Redmine

Despite uncommenting X-Sendfile option in config/additional_environment.rb, X-Sendfile header is not added into the response. Therefore the download is not handed over to the webserver and it is processed by the application. It prevents from downloading of large files.

config/additional_environment.rb

# Specifies the header that your server uses for sending files
config.action_dispatch.x_sendfile_header = "X-Sendfile" 

Response header when downloading a file from the Files module:

Cache-Control private
Connection Keep-Alive
Content-Disposition attachment; filename="file.zip"
Content-Length 25362
Content-Type application/x-zip-compressed
Date Mon, 19 Dec 2016 08:33:42 GMT
Etag "c4c34e17fd91b5e7f97ea03a1e4366f6"
Server WEBrick/1.3.1 (Ruby/2.3.1/2016-04-26)
Set-Cookie _redmine_session=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--150df285ffe701a4ef1e1bad01398101dcb4989c; path=/; HttpOnly
X-Content-Type-Options nosniff
X-Frame-Options SAMEORIGIN
X-Request-Id 8743fb81-42d3-4924-b93f-199b95e68ed1
X-Runtime 0.030291
X-XSS-Protection 1; mode=block
content-transfer-encoding binary

My environment:

Environment:
  Redmine version                3.3.1.stable
  Ruby version                   2.3.1-p112 (2016-04-26) [x86_64-linux-gnu]
  Rails version                  4.2.7.1
  Environment                    production
  Database adapter               Mysql2