Allow to setup Documentation pages URL for help pages redirects

Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/32328

* Show a configuration option in Admin Area to set Documentation pages
URL
* Redirect requests to documentation pages to the host defined by
configuration option

Changelog: added

app/controllers/help_controller.rb

@@ -72,7 +72,6 @@ class HelpController < ApplicationController
   end
 
   def redirect_to_documentation_website?
-    return false unless Feature.enabled?(:help_page_documentation_redirect)
     return false unless Gitlab::UrlSanitizer.valid_web?(documentation_url)
 
     true

app/helpers/application_settings_helper.rb

@@ -471,10 +471,6 @@ module ApplicationSettingsHelper
     }
   end
 
-  def show_documentation_base_url_field?
-    Feature.enabled?(:help_page_documentation_redirect)
-  end
-
   def valid_runner_registrars
     Gitlab::CurrentSettings.valid_runner_registrars
   end

app/views/admin/application_settings/_help_page.html.haml

@@ -18,9 +18,8 @@
       = f.text_field :help_page_support_url, class: 'form-control gl-form-input', placeholder: 'https://company.example.com/getting-help', :'aria-describedby' => 'support_help_block'
       %span.form-text.text-muted#support_help_block= _('Alternate support URL for Help page and Help dropdown.')
 
-    - if show_documentation_base_url_field?
     .form-group
-        = f.label :help_page_documentation_base_url, _('Documentation pages URL'), class: 'label-bold'
+      = f.label :help_page_documentation_base_url, _('Documentation pages URL'), class: 'gl-font-weight-bold'
       = f.text_field :help_page_documentation_base_url, class: 'form-control gl-form-input', placeholder: 'https://docs.gitlab.com'
       - docs_link_url = help_page_path('user/admin_area/settings/help_page', anchor: 'destination-requirements')
       - docs_link_start = '<a href="%{url}" target="_blank" rel="noopener noreferrer">'.html_safe % { url: docs_link_url }

config/feature_flags/development/help_page_documentation_redirect.yml

----
-name: help_page_documentation_redirect
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/42702
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/255328
-milestone: '13.5'
-type: development
-group: group::static site editor
-default_enabled: false

doc/user/admin_area/settings/help_page.md

@@ -68,12 +68,9 @@ You can specify a custom URL to which users are directed when they:
 
 ## Redirect `/help` pages
 
-> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/43157) in GitLab 13.5.
-
-FLAG:
-On self-managed GitLab, by default this feature is not available. To make it available, ask an administrator to
-[enable the `:help_page_documentation_redirect` flag](../../../administration/feature_flags.md).
-On GitLab.com, this feature is available but can be configured by GitLab.com administrators only.
+> - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/43157) in GitLab 13.5.
+> - [Feature flag `help_page_documentation_redirect`](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/71737) removed in GitLab 14.4.
+> - [Generally available](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/71737) in GitLab 14.4.
 
 The `/help` URL of a GitLab instance displays a basic version of the documentation sourced from the
 [`doc` directory](https://gitlab.com/gitlab-org/gitlab/-/tree/master/doc) of GitLab. `/help` links

spec/controllers/help_controller_spec.rb

@@ -34,14 +34,6 @@ RSpec.describe HelpController do
         is_expected.to redirect_to("#{documentation_base_url}/ee/#{path}.html")
       end
     end
-
-    context 'when feature flag is disabled' do
-      before do
-        stub_feature_flags(help_page_documentation_redirect: false)
-      end
-
-      it_behaves_like 'documentation pages local render'
-    end
   end
 
   before do

spec/features/admin/admin_settings_spec.rb

@@ -661,8 +661,6 @@ RSpec.describe 'Admin updates settings' do
       end
 
       it 'change Help page' do
-        stub_feature_flags(help_page_documentation_redirect: true)
-
         new_support_url = 'http://example.com/help'
         new_documentation_url = 'https://docs.gitlab.com'
 

spec/helpers/application_settings_helper_spec.rb

@@ -158,26 +158,6 @@ RSpec.describe ApplicationSettingsHelper do
     end
   end
 
-  describe '.show_documentation_base_url_field?' do
-    subject { helper.show_documentation_base_url_field? }
-
-    before do
-      stub_feature_flags(help_page_documentation_redirect: feature_flag)
-    end
-
-    context 'when feature flag is enabled' do
-      let(:feature_flag) { true }
-
-      it { is_expected.to eq(true) }
-    end
-
-    context 'when feature flag is disabled' do
-      let(:feature_flag) { false }
-
-      it { is_expected.to eq(false) }
-    end
-  end
-
   describe '.valid_runner_registrars' do
     subject { helper.valid_runner_registrars }