/credentials or the file in AWS_CONFIG_FILE env variable (an ini-formatted file). Last, if no environment variables are found, then a call to retrieve Role credentials is done. If your instance is running on an AWS instance, and has a Role assigned, the SDK will automatically retrieve credentials to call any services that the instances Role permits.
Please never burn credentials into your code. That's why the methods for passing an explicit access key and secret key are not documented.
So, instantiating a service with
my $ec2 = Paws->service('EC2', region => 'eu-west-1');we get an service object that will try to authenticate with environment, credential file, or an instance role.
When instantiating a service object, you can also pass a custom credential provider:
use Paws::Credential::STS;
my $cred_provider = Paws::Credential::STS->new(
Name => 'MyName',
DurationSeconds => 900,
Policy => '{"Version":"2012-10-17","Statement":[{"Effect": "Allow","Action":["ec2:DescribeInstances"],"Resource":"*"}]}'
);
my $ec2 = Paws->service('EC2', credentials => $cred_provider, region => 'eu-west-1');In this example we instance a service object that uses the STS service to create temporary credentials that only let the service object call DescribeInstances.
Paws bundles some pre-baked credential providers:
Paws::Credential::ProviderChain - Gets credentials from a list of providers, returning the first provider to return credentials
Paws::Credential::Environment - Gets credentials from environment variables
Paws::Credential::File - Gets credentials from AWS SDK config files
Paws::Credential::InstanceProfile - Gets credentials from the InstanceProfile (Role) of the running instance
Paws::Credential::STS - Gets temporary credentials from the Secure Token Service
Paws::Credential::AssumeRole - Gets temporary credentials with AssumeRole
Paws::Credential::AssumeRoleWithSAML - Gets temporary credentials with AssumeRoleWithSAML
Paws::Credential::Explicit - Gets credentials specified in the code
Using Service objects (Calling APIs)
Each API call is represented as a method call with the same name as the API call. The arguments to the call are passed as lists (named parameters) to the call. So, to call DescribeInstances on the EC2 service:
my $result = $ec2->DescribeInstances;The DescribeInstances call has no required parameters, but if needed, we can pass them in (you can look them up in Paws::EC2 and see detail in Paws::EC2::DescribeInstances
my $result = $ec2->DescribeInstances(MaxResults => 5);If the parameter is an Array:
my $result = $ec2->DescribeInstances(InstanceIds => [ 'i-....' ]);If the parameter to be passed in is a complex value (an object)
my $result = $ec2->DescribeInstances(Filters => [ { Name => '', Value => '' } ])RETURN VALUES
The AWS APIs return nested datastructures in various formats. The SDK converts these datastructures into objects that can then be used as wanted.
my $private_dns = $result->Reservations->[0]->Instances->[0]->PrivateDnsName;CONFIGURATION
Paws instances have a configuration. The configuration is basically a specification of values that will be passed to the service method each time it's called
# the credentials and the caller keys accept an instance or the name of a class as a
# string (the class will be loaded and the constructor of that class will be automatically called
my $paws1 = Paws->new(config => { credentials => MyCredProvider->new, region => 'eu-west-1' });
my $paws2 = Paws->new(config => { caller => 'MyCustomCaller' });
# EC2 service with MyCredProvider in eu-west-1
my $ec2 = $paws1->service('EC2');
# DynamoDB service with MyCustomCaller in us-east-1. region is needed because it's not in the config
my $ddb = $paws2->service('DynamoDB', region => 'us-east-1');
# DynamoDB in eu-west-1 with MyCredProvider
my $other_ddb = $paws1->service('DynamoDB');The attributes that can be configured are:
credentials
Accepts a string which value is the name of a class, or an already instantiated object. If a string is passed, the class will be loaded, and the constructor called (without parameters). Also, the resulting instance or the already instantiated object has to have the Paws::Credential role.
caller
Accepts a string which value is the name of a class, or an already instantiated object. If a string is passed, the class will be loaded, and the constructor called (without parameters). Also, the resulting instance or the already instantiated object has to have the Paws::Net::CallerRole role.
region
A string representing the region that service objects will be instantiated with. Most services need a region specified, meaning that you will have to specify the desired region every time you call the service method.
my $cfn = Paws->service('CloudFormation', region => 'eu-west-1');Some services (like IAM) are global, so they don't need their region specified:
my $iam = Paws->service('IAM');A special service is STS, which by default has a global endpoint, but you can also specify regional endpoints
my $global_sts = Paws->service('STS');
my $regional_sts = Paws->service('STS', region => 'eu-west-1');endpoint
Paws needs to send HTTP requests to different URLS (endpoints) depending on the service and the region. URLs are normally automatically derived by specifying the region, but for special cases, like pointing to "fake-sqs" or "fake-s3" services, you can:
Paws->service('SQS', endpoint => 'http://localhost:3000', region => 'eu-west-1');Some services, like the MachineLearning predictor API want you to specify a custom endpoint:
my $model = $ml->GetMLModel(MLModelId => $model_id);
my $predictor = Paws->service('ML', endpoint => $model->EndpointInfo->EndpointUrl, region => 'eu-west-1');
$predictor->...Pluggability
Credential Provider Pluggability
Credential classes need to have the Role Paws::Credential applied. This obliges them to implement access_key, secret_key and session_token methods. The obtention of this data can be customized to be retrieved whereever the developer considers useful (files, environment, other services, etc). Take a look at the Paws::Credential::XXXX namespace to find already implemented credential providers.
