services: nginx: Add lua module.

* gnu/services/web.scm (<nginx-configuration>)
[lua-package-path, lua-package-cpath]: New record types.
* gnu/services/web.scm (default-nginx-config): Use them.
* doc/guix.texi (Web Services): Document this.
* doc/guix-cookbook.texi (System Configuration): Document this.

doc/guix-cookbook.texi

@@ -1353,6 +1353,7 @@ reference.
 * Running Guix on a Linode Server:: Running Guix on a Linode Server
 * Setting up a bind mount:: Setting up a bind mount in the file-systems definition.
 * Getting substitutes from Tor:: Configuring Guix daemon to get substitutes through Tor.
+* Setting up NGINX with Lua:: Configuring NGINX web-server to load Lua modules.
 @end menu
 
 @node Customizing the Kernel
@@ -2114,6 +2115,63 @@ sudo herd set-http-proxy guix-daemon http://localhost:9250
 guix build --substitute-urls=https://bp7o7ckwlewr4slm.onion …
 @end example
 
+@node Setting up NGINX with Lua
+@section Setting up NGINX with Lua
+@cindex nginx, lua, openresty, resty
+
+NGINX could be extended with Lua scripts.
+
+Guix provides NGINX service with ability to load Lua module and specific
+Lua packages, and reply to requests by evaluating Lua scripts.
+
+The following example demonstrates system definition with configuration
+to evaluate @file{index.lua} Lua script on HTTP request to
+@uref{http://localhost/hello} endpoint:
+
+@example
+local shell = require "resty.shell"
+
+local stdin = ""
+local timeout = 1000  -- ms
+local max_size = 4096  -- byte
+
+local ok, stdout, stderr, reason, status =
+   shell.run([[/run/current-system/profile/bin/ls /tmp]], stdin, timeout, max_size)
+
+ngx.say(stdout)
+@end example
+
+@lisp
+(use-modules (gnu))
+(use-service-modules #;… web)
+(use-package-modules #;… lua)
+(operating-system
+  ;; …
+  (services
+   ;; …
+   (service nginx-service-type
+            (nginx-configuration
+             (modules
+              (list
+               (file-append nginx-lua-module "/etc/nginx/modules/ngx_http_lua_module.so")))
+             (lua-package-path (list lua-resty-core
+                                     lua-resty-lrucache
+                                     lua-resty-signal
+                                     lua-tablepool
+                                     lua-resty-shell))
+             (lua-package-cpath (list lua-resty-signal))
+             (server-blocks
+              (list (nginx-server-configuration
+                     (server-name '("localhost"))
+                     (listen '("80"))
+                     (root "/etc")
+                     (locations (list
+                                 (nginx-location-configuration
+                                  (uri "/hello")
+                                  (body (list #~(format #f "content_by_lua_file ~s;"
+                                                        #$(local-file "index.lua"))))))))))))))
+@end lisp
+
 @c *********************************************************************
 @node Advanced package management
 @chapter Advanced package management

doc/guix.texi

@@ -21984,7 +21984,29 @@ names of loadable modules, as in this example:
 (modules
  (list
   (file-append nginx-accept-language-module "\
-/etc/nginx/modules/ngx_http_accept_language_module.so")))
+/etc/nginx/modules/ngx_http_accept_language_module.so")
+  (file-append nginx-lua-module "\
+/etc/nginx/modules/ngx_http_lua_module.so")))
+@end lisp
+
+@item @code{lua-package-path} (default: @code{'()})
+List of nginx lua packages to load.  This should be a list of package
+names of loadable lua modules, as in this example:
+
+@lisp
+(lua-package-path (list lua-resty-core
+                        lua-resty-lrucache
+                        lua-resty-signal
+                        lua-tablepool
+                        lua-resty-shell))
+@end lisp
+
+@item @code{lua-package-cpath} (default: @code{'()})
+List of nginx lua C packages to load.  This should be a list of package
+names of loadable lua C modules, as in this example:
+
+@lisp
+(lua-package-cpath (list lua-resty-signal))
 @end lisp
 
 @item @code{global-directives} (default: @code{'((events . ()))})

gnu/services/web.scm

@@ -13,6 +13,7 @@
 ;;; Copyright © 2020 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2020 Tobias Geerinckx-Rice <me@tobias.gr>
 ;;; Copyright © 2020 Arun Isaac <arunisaac@systemreboot.net>
+;;; Copyright © 2020 Oleg Pykhalov <go.wigust@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -525,6 +526,10 @@ (define-record-type* <nginx-configuration>
   (modules nginx-configuration-modules (default '()))
   (global-directives nginx-configuration-global-directives
                      (default '((events . ()))))
+  (lua-package-path nginx-lua-package-path ;list of <package>
+                    (default #f))
+  (lua-package-cpath nginx-lua-package-cpath ;list of <package>
+                     (default #f))
   (extra-content nginx-configuration-extra-content
                  (default ""))
   (file          nginx-configuration-file         ;#f | string | file-like
@@ -630,6 +635,8 @@ (define (default-nginx-config config)
                  server-names-hash-bucket-max-size
                  modules
                  global-directives
+                 lua-package-path
+                 lua-package-cpath
                  extra-content)
    (apply mixed-text-file "nginx.conf"
           (flatten
@@ -646,11 +653,19 @@ (define (default-nginx-config config)
            "    scgi_temp_path " run-directory "/scgi_temp;\n"
            "    access_log " log-directory "/access.log;\n"
            "    include " nginx "/share/nginx/conf/mime.types;\n"
-           (if server-names-hash-bucket-size
+           (if lua-package-path
-               (string-append
+               #~(format #f "    lua_package_path ~s;~%"
-                "    server_names_hash_bucket_size "
+                         (string-join (map (lambda (path)
-                (number->string server-names-hash-bucket-size)
+                                             (string-append path "/lib/?.lua"))
-                ";\n")
+                                           '#$lua-package-path)
+                                      ";"))
+               "")
+           (if lua-package-cpath
+               #~(format #f "    lua_package_cpath ~s;~%"
+                         (string-join (map (lambda (cpath)
+                                             (string-append cpath "/lib/lua/?.lua"))
+                                           '#$lua-package-cpath)
+                                      ";"))
                "")
            (if server-names-hash-bucket-max-size
                (string-append