Paws – A Perl AWS SDK

@pplu_io

06/11/2015 - Barcelona

Barcelona Perl Workshop 2015

Jose Luis Martinez

AWS is…• Cloud Computing• Consume computing/database/queuing/etc services via

an API• The biggest datacenter you can think of• With global reach

• Everything is an API

AWS is…

Programmers wet dream

AWS is…

Programmers wet dream

AWS is…

Builders wet dream

Why?Isn’t there support for AWS on CPAN?

AWS Services on CPAN• There are a LOT• EC2, SQS, S3, RDS, DynamoDB, etc• But lots are were missing

• AWS::CLIWrapper is a generic solution too• Shells off to the oficial AWS CLI (python)

I want Perl support for ALL of them

Different authors, different opinions• Default region (eu-west-1 for some, us-east-1 for others)• Different HTTP clients• LWP, HTTP::Tiny, Furl, etc

I want explicit, required, region. Croak if not specifiedPluggable HTTP client?

Different authors, different photo• Some regions not supported due to bugs

• Subtle name changes in region endpoints• Credential handling• Module just covers their needs

I want as broad support as we can get

Credential handling• Roles in AWS help you not have to distribute credentials

(AccessKey and SecretKey)• Support depends on author of module knowing of them

/ needing them

I want support for Instance Roles, STS AssumeRole, Federation for all services

UpToDate-ness• Being up to date depends on authors needs, time, etc• AWS APIs are updated a lot

I want up to date APIs

Lets write an SDK!

Some numbers52 services

Some numbers52 services That was in 2015-09

Some numbers60 services Today (2015-11)

Some numbers60 services

~1600 actions

Some numbers60 services

~1600 actions

~3700 distinct input/output objects

Some numbers60 services

~1600 actions

~3700 distinct input/output objects

~12000 attributes

Write by hand?

Write by hand?

Paws is autogenerated

Using Paws

Authentication• Don’t burn credentials in your code (or even your apps

config)

Use ENV variables AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY

In file ~/.aws/credentials[default]aws_access_key_id=AKIXKDSJFDSFSJDaws_secret_access_key=Gdksjfkso+erkkdjreiw-t

Each AWS API is a “Service Class”• Each Action in the API is a method on the Service Class

• EC2 API -> Paws::EC2 service class• Paws::EC2 objects have methods like• RunInstances• TerminateInstances• DescribeInstances

How do I get an instance of a service class?use Paws;my $ec2 = Paws->service(‘EC2’, region => ‘eu-west-1’);my $iam = Paws->service(‘IAM’);

# $ec2 and $iam are instances of Paws::EC2 and Paws::IAM# they use Paws default config (they just work )

How do I get an instance of a service class? (II)my $paws = Paws->new(config => { region => ‘eu-west-1’, caller => ‘Paws::Net::LWPCaller’, credentials => ‘My::Custom::Credential::Provider’});

my $ec2 = $paws->service(‘EC2’);# ec2 is bound to region ‘eu-west-1’# and called with LWP# and gets it’s credentials from some custom source

Calling a method

$ec2->Method1( Param1 => ‘Something’, Param2 => 42, Complex1 => { x => 1, y => 2, z => 3 }, Complex2 => [ { x => 1, y => 2 }, { x => 2, y => 3 } ])

Calling a method

$ec2->Method1( Param1 => ‘Something’, Param2 => 42, Complex1 => { x => 1, y => 2, z => 3 }, Complex2 => [ { x => 1, y => 2 }, { x => 2, y => 3 } ])

Docs tell you that this is a Paws::Service::XXX object, but you don’t have to instance it !!!

Just pass the attributes and the values as a hashref

Calling a method: maps• Arbitrary key/value pairs• Don’t build an object either. Paws will handle it for you• $ec2->Method1( Map1 => { x => 1, y => 2, z => 3 });

Methods return objectsmy $object = $x->Method1(…)

Method1 returns Paws::Service::Method1Result has ‘X’, has ‘Y’, has ‘Complex’ => (isa => ‘Paws::Service::Complex1’)

$object->X$object->Complex->Complex1Attribute

Tricks

Tricks: Preloading classesIf you fork, and you do this in every child: my $ec2 = Paws->service(‘EC2’) $ec2->RunInstances(…)Memory for classes gets consumed in each child process

Paws->preload(‘EC2’) loads ALL EC2 classes. Paws->preload(‘EC2’, ‘RunInstances’)loads classes only for $ec2->RunInstances(…)

https://github.com/pplu/aws-sdk-perl/blob/master/examples/preload.pl

Tricks: Immutabilizing classes• Paws has lots of classes for representing lots of things• They are not (Moose) immutable (thinking that in short lived

scripts immutability makes them slower)

