[ms_rest_azure] Introduce support for acquiring token from Managed Service Identity

.travis.yml

@@ -12,9 +12,9 @@ matrix:
     - rvm: 2.3.0
       env: LATEST_RUNTIME=true
 before_install:
+  - gem install bundler -v 1.14.1
   - if [ "$LATEST_RUNTIME" == "true" ] ; then ./scripts/latest_runtime.sh ; fi
 script:
-  - gem install bundler
   - if [ "$INTEG_RECORDED" == "true" ] ; then bundle install --gemfile=Gemfile && bundle exec rake arm:spec ; fi
   - bundle exec rake arm:build
   - unset BUNDLE_GEMFILE

Gemfile

@@ -53,3 +53,4 @@ gem 'azure_mgmt_subscriptions',             path: 'management/azure_mgmt_subscri
 gem 'azure_mgmt_traffic_manager',           path: 'management/azure_mgmt_traffic_manager'
 gem 'azure_mgmt_web',                       path: 'management/azure_mgmt_web'
 gem 'azure_sdk',                            path: 'azure_sdk'
+gem 'azure-core',                           git: 'https://github.com/katmsft/azure-ruby-asm-core.git', branch: 'master'

azure_sdk/azure_sdk.gemspec

@@ -70,5 +70,5 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency 'azure_mgmt_subscriptions', "~>#{version}"
   spec.add_runtime_dependency 'azure_mgmt_traffic_manager', "~>#{version}"
   spec.add_runtime_dependency 'azure_mgmt_web', "~>#{version}"
-  spec.add_runtime_dependency 'azure-storage', "~>0.12.1.preview"
+  spec.add_runtime_dependency 'azure-storage', "~>0.12.3.preview"
 end

runtime/ms_rest_azure/lib/ms_rest_azure.rb

@@ -11,6 +11,7 @@
 require 'ms_rest_azure/azure_service_client.rb'
 require 'ms_rest_azure/cloud_error_data.rb'
 require 'ms_rest_azure/credentials/application_token_provider.rb'
+require 'ms_rest_azure/credentials/msi_token_provider.rb'
 require 'ms_rest_azure/polling_state.rb'
 require 'ms_rest_azure/sub_resource.rb'
 require 'ms_rest_azure/resource.rb'

runtime/ms_rest_azure/lib/ms_rest_azure/credentials/application_token_provider.rb

@@ -45,7 +45,7 @@ class ApplicationTokenProvider < MsRest::TokenProvider
     # @param tenant_id [String] tenant id (also known as domain).
     # @param client_id [String] client id.
     # @param client_secret [String] client secret.
-    # @param settings [ActiveDirectoryServiceSettings] client secret.
+    # @param settings [ActiveDirectoryServiceSettings] active directory setting.
     def initialize(tenant_id, client_id, client_secret, settings = ActiveDirectoryServiceSettings.get_azure_settings)
       fail ArgumentError, 'Tenant id cannot be nil' if tenant_id.nil?
       fail ArgumentError, 'Client id cannot be nil' if client_id.nil?
@@ -81,7 +81,7 @@ def token_expired
     end
 
     #
-    # Retrieves a new authenticaion token.
+    # Retrieves a new authentication token.
     #
     # @return [String] new authentication token.
     def acquire_token

