Add support for custom domains to the internal Pages API

Update the `/internal/pages` endpoint to return virtual domain
configuration for custom domains.

app/models/pages/lookup_path.rb

+# frozen_string_literal: true
+
+module Pages
+  class LookupPath
+    def initialize(project, domain: nil)
+      @project = project
+      @domain = domain
+    end
+
+    def project_id
+      project.id
+    end
+
+    def access_control
+      project.private_pages?
+    end
+
+    def https_only
+      domain_https = domain ? domain.https? : true
+      project.pages_https_only? && domain_https
+    end
+
+    def source
+      {
+        type: 'file',
+        path: File.join(project.full_path, 'public/')
+      }
+    end
+
+    def prefix
+      '/'
+    end
+
+    private
+
+    attr_reader :project, :domain
+  end
+end

app/models/pages/virtual_domain.rb

+# frozen_string_literal: true
+
+module Pages
+  class VirtualDomain
+    def initialize(projects, domain: nil)
+      @projects = projects
+      @domain = domain
+    end
+
+    def certificate
+      domain&.certificate
+    end
+
+    def key
+      domain&.key
+    end
+
+    def lookup_paths
+      projects.map do |project|
+        project.pages_lookup_path(domain: domain)
+      end.sort_by(&:prefix).reverse
+    end
+
+    private
+
+    attr_reader :projects, :domain
+  end
+end

app/models/pages_domain.rb

@@ -185,6 +185,10 @@ class PagesDomain < ApplicationRecord
     self.certificate_source = 'gitlab_provided' if key_changed?
   end
+  def pages_virtual_domain
+    Pages::VirtualDomain.new([project], domain: self)
+  end
+
   private
   def set_verification_code

app/models/project.rb

@@ -61,11 +61,11 @@ class Project < ApplicationRecord
   cache_markdown_field :description, pipeline: :description
-  delegate :feature_available?, :builds_enabled?, :wiki_enabled?,
-           :merge_requests_enabled?, :issues_enabled?, :pages_enabled?, :public_pages?,
-           :merge_requests_access_level, :issues_access_level, :wiki_access_level,
-           :snippets_access_level, :builds_access_level, :repository_access_level,
-           to: :project_feature, allow_nil: true
+  delegate :feature_available?, :builds_enabled?, :wiki_enabled?, :merge_requests_enabled?,
+    :issues_enabled?, :pages_enabled?, :public_pages?, :private_pages?,
+    :merge_requests_access_level, :issues_access_level, :wiki_access_level,
+    :snippets_access_level, :builds_access_level, :repository_access_level,
+    to: :project_feature, allow_nil: true
   delegate :base_dir, :disk_path, :ensure_storage_path_exists, to: :storage
@@ -2201,6 +2201,10 @@ class Project < ApplicationRecord
     members.maintainers.order_recent_sign_in.limit(ACCESS_REQUEST_APPROVERS_TO_BE_NOTIFIED_LIMIT)
   end
+  def pages_lookup_path(domain: nil)
+    Pages::LookupPath.new(self, domain: domain)
+  end
+
   private
   def merge_requests_allowing_collaboration(source_branch = nil)

app/models/project_feature.rb

@@ -129,6 +129,10 @@ class ProjectFeature < ApplicationRecord
     pages_access_level == PUBLIC || pages_access_level == ENABLED && project.public?
   end
+  def private_pages?
+    !public_pages?
+  end
+
   private
   # Validates builds and merge requests access level

lib/api/entities/internal.rb

+# frozen_string_literal: true
+
+module API
+  module Entities
+    module Internal
+      module Pages
+        class LookupPath < Grape::Entity
+          expose :project_id, :access_control,
+            :source, :https_only, :prefix
+        end
+
+        class VirtualDomain < Grape::Entity
+          expose :certificate, :key
+          expose :lookup_paths, using: LookupPath
+        end
+      end
+    end
+  end
+end

lib/api/internal/pages.rb

@@ -18,7 +18,12 @@ module API
       namespace 'internal' do
         namespace 'pages' do
           get "/" do
-            status :ok
+            host = PagesDomain.find_by_domain(params[:host])
+            not_found! unless host
+
+            virtual_domain = host.pages_virtual_domain
+
+            present virtual_domain, with: Entities::Internal::Pages::VirtualDomain
           end
         end
       end

