Lua Web Server API


WSAPI is an API that abstracts the web server from Lua web applications. By coding against WSAPI your application can run on any of the supported servers and interfaces (currently CGI, FastCGI and Xavante, on Windows and UNIX-based systems).

WSAPI provides a set of helper libraries that help with request processing and output buffering. You can also write applications that act as filters that provide some kind of service to other applications, such as authentication, file uploads, request isolation, or multiplexing.

WSAPI's main influence is Ruby's Rack framework, but it was also influenced by Python's WSGI (PEP 333). It's not a direct clone of either of them, though, and tries to follow standard Lua idioms.

WSAPI is free software and uses the same license as Lua 5.1.


Current version is 1.6.1. It supports both Lua 5.1 and Lua 5.2.


You can get WSAPI using LuaRocks:

luarocks install wsapi-xavante

Unix Installer Script

You can also get an installer script that installs Lua+LuaRocks+WSAPI here. See the manual for installation instructions.

Customizing the installer

There is a section of wsapi-install-1.6 with the parameters that control the installer:

# Installer parameters


To install something else change PACKAGE to the full name of the package, PACKAGE_OPT to the name of the --with-foo option that lets the user override the version (or skip installation of the package), PACKAGE_ROCK to the name of the rock, and PACKAGE_VERSION to the version. Also change LUAROCKS_REPO if you want to use another repository (the installer uses --from, so will pull packages from other repositories if the one you specified does not have them).

If there is a LuaRocks update then change LUAROCKS_URL and LUAROCKS_VERSION. Changing Lua version is much more involved, so I won't go into that.

Now to make the tarball, put the installer script in an empty folder and run:

bash ./your-install-script --prefix=/tmp/anything --bootstrap

After it finishes you will have lua-5.2.1.tar.gz, luarocks-2.0.12.tar.gz, and a rocks folder with for all the rocks that the installer installs.

Latest Sources and Bug Tracker

WSAPI sources and bug tracker are available at its Github page.


WSAPI 1.6.1 [21/Mar/2014]

  • Restores Lua 5.1 compatibility (incorrect usage of coxpcall)
  • Improvements to wsapi.mock
  • wsapi.request.qs_encode produces proper querystrings
  • FastCGI fixes
  • Additional options for cookies such as httponly and max age.

WSAPI 1.6 [30/Jan/2013]

  • Lua 5.2 compatibility

WSAPI 1.5 [21/Apr/2011]

  • Add lfcgi.finish() to lfcgi, to close the current FastCGI request in case the application does not want to call lfcgi.accept() right away
  • Fix response headers in sapi.lua
  • Fix reloading in non-isolated launchers
  • Errors in mock handler now go in response.wsapi_errors

WSAPI 1.4 [19/Nov/2010]

  • Remove unecessary !# from sapi.lua
  • Added mock WSAPI handler (by Norman Clarke)
  • Flush output pipe after writing content
  • Respect rules specified in config file for wsapi launcher
  • Fix bug where common.load_wsapi would not return the module if it was already require'd
  • Fix bug where wsapi.ringer would try to close an already closed state
  • Refactoring of request, response, and util modules, to work with mk
  • New methods for wsapi.request: qs_encode (encodes a table as a query string), route_link (makes a link to a mk route, link (makes an internal app link), absolute_link (makes an absolute link), static_link (makes an external link), empty (checks if a string is just blanks or nil), empty_param (checks if a request param is empty), and renamed parse_post_data method to parse_post
  • New methods for wsapi.response: forward (sets path_info and returns an mk "keep parsing" code), content_type (sets Content-Type header), redirect (sets Location header and returns redirect WSAPI response), changed write to take multiple parameters and flatten nested tables
  • New functions in wsapi.util: make_env_get (makes a mock WSAPI environment for a GET request from a query string), make_env_post (makes a mock WSAPI environment for a POST request from a postdata string, a postdata type, default x-www-form-urlencoded, and a query string)

WSAPI 1.3.4 [23/Mar/2010]

  • Bugfix release, fix bug introduced by previous fix :-)

WSAPI 1.3.3 [22/Mar/2010]

  • Bugfix release, fix memory leak with reload option for persistent loaders

WSAPI 1.3.2 [19/Mar/2010]

  • Bugfix release, do not send Transfer-Encoding header unless it is raw HTTP response

WSAPI 1.3.1 [19/Mar/2010]

  • Bugfix release, fix the unknown symbol in lfcgi.getenv()

WSAPI 1.3 [18/Mar/2010]

  • Fixed segmentation fault when non-string is provided to lfcgi.getenv() (thanks to mkottman@github)
  • Added CGILua bootstrap to wsapi.sapi, so CGILua can run without a kepler_init module present
  • Added an extra_vars paremeter to wsapi.xavante.makeHandler and wsapi.xavante.makeGenericHandler, to let you pass extra variables in the WSAPI environment
  • Added overwrite option to wsapi.request that tells the parameter parser to overwrite repeated parameters instead of collecting them in a list
  • Added a parameter isolated to the persistent generic loaders that controls whether you isolate each script in a Lua state or not
  • Added parameters to the persistent generic loaders that let the user control the life cycle of Lua states: period sets how long WSAPI should wait between collecting stale states, and ttl sets the period after which a state becomes stale
  • Fixed bug in wsapi.ringer that didn't let you use wsapi.input:read inside the response iterator
  • Parameter vars for the WSAPI generic loaders that which variables WSAPI should check to get the physical path of the script, and in which order. Defaults tro trying SCRIPT_FILENAME first and PATH_TRANSLATED second

WSAPI 1.2 [27/Oct/2009]

  • Adds time-based collection of Lua states to FCGI and Xavante launchers
  • Adds "wsapi" laucher script, to start a Xavante WSAPI server
  • Fixed "undefined media type" error
  • Added is_empty utility function to check if a string is nil or ''
  • Fixed bug with empty bodies in wsapi.xavante, and added full http status codes to responses
  • Changing order of evaluating PATH_TRANSLATED and SCRIPT_FILENAME, to make non-wrapped launchers work in OSX Apache
  • Reload support for load_isolated_launcher

WSAPI 1.1 [04/Feb/2009]

  • Adds options table to, *delay_post* option delays POST processing until req:parsepostdata() is called
  • Moves call to lfs.setmode from wsapi.common to wsapi.cgi
  • Adds wsapi.util.make_rewindable(wsapi_env) method - wraps wsapi_env in a new environment that lets you process the POST data more than once.
  • Correctly handles PATH_TRANSLATED and SCRIPT_FILENAME in case the web server gets creative
  • Statically links the FastCGI version on Windows

WSAPI 1.0 [18/May/2008]

  • First public version.
  • Includes CGI, FastCGI and Xavante WSAPI connectors.


WSAPI was designed and developed by Fabio Mascarenhas and André Carregal, and is maintained by Fabio Mascarenhas.

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