Use the current node configuration to populate suggested new URL for Geo node

Users attempting to add a new GeoNode with HTTPS would be suggested
to use an HTTP endpoint, which caused a misconfiguration for one user.

Closes #1416

app/models/geo_node.rb

@@ -5,10 +5,10 @@ class GeoNode < ActiveRecord::Base
   belongs_to :oauth_application, class_name: 'Doorkeeper::Application', dependent: :destroy
   belongs_to :system_hook, dependent: :destroy
 
-  default_values schema: 'http',
+  default_values schema: lambda { Gitlab.config.gitlab.protocol },
                  host: lambda { Gitlab.config.gitlab.host },
-                 port: 80,
-                 relative_url_root: '',
+                 port: lambda { Gitlab.config.gitlab.port },
+                 relative_url_root: lambda { Gitlab.config.gitlab.relative_url_root },
                  primary: false
 
   accepts_nested_attributes_for :geo_node_key, :system_hook

changelogs/unreleased-ee/sh-make-geo-default-schema-match-config.yml

+---
+title: Use the current node configuration to populate suggested new URL for Geo node
+merge_request:
+author:

spec/models/geo_node_spec.rb

@@ -162,6 +162,15 @@ describe GeoNode, type: :model do
       expected_url = 'https://localhost:3000/gitlab'
       expect(new_node.url).to eq(expected_url)
     end
+
+    it 'defaults to existing HTTPS and relative URL if present' do
+      stub_config_setting(port: 443)
+      stub_config_setting(protocol: 'https')
+      stub_config_setting(relative_url_root: '/gitlab')
+      node = GeoNode.new
+
+      expect(node.url).to eq('https://localhost/gitlab')
+    end
   end
 
   describe '#url=' do