spec/fixtures/api/schemas/internal/pages/lookup_path.json

+{
+  "type": "object",
+  "required": [
+    "project_id",
+    "https_only",
+    "access_control",
+    "source",
+    "prefix"
+  ],
+  "properties": {
+    "project_id": { "type": "integer" },
+    "https_only": { "type": "boolean" },
+    "access_control": { "type": "boolean" },
+    "source": { "type": "object",
+      "required": ["type", "path"],
+      "properties" : {
+        "type": { "type": "string", "enum": ["file"] },
+        "path": { "type": "string" }
+      },
+      "additionalProperties": false
+    },
+    "prefix": { "type": "string" }
+  },
+  "additionalProperties": false
+}

spec/fixtures/api/schemas/internal/pages/virtual_domain.json

+{
+  "type": "object",
+  "required": [
+    "lookup_paths"
+  ],
+  "optional": [
+    "certificate",
+    "key"
+  ],
+  "properties": {
+    "certificate": { "type": ["string", "null"] },
+    "key": { "type": ["string", "null"] },
+    "lookup_paths": { "type": "array", "items": { "$ref": "lookup_path.json" } }
+  },
+  "additionalProperties": false
+}

spec/models/pages/lookup_path_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Pages::LookupPath do
+  let(:project) do
+    instance_double(Project,
+      id: 12345,
+      private_pages?: true,
+      pages_https_only?: true,
+      full_path: 'the/full/path'
+    )
+  end
+
+  subject(:lookup_path) { described_class.new(project) }
+
+  describe '#project_id' do
+    it 'delegates to Project#id' do
+      expect(lookup_path.project_id).to eq(12345)
+    end
+  end
+
+  describe '#access_control' do
+    it 'delegates to Project#private_pages?' do
+      expect(lookup_path.access_control).to eq(true)
+    end
+  end
+
+  describe '#https_only' do
+    subject(:lookup_path) { described_class.new(project, domain: domain) }
+
+    context 'when no domain provided' do
+      let(:domain) { nil }
+
+      it 'delegates to Project#pages_https_only?' do
+        expect(lookup_path.https_only).to eq(true)
+      end
+    end
+
+    context 'when there is domain provided' do
+      let(:domain) { instance_double(PagesDomain, https?: false) }
+
+      it 'takes into account the https setting of the domain' do
+        expect(lookup_path.https_only).to eq(false)
+      end
+    end
+  end
+
+  describe '#source' do
+    it 'sets the source type to "file"' do
+      expect(lookup_path.source[:type]).to eq('file')
+    end
+
+    it 'sets the source path to the project full path suffixed with "public/' do
+      expect(lookup_path.source[:path]).to eq('the/full/path/public/')
+    end
+  end
+
+  describe '#prefix' do
+    it 'returns "/"' do
+      expect(lookup_path.prefix).to eq('/')
+    end
+  end
+end

spec/requests/api/internal/pages_spec.rb

@@ -43,10 +43,32 @@ describe API::Internal::Pages do
           super(host, headers)
         end
-        it 'responds with 200 OK' do
-          query_host('pages.gitlab.io')
-          expect(response).to have_gitlab_http_status(200)
+        context 'not existing host' do
+          it 'responds with 404 Not Found' do
+            query_host('pages.gitlab.io')
+
+            expect(response).to have_gitlab_http_status(404)
+          end
+        end
+
+        context 'custom domain' do
+          let(:namespace) { create(:namespace, name: 'gitlab-org') }
+          let(:project) { create(:project, namespace: namespace, name: 'gitlab-ce') }
+          let!(:pages_domain) { create(:pages_domain, domain: 'pages.gitlab.io', project: project) }
+
+          it 'responds with the correct domain configuration' do
+            query_host('pages.gitlab.io')
+
+            expect(response).to have_gitlab_http_status(200)
+            expect(response).to match_response_schema('internal/pages/virtual_domain')
+
+            expect(json_response['certificate']).to eq(pages_domain.certificate)
+            expect(json_response['key']).to eq(pages_domain.key)
+            lookup_path = json_response['lookup_paths'][0]
+            expect(lookup_path['prefix']).to eq('/')
+            expect(lookup_path['source']['path']).to eq('gitlab-org/gitlab-ce/public/')
+          end
         end
       end
     end