Favor sdkv2 (#57)

* Favor SDK v2

This PR does two things. The first is that in AwsShim, it changes the behavior to favor AWS SDK v2 if it's in the load path over v1. Presumably if you have both in your load path you want the most recent. The other thing that this PR does is allow you to manually specify which version of the SDK to use through the config object. That would look like:

    Humidifier.configure { |config| config.sdk_version = 1 }

* Add docs on specifying the SDK version

README.md

@@ -43,6 +43,14 @@ Once stacks have the appropriate resources, you can query AWS to handle all stac
 
 Humidifier assumes you have an `aws-sdk` gem installed when you call these operations. It detects the version of the gem you have installed and uses the appropriate API depending on what is available. If Humidifier cannot find any way to use the AWS SDK, it will warn you on every API call and simply return false.
 
+You can also manually specify the version of the SDK that you want to use, in the case that you have both gems in your load path. In that case, you would specify it on the Humidifier configuration object:
+
+```ruby
+Humidifier.configure do |config|
+  config.sdk_version = 1
+end
+```
+
 #### CloudFormation functions
 
 You can use CFN intrinsic functions and references using `Humidifier.fn.[name]` and `Humidifier.ref`. Those will build appropriate structures that know how to be dumped to CFN syntax appropriately.

lib/humidifier/aws_shim.rb

@@ -20,18 +20,17 @@ class AwsShim
 
     attr_accessor :shim
 
-    # Attempt to require both aws-sdk-v1 and aws-sdk, then set the shim based on what successfully loaded
+    # Either set the SDK based on the configured option or guess the SDK
+    # version by attempting to require both aws-sdk-v1 and aws-sdk, then setting
+    # the shim based on what successfully loaded
     def initialize
-      try_require_sdk('aws-sdk-v1')
-      try_require_sdk('aws-sdk')
-
       self.shim =
-        if Object.const_defined?(:AWS)
+        if Humidifier.config.sdk_version_1?
           AwsAdapters::SDKV1.new
-        elsif Object.const_defined?(:Aws)
+        elsif Humidifier.config.sdk_version_2?
           AwsAdapters::SDKV2.new
         else
-          AwsAdapters::Noop.new
+          guess_sdk
         end
     end
 
@@ -52,6 +51,19 @@ def shim
 
     private
 
+    def guess_sdk
+      try_require_sdk('aws-sdk-v1')
+      try_require_sdk('aws-sdk')
+
+      if Object.const_defined?(:Aws)
+        AwsAdapters::SDKV2.new
+      elsif Object.const_defined?(:AWS)
+        AwsAdapters::SDKV1.new
+      else
+        AwsAdapters::Noop.new
+      end
+    end
+
     def try_require_sdk(name)
       require name
     rescue LoadError # rubocop:disable Lint/HandleExceptions

lib/humidifier/configuration.rb

@@ -14,16 +14,27 @@ class Configuration
     end
 MSG
 
-    attr_accessor :s3_bucket, :s3_prefix
+    attr_accessor :s3_bucket, :s3_prefix, :sdk_version
 
     def initialize(opts = {})
-      self.s3_bucket = opts[:s3_bucket]
-      self.s3_prefix = opts[:s3_prefix]
+      self.s3_bucket   = opts[:s3_bucket]
+      self.s3_prefix   = opts[:s3_prefix]
+      self.sdk_version = opts[:sdk_version]
     end
 
     # raise an error unless the s3_bucket field is set
     def ensure_upload_configured!(payload)
       raise UPLOAD_MESSAGE.gsub('%{identifier}', payload.identifier) if s3_bucket.nil?
     end
+
+    # true if the sdk_version option is set to 1 or '1'
+    def sdk_version_1?
+      sdk_version.to_s == '1'
+    end
+
+    # true if the sdk_version option is set to 2 or '2'
+    def sdk_version_2?
+      sdk_version.to_s == '2'
+    end
   end
 end

lib/humidifier/version.rb

@@ -1,4 +1,4 @@
 module Humidifier
   # Gem version
-  VERSION = '0.6.1'.freeze
+  VERSION = '0.7.0'.freeze
 end

test/aws_adapters/base_test.rb

@@ -70,7 +70,7 @@ def upload_object(_, key)
       end
     end
 
-    with_config('test.s3.bucket', 'prefix/') do
+    with_config(s3_bucket: 'test.s3.bucket', s3_prefix: 'prefix/') do
       assert_equal 'prefix/name.json', fake_sdk.new.upload(payload(identifier: 'name'))
     end
   end

