How can we map identifier (service) against their associated class names?

[stonefield]

We use the service in the arn to map it to an associated client in the SDK.
After autoloading was implemented in the SDK, we are not able to do so, but maybe a solution exists en I haven't found it?

An example of how we do this:

    arn = "arn:aws:ec2:eu-west-1:123456789012:i-1234abcde"
    Boar::Aws::Service.new(arn)
    => instance of Aws::EC2::Client

Here is an example of how we implemented this. It worked with version 3.203.

    module Boar
      module AWS
        class Service
          class << self

            def client(resource_arn)
              new(resource_arn).client
            end

            def client_for(service)
              unless services[service]
                load_services
              end
              client = services[service]
              raise ServiceNotLoaded, "The service for #{service} has not been loaded." unless client
              client
            end

            def services
              @@services ||= {}.with_indifferent_access
            end

            def load_services
              Seahorse::Client::Base.descendants.each do |klass|
                if klass.respond_to? :identifier
                  services[klass.identifier] = klass
                end
              end
            end
          end

          attr_reader :arn

          def initialize(resource_arn)
            @arn = Aws::ARN.parse(resource_arn)
          end

          def client
            @client ||= begin
              arguments = {region: arn.region}
              arguments.merge!(credentials: Boar.credentials[arn.account_id]) if Boar.credentials[arn.account_id]
              self.class.client_for(arn.service).new(arguments)
            end
          end

          def tags
            TagsReader.new(client, arn.to_s).read
          end
        end
      end
    end

Provided that the gems aws-sdk-iam and aws-sdk-ec2 were included, Boar::Aws::Service.services would contain a hash such as:

{sts: Aws::STS::Client, iam: Aws::IAM::Client, ec2: Aws::EC2::Client ssooidc: Aws::SSOOIDC::Client, sso: Aws::SSO::Client}

With autoloading, Seahorse::Client::Base.descendants will not work before the classes has been defined,
so our attempt to create the mapping between arn's service part and the identifier for the associated class does no longer work.

Is there another way to accommodate this mapping, or is there anything you can do to make such mapping available?

[alextwoods]

Rather than use Seahorse::Client::Base.descendants you can use the Aws namespace - something like:

def load_services
  Aws.constants.each do |c|
    m = Aws.const_get(c)
    if m.is_a?(Module) && m.const_defined?(:Client) && m.const_get(:Client).respond_to?(:identifier)
      klass = m.const_get(:Client)
      services[klass.identifier] = klass
    end
  end
end

This works with the autoload (though of course, it does trigger the loading).

[stonefield]

Thank you, @alextwoods - That works perfectly.

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