Fixes #2628: KB link to public interface loses HTTP type.

app/assets/javascripts/app/views/knowledge_base/base_form.coffee

@@ -116,9 +116,8 @@ class App.KnowledgeBaseCustomAddressForm extends App.KnowledgeBaseForm
   openSnippetsModal: (e) ->
     @preventDefaultAndStopPropagation(e)
 
-    loader = new App.ControllerModalLoading(
+    button = e.currentTarget
-      container: @el.closest('.main')
+    button.disabled = true
-    )
 
     @ajax(
       id:          'knowledge_bases_init_admin'
@@ -126,7 +125,7 @@ class App.KnowledgeBaseCustomAddressForm extends App.KnowledgeBaseForm
       url:         @object().manageUrl('server_snippets')
       processData: true
       success:     (data, status, xhr) =>
-        loader.hide()
+        button.disabled = false
 
         new App.KnowledgeBaseServerSnippet(
           container:    @el.closest('.main')
@@ -135,7 +134,7 @@ class App.KnowledgeBaseCustomAddressForm extends App.KnowledgeBaseForm
           address_type: data.address_type
         )
       error:       (xhr) =>
-        loader.hide()
+        button.disabled = false
 
         if xhr.status != 422
           return

app/controllers/knowledge_base/public/categories_controller.rb

@@ -39,7 +39,7 @@ class KnowledgeBase::Public::CategoriesController < KnowledgeBase::Public::BaseC
 
     path = help_root_path(locale: primary_locale.locale)
 
-    redirect_to custom_path_if_needed(path, knowledge_base)
+    redirect_to custom_path_if_needed(path, knowledge_base, full: true)
   end
 
   private

app/helpers/knowledge_base_helper.rb

@@ -5,13 +5,20 @@ module KnowledgeBaseHelper
     knowledge_base.send("#{layout_prefix}_layout")
   end
 
-  def custom_path_if_needed(path, knowledge_base)
+  def custom_path_if_needed(path, knowledge_base, full: false)
-    return path if knowledge_base.custom_address_matches? request
+    return path unless knowledge_base.custom_address_matches? request
 
-    prefix = knowledge_base.custom_address_uri&.path
+    custom_address = knowledge_base.custom_address_uri
-    return path if prefix.nil?
+    return path unless custom_address
 
-    path.gsub(%r{^\/help}, prefix).presence || '/'
+    output = path.gsub(%r{^\/help}, custom_address.path || '').presence || '/'
+
+    if full
+      fqdn = request.headers.env['SERVER_NAME']
+      output = "#{custom_address.scheme}://#{custom_address.host || fqdn}#{output}"
+    end
+
+    output
   end
 
   def translation_locale_code(translation)

app/models/knowledge_base.rb

@@ -63,7 +63,9 @@ class KnowledgeBase < ApplicationModel
   def custom_address_uri
     return nil if custom_address.blank?
 
-    URI("protocol://#{custom_address}")
+    scheme = Setting.get('http_type') || 'http'
+
+    URI("#{scheme}://#{custom_address}")
   rescue URI::InvalidURIError
     nil
   end