runtime/ms_rest_azure/lib/ms_rest_azure/credentials/msi_token_provider.rb

@@ -0,0 +1,112 @@
+# encoding: utf-8
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See License.txt in the project root for license information.
+
+module MsRestAzure
+  #
+  # Class that provides access to authentication token via Managed Service Identity.
+  #
+  class MSITokenProvider < MsRest::TokenProvider
+
+    private
+
+    TOKEN_ACQUIRE_URL = 'http://localhost:{port}/oauth2/token'
+    REQUEST_BODY_PATTERN = 'authority={authentication_endpoint}{tenant_id}&resource={resource_uri}'
+    DEFAULT_SCHEME = 'Bearer'
+
+    # @return [MSIActiveDirectoryServiceSettings] settings.
+    attr_accessor :settings
+
+    # @return [String] tenant id (also known as domain).
+    attr_accessor :tenant_id
+
+    # @return [Integer] port number where MSI service is running.
+    attr_accessor :port
+
+    # @return [String] auth token.
+    attr_accessor :token
+
+    # @return [Time] the date when the current token expires.
+    attr_accessor :token_expires_on
+
+    # @return [Integer] the amount of time we refresh token before it expires.
+    attr_reader :expiration_threshold
+
+    # @return [String] the type of token.
+    attr_reader :token_type
+
+    public
+
+    #
+    # Creates and initialize new instance of the MSITokenProvider class.
+    # @param tenant_id [String] tenant id (also known as domain).
+    # @param port [Integer] port number where MSI service is running.
+    # @param settings [ActiveDirectoryServiceSettings] active directory setting.
+    def initialize(tenant_id, port = 50342, settings = ActiveDirectoryServiceSettings.get_azure_settings)
+      fail ArgumentError, 'Tenant id cannot be nil' if tenant_id.nil?
+      fail ArgumentError, 'Port cannot be nil' if port.nil?
+      fail ArgumentError, 'Port must be an Integer' unless port.is_a? Integer
+      fail ArgumentError, 'Azure AD settings cannot be nil' if settings.nil?
+
+      @tenant_id = tenant_id
+      @port = port
+      @settings = settings
+
+      @expiration_threshold = 5 * 60
+    end
+
+    #
+    # Returns the string value which needs to be attached
+    # to HTTP request header in order to be authorized.
+    #
+    # @return [String] authentication headers.
+    def get_authentication_header
+      acquire_token if token_expired
+      "#{token_type} #{token}"
+    end
+
+    private
+
+    #
+    # Checks whether token is about to expire.
+    #
+    # @return [Bool] True if token is about to expire, false otherwise.
+    def token_expired
+      @token.nil? || Time.now >= @token_expires_on + expiration_threshold
+    end
+
+    #
+    # Retrieves a new authentication token.
+    #
+    # @return [String] new authentication token.
+    def acquire_token
+      token_acquire_url = TOKEN_ACQUIRE_URL.dup
+      token_acquire_url['{port}'] = @port.to_s
+
+      url = URI.parse(token_acquire_url)
+
+      connection = Faraday.new(:url => url, :ssl => MsRest.ssl_options) do |builder|
+        builder.adapter Faraday.default_adapter
+      end
+
+      request_body = REQUEST_BODY_PATTERN.dup
+      request_body['{authentication_endpoint}'] = ERB::Util.url_encode(@settings.authentication_endpoint)
+      request_body['{tenant_id}'] = ERB::Util.url_encode(@tenant_id)
+      request_body['{resource_uri}'] = ERB::Util.url_encode(@settings.token_audience)
+
+      response = connection.post do |request|
+        request.headers['content-type'] = 'application/x-www-form-urlencoded'
+        request.body = request_body
+      end
+
+      fail AzureOperationError,
+        'Couldn\'t acquire access token from Managed Service Identity, please verify your tenant id, port and settings' unless response.status == 200
+
+      response_body = JSON.load(response.body)
+      @token = response_body['access_token']
+      @token_expires_on = Time.at(Integer(response_body['expires_on']))
+      @token_type = response_body['token_type']
+    end
+  end
+
+end

runtime/ms_rest_azure/spec/msi_token_provider_spec.rb

@@ -0,0 +1,46 @@
+# encoding: utf-8
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See License.txt in the project root for license information.
+
+require 'rspec'
+require 'ms_rest_azure'
+
+module MsRestAzure
+
+  describe MSITokenProvider do
+    it 'should throw error if nil data is passed into constructor' do
+      expect { MSITokenProvider.new(nil) }.to raise_error(ArgumentError)
+      expect { MSITokenProvider.new('tenant_id',nil) }.to raise_error(ArgumentError)
+      expect { MSITokenProvider.new('tenant_id','port') }.to raise_error(ArgumentError)
+      expect { MSITokenProvider.new('tenant_id',50431,nil) }.to raise_error(ArgumentError)
+    end
+
+    it 'should set defaults for managed service identity' do
+      tenant = 'xxxx-xxxx-xxxxx-xxxxx'
+      azure_cloud = MsRestAzure::AzureEnvironments::AzureCloud
+
+      token_provider = MSITokenProvider.new(tenant)
+      expect(token_provider.send(:tenant_id)).to eq(tenant)
+      expect(token_provider.send(:port)).to eq(50342)
+      settings = token_provider.send(:settings)
+      expect(settings.authentication_endpoint).to eq(azure_cloud.active_directory_endpoint_url)
+      expect(settings.token_audience).to eq(azure_cloud.active_directory_resource_id)
+    end
+
+    it 'should set customs for managed service identity' do
+      tenant = 'xxxx-xxxx-xxxxx-xxxxx'
+      port = 50333
+      settings = ActiveDirectoryServiceSettings.new()
+      settings.authentication_endpoint = 'https://login.microsoftonline.com/'
+      settings.token_audience = 'https://vault.azure.net'
+
+      token_provider = MSITokenProvider.new(tenant, port, settings)
+      expect(token_provider.send(:tenant_id)).to eq(tenant)
+      expect(token_provider.send(:port)).to eq(port)
+      settings = token_provider.send(:settings)
+      expect(settings.authentication_endpoint).to eq(settings.authentication_endpoint)
+      expect(settings.token_audience).to eq(settings.token_audience)
+    end
+  end
+
+end