require 'rack/file' module Rack # = Sendfile # # The Sendfile middleware intercepts responses whose body is being # served from a file and replaces it with a server specific X-Sendfile # header. The web server is then responsible for writing the file contents # to the client. This can dramatically reduce the amount of work required # by the Ruby backend and takes advantage of the web server's optimized file # delivery code. # # In order to take advantage of this middleware, the response body must # respond to +to_path+ and the request must include an X-Sendfile-Type # header. Rack::File and other components implement +to_path+ so there's # rarely anything you need to do in your application. The X-Sendfile-Type # header is typically set in your web servers configuration. The following # sections attempt to document # # === Nginx # # Nginx supports the X-Accel-Redirect header. This is similar to X-Sendfile # but requires parts of the filesystem to be mapped into a private URL # hierarachy. # # The following example shows the Nginx configuration required to create # a private "/files/" area, enable X-Accel-Redirect, and pass the special # X-Sendfile-Type and X-Accel-Mapping headers to the backend: # # location ~ /files/(.*) { # internal; # alias /var/www/$1; # } # # location / { # proxy_redirect off; # # proxy_set_header Host $host; # proxy_set_header X-Real-IP $remote_addr; # proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; # # proxy_set_header X-Sendfile-Type X-Accel-Redirect; # proxy_set_header X-Accel-Mapping /var/www/=/files/; # # proxy_pass http://127.0.0.1:8080/; # } # # Note that the X-Sendfile-Type header must be set exactly as shown above. # The X-Accel-Mapping header should specify the location on the file system, # followed by an equals sign (=), followed name of the private URL pattern # that it maps to. The middleware performs a simple substitution on the # resulting path. # # See Also: http://wiki.codemongers.com/NginxXSendfile # # === lighttpd # # Lighttpd has supported some variation of the X-Sendfile header for some # time, although only recent version support X-Sendfile in a reverse proxy # configuration. # # $HTTP["host"] == "example.com" { # proxy-core.protocol = "http" # proxy-core.balancer = "round-robin" # proxy-core.backends = ( # "127.0.0.1:8000", # "127.0.0.1:8001", # ... # ) # # proxy-core.allow-x-sendfile = "enable" # proxy-core.rewrite-request = ( # "X-Sendfile-Type" => (".*" => "X-Sendfile") # ) # } # # See Also: http://redmine.lighttpd.net/wiki/lighttpd/Docs:ModProxyCore # # === Apache # # X-Sendfile is supported under Apache 2.x using a separate module: # # https://tn123.org/mod_xsendfile/ # # Once the module is compiled and installed, you can enable it using # XSendFile config directive: # # RequestHeader Set X-Sendfile-Type X-Sendfile # ProxyPassReverse / http://localhost:8001/ # XSendFile on class Sendfile F = ::File def initialize(app, variation=nil) @app = app @variation = variation end def call(env) status, headers, body = @app.call(env) if body.respond_to?(:to_path) case type = variation(env) when 'X-Accel-Redirect' path = F.expand_path(body.to_path) if url = map_accel_path(env, path) headers['Content-Length'] = '0' headers[type] = url body = [] else env['rack.errors'].puts "X-Accel-Mapping header missing" end when 'X-Sendfile', 'X-Lighttpd-Send-File' path = F.expand_path(body.to_path) headers['Content-Length'] = '0' headers[type] = path body = [] when '', nil else env['rack.errors'].puts "Unknown x-sendfile variation: '#{variation}'.\n" end end [status, headers, body] end private def variation(env) @variation || env['sendfile.type'] || env['HTTP_X_SENDFILE_TYPE'] end def map_accel_path(env, file) if mapping = env['HTTP_X_ACCEL_MAPPING'] internal, external = mapping.split('=', 2).map{ |p| p.strip } file.sub(/^#{internal}/i, external) end end end end