FEATURE: add backup directory for mmdb files

This new `DISCOURSE_MAXMIND_BACKUP_PATH` can be used a secondary location
for maxmind db. That way a build machine, for example can cache it on the
host and reuse between builds.

Also per 5bfeef77 added proper error raising for download fails from
dedicated rake task

This also moves "refresh_maxmind_db_during_precompile_days" to a global
setting, it did not make sense in a site setting

lib/tasks/assets.rake

@@ -158,15 +158,75 @@ def concurrent?
   end
 end
 
+def get_mmdb_time(root_path)
+  mmdb_time = nil
+
+  %w{
+    GeoLite2-City
+    GeoLite2-ASN
+  }.map do |name|
+
+    path = File.join(root_path, "#{name}.mmdb")
+
+    if File.exist?(path)
+      mmdb_time = File.mtime(path)
+    else
+      mmdb_time = nil
+      break
+    end
+  end
+
+  mmdb_time
+end
+
+def copy_maxmind(from_path, to_path)
+  puts "Copying MaxMindDB from #{from_path} to #{to_path}"
+
+  %w{
+    GeoLite2-City
+    GeoLite2-ASN
+  }.each do |name|
+    from = File.join(from_path, "#{name}.mmdb")
+    to = File.join(to_path, "#{name}.mmdb")
+    FileUtils.cp(from, to, preserve: true)
+  end
+end
+
 task 'assets:precompile' => 'assets:precompile:before' do
-  if refresh_days = SiteSetting.refresh_maxmind_db_during_precompile_days
-    mmdb_path = DiscourseIpInfo.mmdb_path('GeoLite2-City')
-    mmdb_time = File.exist?(mmdb_path) && File.mtime(mmdb_path)
+
+  refresh_days = GlobalSetting.refresh_maxmind_db_during_precompile_days
+
+  if refresh_days.to_i > 0
+
+    mmdb_time = get_mmdb_time(DiscourseIpInfo.path)
+
+    backup_mmdb_time =
+      if GlobalSetting.maxmind_backup_path.present?
+        get_mmdb_time(GlobalSetting.maxmind_backup_path)
+      end
+
+    mmdb_time ||= backup_mmdb_time
+    if backup_mmdb_time && backup_mmdb_time >= mmdb_time
+      copy_maxmind(GlobalSetting.maxmind_backup_path, DiscourseIpInfo.path)
+    end
+
     if !mmdb_time || mmdb_time < refresh_days.days.ago
       puts "Downloading MaxMindDB..."
       mmdb_thread = Thread.new do
-        DiscourseIpInfo.mmdb_download('GeoLite2-City')
-        DiscourseIpInfo.mmdb_download('GeoLite2-ASN')
+        begin
+          DiscourseIpInfo.mmdb_download('GeoLite2-City')
+          DiscourseIpInfo.mmdb_download('GeoLite2-ASN')
+
+          if GlobalSetting.maxmind_backup_path.present?
+            copy_maxmind(DiscourseIpInfo.path, GlobalSetting.maxmind_backup_path)
+          end
+
+        rescue OpenURI::HTTPError => e
+          STDERR.puts("*" * 100)
+          STDERR.puts("MaxMindDB (#{name}) could not be downloaded: #{e}")
+          STDERR.puts("*" * 100)
+          Rails.logger.warn("MaxMindDB (#{name}) could not be downloaded: #{e}")
+        end
       end
     end
   end