The credential objects' access_key, secret_key and session_token methods will be called each time an API call has to be signed.
Caller Pluggability
Caller classes need to have the Role Paws::Net::CallerRole applied. This obliges them to implement the do_call method. Tests use this interface to mock calls and responses to the APIs (without using the network).
The caller instance is responsable for doing the network Input/Output with some type of HTTP request library, and returning the Result from the API.
These callers are included and supported in Paws:
Paws::Net::Caller: Uses HTTP::Tiny. It's the default caller for Paws
Paws::Net::MojoAsyncCaller: Experimental asyncronous IO caller. Paws method calls return futures instead of results
Paws::Net::LWPCaller: Uses LWP. LWP supports HTTPS proxies, so Paws can call AWS from behind an HTTPS proxy.
Paws::Net::FurlCaller: Uses Furl: a lightning fast HTTP client
Optimization
Preloading services and operations
Paws->preload_service($service)
Paws->preload_service($service, @methods)Paws manages a lot of objects that are loaded dynamically as needed. This causes high memory consumption if you do operations with Paws in a forked environment because each child loads a separate copy of all the classes it needs to do the calls. Paws provides the preload_service operation. Call it with the name of the service before forking off so your server can benefit from copy on write memory sharing. The parent class will load all the classes needed so that child processes don't need to load them.
Some classes have lot's of calls, so preloading them can be quite expensive. If you call preload_service with a list of the methods you will call, it will only load classes needed for those calls. This is specially useful for Paws::EC2, for example.
Preloading doesn't change the usage of Paws. That means that all services and methods still work without any change, just that if they're not preloaded they'll be loaded at runtime.
Immutabilizing classes
Paws objects are programmed with Moose (the Modern Perl Object Framework). Moose objects can be immutibilized so that method calls perform better, at the cost of startup time. If you deem your usage of Paws to be long-lived, you can call
Paws->default_config->immutable(1);as early as possible in the code. Very important that the immutable flag be activated before calling preload_service.
AUTHOR
Jose Luis Martinez
CPAN ID: JLMARTIN
CAPSiDE
jlmartinez@capside.comSEE ALSO
http://aws.amazon.com/documentation/
https://github.com/pplu/aws-sdk-perl
BUGS and SOURCE
The source code is located here: https://github.com/pplu/aws-sdk-perl
Please report bugs to: https://github.com/pplu/aws-sdk-perl/issues
COPYRIGHT and LICENSE
Copyright (c) 2015 by Jose Luis Martinez Torres
This code is distributed under the Apache 2 License. The full text of the license can be found in the LICENSE file included with this module.
CONTRIBUITIONS
CAPSiDE (http://www.capside.com) for letting Paws be contributed in an open source model and giving me time to build and maintain it regularly
Luis Alberto Gimenez (@agimenez) for - The git-fu cleaning up the "pull other sdks" code - Credential Providers code - Fixes for users that have no HOME env variable - FileCaller to fully mock responses
Srinvas (@kidambisrinivas) for testing, bug reporting and fixing
juair10 for corrections and testing
CHORNY for CPAN and cpanfile packaging corrections
Iñigo Tejedor for service endpoint resolution based on rules
codehead for helping fix SQS Queue Maps
mbartold for helping fix SQS MessageBatch functionality
coreymayer for reporting bug in RestXmlCaller
arc (Aaron Crane) for documentation patches
dtikhonov for LWP Caller and bug reporting/fixing
vivus-ignis for DynamoDB bug reporting and test scripts for DynamoDB
karenetheridge for bug reporting, pull requests and help
ioanrogers for fixing unicode issues in tests
ilmari for fixing issues with timestamps in Date and X-Amz-Date headers, test fixes and 5.10 support fixes, documentation issue fixes for S3, CloudFront and Route53, help with number stringification
stevecaldwell77 for contributing support for temporary credentials in S3
Ryan Olson (BeerBikesBBQ) for contributing documentation fixes
Roger Pettett for testing and contributing fixes for tests on MacOSX
Henri Yandell for help with licensing issues
Oriol Soriano (@ureesoriano) for contribution to API builders
H. Daniel Cesario (@maneta) for devel setup instructions on RH and MacOSX
Glen van Ginkel for contributions to get S3 working
Javier Arellano for discovering Tagging bug
Ioan Rogers for contributing AssumeRoleWithSAML with ADFS auth example
Miquel Soriano for reporting a bug with DescribeAutoScalingGroups
Albert Bendicho (wiof) for contributing better retry logic
Brian Hartsock for better handling of XMLResponse exceptions
rpcme for reporting various bugs in the SDK
glenveegee for lots of work sorting out the S3 implementation
Grinzz for many bugs, suggestions and fixes
Dakkar for solving issues with parameter passing
Arthur Axel fREW Schmidt for speeding up credential refreshing
PopeFelix for solving issues around S3 and MojoAsyncCaller
meis for contributing Paws::Credential::Explicit
sven-schubert for contributing fixes to RestXML services, working on fixing S3 to work correctly.
SeptamusNonovant for fixing paginators in non-callback mode
gadgetjunkie for contributing the ECS credential provider