Move @sha256 part to the image path for Docker LRP rootfs (cloudfoundry#3889)

Co-authored-by: Nicolas Bender <[email protected]>

Author: pbusko

lib/cloud_controller/diego/docker/docker_uri_converter.rb

@@ -6,6 +6,12 @@ def convert(docker_uri)
       raise UriUtils::InvalidDockerURI.new "Docker URI [#{docker_uri}] should not contain scheme" if docker_uri.include? '://'
 
       host, path, tag = UriUtils.parse_docker_uri(docker_uri)
+
+      if !tag.nil? && tag.start_with?('@sha256:')
+        path = "#{path}@sha256"
+        tag.slice!('@sha256:')
+      end
+
       Addressable::URI.new(scheme: 'docker', host: host, path: path, fragment: tag).to_s
     end
   end

spec/unit/lib/cloud_controller/diego/docker/docker_uri_converter_spec.rb

@@ -38,6 +38,14 @@ module VCAP::CloudController
           expect(converter.convert(image_url)).to eq('docker:///user/image#tag')
         end
       end
+
+      context('and a user/image@sha256:9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08') do
+        let(:image_url) { 'user/image@sha256:9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08' }
+
+        it 'builds the correct rootFS path' do
+          expect(converter.convert(image_url)).to eq('docker:///user/image@sha256#9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08')
+        end
+      end
     end
 
     context('and the docker image url has host:port') do