[PoC] Implement Custom Stacks RFC

Allow to patch stacks descriptions

Author: FloThinksPi

app/actions/stack_update.rb

@@ -9,6 +9,7 @@ def initialize
 
     def update(stack, message)
       stack.db.transaction do
+        stack.update(description: message.description) if message.requested?(:description)
         MetadataUpdate.update(stack, message)
       end
       @logger.info("Finished updating metadata on stack #{stack.guid}")

app/messages/app_manifest_message.rb

@@ -104,7 +104,7 @@ def sidecar_create_messages
     end
 
     def app_update_message
-      @app_update_message ||= AppUpdateMessage.new(app_lifecycle_hash)
+      @app_update_message ||= AppUpdateMessage.new(lifecycle: lifecycle_message)
     end
 
     def app_update_environment_variables_message

app/messages/buildpack_lifecycle_data_message.rb

@@ -40,7 +40,14 @@ def buildpacks_content
     def credentials_content
       return unless credentials.is_a?(Hash)
 
-      errors.add(:credentials, 'credentials value must be a hash') if credentials.any? { |_, v| !v.is_a?(Hash) }
+      credentials.each do |registry, creds|
+        unless creds.is_a?(Hash)
+          errors.add(:credentials, "for registry '#{registry}' must be a hash")
+          next
+        end
+
+        errors.add(:credentials, "for registry '#{registry}' must include 'username' and 'password'") unless creds.key?('username') && creds.key?('password')
+      end
     end
   end
 end

app/messages/stack_update_message.rb

@@ -2,8 +2,9 @@
 
 module VCAP::CloudController
   class StackUpdateMessage < MetadataBaseMessage
-    register_allowed_keys []
+    register_allowed_keys %i[description]
 
+    validates :description, length: { maximum: 250 }
     validates_with NoAdditionalKeysValidator
   end
 end

app/models/runtime/feature_flag.rb

@@ -14,6 +14,7 @@ class UndefinedFeatureFlagError < StandardError
       service_instance_creation: true,
       diego_docker: false,
       diego_cnb: false,
+      diego_custom_stacks: false,
       set_roles_by_username: true,
       unset_roles_by_username: true,
       task_creation: true,

lib/cloud_controller/diego/lifecycles/buildpack_lifecycle_data_validator.rb

@@ -8,6 +8,14 @@ class BuildpackLifecycleDataValidator
 
     validate :buildpacks_are_uri_or_nil
     validate :stack_exists_in_db
+    validate :custom_stack_requires_custom_buildpack
+
+    def custom_stack_requires_custom_buildpack
+      return unless stack.is_a?(String) && stack.include?('docker://')
+      return if buildpack_infos.all?(&:custom?)
+
+      errors.add(:buildpack, 'must be a custom buildpack when using a custom stack')
+    end
 
     def buildpacks_are_uri_or_nil
       buildpack_infos.each do |buildpack_info|
@@ -24,7 +32,11 @@ def buildpacks_are_uri_or_nil
     end
 
     def stack_exists_in_db
-      errors.add(:stack, 'must be an existing stack') if stack.nil?
+      return if stack.nil?
+      return if stack.is_a?(String) && stack.include?('docker://') && FeatureFlag.enabled?(:diego_custom_stacks)
+      return if VCAP::CloudController::Stack.where(name: stack).any?
+
+      errors.add(:stack, 'must be an existing stack')
     end
   end
 end

lib/cloud_controller/diego/lifecycles/lifecycle_base.rb

@@ -17,7 +17,13 @@ def initialize(package, staging_message)
     delegate :valid?, :errors, to: :validator
 
     def staging_stack
-      requested_stack || app_stack || VCAP::CloudController::Stack.default.name
+      stack = requested_stack || app_stack || VCAP::CloudController::Stack.default.name
+      FeatureFlag.raise_unless_enabled!(:diego_custom_stacks) if stack.is_a?(String) && stack.include?('docker://')
+      stack
+    end
+
+    def credentials
+      staging_message.lifecycle_data[:credentials]
     end
 
     private

lib/cloud_controller/diego/task_recipe_builder.rb

@@ -91,12 +91,36 @@ def build_staging_task(config, staging_details)
               "app:#{staging_details.package.app_guid}"
             ]
           ),
-          image_username: staging_details.package.docker_username,
-          image_password: staging_details.package.docker_password,
+          image_username: image_username(staging_details),
+          image_password: image_password(staging_details),
           volume_mounted_files: ServiceBindingFilesBuilder.build(staging_details.package.app)
         }.compact)
       end
 
+      def image_username(staging_details)
+        return staging_details.package.docker_username if staging_details.package.docker_username.present?
+        return unless staging_details.lifecycle.respond_to?(:credentials) && staging_details.lifecycle.credentials.present?
+
+        cred = get_credentials_for_stack(staging_details)
+        cred ? cred['user'] : nil
+      end
+
+      def image_password(staging_details)
+        return staging_details.package.docker_password if staging_details.package.docker_password.present?
+        return unless staging_details.lifecycle.respond_to?(:credentials) && staging_details.lifecycle.credentials.present?
+
+        cred = get_credentials_for_stack(staging_details)
+        cred ? cred['password'] : nil
+      end
+
+      def get_credentials_for_stack(staging_details)
+        return nil unless staging_details.lifecycle.staging_stack.include?('docker://')
+
+        stack_uri = URI.parse(staging_details.lifecycle.staging_stack)
+        host = stack_uri.host
+        staging_details.lifecycle.credentials[host]
+      end
+
       private
 
       def metric_tags(source)

spec/api/documentation/feature_flags_api_spec.rb

@@ -18,7 +18,7 @@
       client.get '/v2/config/feature_flags', {}, headers
 
       expect(status).to eq(200)
-      expect(parsed_response.length).to eq(18)
+      expect(parsed_response.length).to eq(19)
       expect(parsed_response).to include(
         {
           'name' => 'user_org_creation',

spec/unit/actions/app_update_spec.rb

@@ -259,6 +259,40 @@ module VCAP::CloudController
           end
         end
 
+        context 'when the lifecycle is valid' do
+          let(:message) do
+            AppUpdateMessage.new({
+                                   lifecycle: {
+                                     type: 'buildpack',
+                                     data: { buildpacks: ['http://new-buildpack.url', 'ruby'], stack: stack.name }
+                                   }
+                                 })
+          end
+
+          it 'does not raise an error' do
+            expect do
+              app_update.update(app_model, message, lifecycle)
+            end.not_to raise_error
+          end
+        end
+
+        context 'when the lifecycle is valid' do
+          let(:message) do
+            AppUpdateMessage.new({
+                                   lifecycle: {
+                                     type: 'buildpack',
+                                     data: { buildpacks: ['http://new-buildpack.url', 'ruby'], stack: stack.name }
+                                   }
+                                 })
+          end
+
+          it 'does not raise an error' do
+            expect do
+              app_update.update(app_model, message, lifecycle)
+            end.not_to raise_error
+          end
+        end
+
         context 'when changing the lifecycle type' do
           let(:message) do
             AppUpdateMessage.new({