test/aws_adapters/sdkv1_test.rb

@@ -55,7 +55,7 @@ def test_create_and_wait_failure
   end
 
   def test_upload
-    with_config('test.s3.bucket') do
+    with_config(s3_bucket: 'test.s3.bucket') do
       with_sdk_v1_loaded do |sdk|
         upload_expectations
         sdk.upload(payload(identifier: 'identifier', to_cf: 'body'))

test/aws_adapters/sdkv2_test.rb

@@ -65,7 +65,7 @@ def test_create_and_wait
   end
 
   def test_upload
-    with_config('test.s3.bucket') do
+    with_config(s3_bucket: 'test.s3.bucket') do
       with_sdk_v2_loaded do |sdk|
         SdkSupport.expect(:config, [], SdkSupport.double)
         SdkSupport.expect(:update, [region: Humidifier::AwsShim::REGION])

test/aws_shim_test.rb

@@ -13,19 +13,30 @@ def test_forwarding
     mock.verify
   end
 
-  def test_initialize_noop
-    assert_kind_of Humidifier::AwsAdapters::Noop, Humidifier::AwsShim.new.shim
+  def test_initialize_sdk_version_1?
+    with_config(sdk_version: 1) { assert_shim(:SDKV1) }
   end
 
-  def test_initialize_sdk_v1
-    with_sdk_v1_loaded do
-      assert_kind_of Humidifier::AwsAdapters::SDKV1, Humidifier::AwsShim.new.shim
-    end
+  def test_initialize_sdk_version_2?
+    with_config(sdk_version: 2) { assert_shim(:SDKV2) }
   end
 
-  def test_initialize_sdk_v2
-    with_sdk_v2_loaded do
-      assert_kind_of Humidifier::AwsAdapters::SDKV2, Humidifier::AwsShim.new.shim
-    end
+  def test_guess_sdk_noop
+    assert_shim(:Noop)
+  end
+
+  def test_guess_sdk_sdk_v1
+    with_sdk_v1_loaded { assert_shim(:SDKV1) }
+  end
+
+  def test_guess_sdk_sdk_v2
+    with_sdk_v2_loaded { assert_shim(:SDKV2) }
+  end
+
+  private
+
+  def assert_shim(kind)
+    expected = Humidifier::AwsAdapters.const_get(kind)
+    assert_kind_of expected, Humidifier::AwsShim.new.shim
   end
 end

test/configuration_test.rb

@@ -3,17 +3,33 @@
 class ConfigurationTest < Minitest::Test
 
   def test_ensure_upload_configured!
-    config = Humidifier::Configuration.new
     error =
       assert_raises RuntimeError do
-        config.ensure_upload_configured!(payload(identifier: 'foobar'))
+        build.ensure_upload_configured!(payload(identifier: 'foobar'))
       end
     assert_match(/foobar/, error.message)
   end
 
   def test_ensure_upload_configured_passes
-    config = Humidifier::Configuration.new
-    config.s3_bucket = Object.new
+    config = build(s3_bucket: Object.new)
     config.ensure_upload_configured!(payload(identifier: 'foobar'))
   end
+
+  def test_sdk_version_1?
+    assert build(sdk_version: 1).sdk_version_1?
+    assert build(sdk_version: '1').sdk_version_1?
+    refute build(sdk_version: 'foobar').sdk_version_1?
+  end
+
+  def test_sdk_version_2?
+    assert build(sdk_version: 2).sdk_version_2?
+    assert build(sdk_version: '2').sdk_version_2?
+    refute build(sdk_version: 'foobar').sdk_version_2?
+  end
+
+  private
+
+  def build(options = {})
+    Humidifier::Configuration.new(options)
+  end
 end

test/test_helper.rb

@@ -31,8 +31,8 @@ def tracker
 
 # extra methods for testing config and serializers
 Minitest::Test.send(:include, Module.new do
-  def with_config(s3_bucket, s3_prefix = nil, &block)
-    config = Humidifier::Configuration.new(s3_bucket: s3_bucket, s3_prefix: s3_prefix)
+  def with_config(options = {}, &block)
+    config = Humidifier::Configuration.new(options)
     Humidifier.stub(:config, config, &block)
   end