Paws->default_config->immutable(1);Just after use Paws;

https://github.com/pplu/aws-sdk-perl/blob/master/examples/mutability.pl

Tricks: CLI• Paws ships with a CLI

paws SERVICE --region xx-east-1 DescribeFoo Arg1 Val1

Uses ARGV::Struct to convey nested datastructures via command line

Tricks: ARGV::Structpaws SVC HashProperty { K1 V1 K2 V2 } …

paws SVC ArrayProperty [ 1 2 3 4 ] …

Tricks: open_aws_console• Opens a browser with the AWS console (using the SignIn

service)• Uses your current credentials (extends a temporary

token)

Tricks: Changing endpointsmy $predictor = $paws->service('ML', region_rules => [ { uri => $endpoint_url } ]);

• Works for any service: SQS, EC2…

Tricks: Credential providers• Default one tries to behave like AWS SDKs• Environment (AWS_ACCESS_KEY_ID and

AWS_SECRET_ACCESS_KEY)• File (~/.aws/credentials, an ini file)• From the metadata service (Instance Roles)

• Your own• Just attach Role “Paws::Credential” to a class, and get

the credentials from wherever

Tricks: Using RolesIf you’re running on an instance in AWS*:

use Paws;my $ec2 = Paws->service(‘EC2’, region => ‘eu-west-1’);$ec2->DescribeInstances;

Just works! Look ma! No credentials!

* With an Instance Role (or Instance Profile)

Hot newsNew License: Apache 2.0

Future

Future (hint: help needed and accepted)• Testing Async stuff• Retrying

• Some APIs return temporary failures• Want automatic exponential backoff with jitter -> This is in the works on retry branch

• Paging• Some APIs return paged results

• Want a “give me all of them” This is in the works on a fix-iterators branch• Waiters

• Wait until some condition is met• Want a call to wait until Instance is in running state

• A lot more: take a look at GitHub issues

Future: Waiters• Wait until some condition is met

• Wait until a DynamoDB table is readyWait until an instance is running

• Waiters are specified in jmespath format in metadata• I want jmespath implemented in Perl. See jmespath.org• Lets implement jmespath in Perl!

Future: DynamoDB as a Document storeA Put Requires this

{ ‘A key’ => { ‘S’ => ‘A string’ }, ‘Another Key’ => { ‘N’ => 123 }, ‘A String array’ => { ‘SS’ => [ ‘String1’, ‘String2’ ] } }

A document is more like this

{ ‘A key’ => ‘A string’, ‘Another Key’ => 123, ‘A String array’ => [ ‘String1’, ‘String2’ ]}

So lets convert them for the user: Issue #41 is for the taking

Future (hint: help needed and accepted)• Object Oriented results• $ec2->TerminateInstances(InstanceIds => [ ‘i-

12345678’ ])• $instance->Terminate

• Special properties• En/Decode base64, URIescape, etc

• Better access to ArrayRef and HashRef like properties• Use Array and Hash Moose trait for

• Number of elements• Get element i• Get list of elements, get list of keys

Future (hint: help needed and accepted)• Refactoring generator clases• MooseX::DataModel• Template::Toolkit

• Split Paws into separately instalable modules

• Rinse and Repeat• For other APIs• AWS API as a Service

Support for APIs

REST Plain05

101520253035404550

Types of APIs

Query+XML JSON EC2

Support for APIs

REST Plain05

101520253035404550

Types of APIs

Query+XML JSON EC2

Implemented

Support for APIs

REST Plain05

101520253035404550

Types of APIs

Query+XML JSON EC2

Implemented

Need love and testing

S3 not workingRoute53?Lambda?

…

If you want to contribute

Paws is autogenerated• AWS has some JSON definition files in their SDKs (data-driven)

• Pick them up to generate classes for:• Actions• Inputs to actions (parameters)• Outputs from actions (outputs)

• HTML documentation -> POD

make gen-classes

Code generators• In builder-lib (not distributed on CPAN)• Paws::API::Builder• Paws::API::Builder::EC2• Paws::API::Builder::query• Paws::API::Builder::json• Paws::API::Builder::restjson• Paws::API::Builder::restxml

• Leaves all auto-generated code in auto-lib (distributed on CPAN)• Hand-written code is in lib

Go build!

Fork your heart outhttps://github.com/pplu/aws-sdk-perl/

Contact me:Twitter: @pplu_ioMail: joseluis.martinez@capside.comCPAN: JLMARTIN

CAPSiDETwitter: @capsideMail: hello@capside.com