Fixes #27418 - Support docker pull with pulp3

This supports docker pull with pulp3. Crane (pulp2) is still supported and the
registry URL is dynamically determined based on the support for Docker blobs.

Previously, the RegistryResource class would run code when loaded, setting up
the inherited class variables. This commit moves this and the new logic to a class
method. Since there are now backend calls (to check for pulp3) to set up the class
variables, it seems like this should be a more deliberate action. This also makes testing
much easier.

I'm open to other suggestions on how to handle the class inheritance and the class variables.

To test:
- Modify foreman/config/settings.plugins.d/katello.yaml, adding the pulp_registry_url
```yaml
  :container_image_registry:
    :crane_url: https://localhost:5000
    :pulp_registry_url: http://localhost:24816
    :registry_ca_cert_file: /etc/pki/katello/certs/katello-default-ca.crt
```
- Set up docker on pulp3 box. You will need an up-to-date box since pulp/pulp_docker#391 was merged
- Sync repos, you can use https://cloud.docker.com/u/jomitsch/repository/docker/jomitsch/workflow-test for a small one.
- docker login $HOSTNAME
- docker pull $HOSTNAME/default_organization-docker-workflow_test (check name in docker repo details)
- docker pull should be successful

It's worth trying out some other repos or registries (like quay.io) and also we should ensure pulp2 functionality is not expected

There will be installer changes to come that will update both dev and prod's katello.yml, these will need to be merged along
with this PR

I also updated the rubocop_todo as it was throwing warnings for duplicate entries.

.rubocop_todo.yml

@@ -122,13 +122,6 @@ Metrics/ClassLength:
 Metrics/CyclomaticComplexity:
   Max: 14
 
-# Offense count: 875
-# Cop supports --auto-correct.
-# Configuration parameters: AutoCorrect, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
-# URISchemes: http, https
-Metrics/LineLength:
-  Max: 200
-
 # Offense count: 23
 # Configuration parameters: CountComments.
 Metrics/ModuleLength:

app/lib/katello/resources/registry.rb

@@ -12,22 +12,38 @@ def self.logger
 
         def self.get(path, headers = {:accept => :json})
           logger.debug "Sending GET request to Registry: #{path}"
-          client = RegistryResource.rest_client(Net::HTTP::Get, :get, path)
+          client = RegistryResource.load_class.rest_client(Net::HTTP::Get, :get, path)
           client.get(headers)
         end
       end
 
       class RegistryResource < HttpResource
-        if SETTINGS[:katello][:container_image_registry]
-          cfg = SETTINGS[:katello][:container_image_registry]
-          url = cfg[:crane_url]
-          uri = URI.parse(url)
-          self.prefix = uri.path
-          self.site = "#{uri.scheme}://#{uri.host}:#{uri.port}"
-          self.ca_cert_file = cfg[:crane_ca_cert_file]
-        end
+        extend Concerns::SmartProxyExtensions
 
         class << self
+          def load_class
+            container_config = SETTINGS.dig(:katello, :container_image_registry)
+            registry_url = nil
+
+            if container_config
+              crane_url = container_config[:crane_url]
+              pulp_registry_url = container_config[:pulp_registry_url]
+              registry_url = crane_url if crane_url
+              # pulp 3 acts as its own registry
+              if pulp_registry_url && content_pulp3_support?(::Katello::DockerBlob::CONTENT_TYPE)
+                registry_url = pulp_registry_url
+              end
+            end
+
+            logger.send(:error, "No container registry url specified") unless registry_url
+
+            uri = URI.parse(registry_url)
+            self.prefix = uri.path
+            self.site = "#{uri.scheme}://#{uri.host}:#{uri.port}"
+            self.ca_cert_file = container_config[:registry_ca_cert_file]
+            self
+          end
+
           def process_response(response)
             debug_level = response.code >= 400 ? :error : :debug
             logger.send(debug_level, "Registry request returned with code #{response.code}")

test/lib/resources/registry_test.rb

@@ -0,0 +1,26 @@
+require 'katello_test_helper'
+
+module Katello
+  module Resources
+    class RegistryTest < ActiveSupport::TestCase
+      before do
+        SETTINGS[:katello][:container_image_registry] = {
+          crane_url: "https://localhost:5000",
+          pulp_registry_url: "http://localhost:24816"
+        }
+      end
+
+      def test_pulp3_registry_url
+        Registry::RegistryResource.expects(:content_pulp3_support?).returns(true)
+        pulp_registry_url = SETTINGS[:katello][:container_image_registry][:pulp_registry_url]
+        assert_equal Registry::RegistryResource.load_class.site, pulp_registry_url
+      end
+
+      def test_crane_registry_url
+        Registry::RegistryResource.expects(:content_pulp3_support?).returns(false)
+        crane_url = SETTINGS[:katello][:container_image_registry][:crane_url]
+        assert_equal Registry::RegistryResource.load_class.site, crane_url
+      end
+    end
+  end
+end