Fixes #38231 - Provide fallback to simple deb publish

Co-authored-by: Markus Bucher <bucher@atix.de>

We have encountered some rare corner cases where pulp_deb repos created
using older Katello versions do not have any PRC structure content. In
such cases we fall back to simple publishing. In the future we may
replace this with a data repair migration on the pulp_deb side.

app/models/katello/repository.rb

@@ -1046,6 +1046,7 @@ def in_content_view?(content_view)
 
     def deb_content_url_options
       return '' unless version_href
+      return '' if backend_service(SmartProxy.pulp_primary).version_missing_structure_content?
 
       components = deb_pulp_components.join(',')
       distributions = deb_pulp_distributions.join(',')

app/services/katello/pulp3/repository/apt.rb

@@ -39,7 +39,7 @@ def sync_url_params(sync_options)
         end
 
         def mirror_remote_options
-          distributions = if repo.deb_using_structured_apt?
+          distributions = if repo.deb_using_structured_apt? && !version_missing_structure_content?
                             repo.deb_pulp_distributions.join(' ')
                           else
                             'default'
@@ -48,11 +48,29 @@ def mirror_remote_options
           super.merge({distributions: distributions})
         end
 
+        def version_missing_structure_content?
+          # There may be old pulp_deb repo versions that have no package_release_components to go with the packages.
+          # This could be because packages were uploaded with Katello < 4.12
+          # It may also affect filtered CV versions created with very old Katello versions.
+          # This method can identify such cases, so that we may fall back to simple publishing.
+          return false if repo.version_href.blank?
+          # We cannot just use api here, because this is sometimes the proxy api, and we always want to talk to the primary!
+          api_primary = self.class.instance_for_type(repo, ::SmartProxy.pulp_primary).api
+          version = api_primary.repository_versions_api.read(repo.version_href)
+          apt_content_types = version&.content_summary&.present&.keys
+          return apt_content_types.include?('deb.package') && !apt_content_types.include?('deb.package_release_component')
+        end
+
         def publication_options(repository)
           ss = api.signing_services_api.list(name: SIGNING_SERVICE_NAME).results
           popts = super(repository)
-          popts.merge!({ structured: true })
-          popts.merge!({ simple: true }) unless repository.deb_using_structured_apt?
+          if version_missing_structure_content?
+            popts.merge!({ structured: false })
+            popts.merge!({ simple: true })
+          else
+            popts.merge!({ structured: true })
+            popts.merge!({ simple: true }) unless repository.deb_using_structured_apt?
+          end
           popts[:signing_service] = ss[0].pulp_href if ss && ss.length == 1
           popts
         end