DOC: lua: Lua configuration documentation

This patch adds the documentation of the Lua configuration directives.
The documentation was read back by Andjelko Iharos.

doc/configuration.txt

@@ -486,6 +486,9 @@ The following keywords are supported in the "global" section :
    - tune.http.cookielen
    - tune.http.maxhdr
    - tune.idletimer
+   - tune.lua.forced-yield
+   - tune.lua.session-timeout
+   - tune.lua.task-timeout
    - tune.maxaccept
    - tune.maxpollevents
    - tune.maxrewrite
@@ -631,6 +634,10 @@ log-tag <string>
   Sometimes it can be useful to differentiate between multiple processes
   running on the same host. See also the per-proxy "log-tag" directive.
 
+lua-load <file>
+  This global directive loads and executes a Lua file. This directive can be
+  used multiple times.
+
 nbproc <number>
   Creates <number> processes when going daemon. This requires the "daemon"
   mode. By default, only one process is created, which is the recommended mode
@@ -983,6 +990,28 @@ tune.idletimer <timeout>
   clicking). There should be not reason for changing this value. Please check
   tune.ssl.maxrecord below.
 
+tune.lua.forced-yield <number>
+  This directive forces the Lua engine to execute a yield each <number> of
+  instructions executed. This permits interruptng a long script and allows the
+  HAProxy scheduler to process other tasks like accepting connections or
+  forwarding traffic. The default value is 10000 instructions. If HAProxy often
+  executes some Lua code but more reactivity is required, this value can be
+  lowered. If the Lua code is quite long and its result is absolutely required
+  to process the data, the <number> can be increased.
+
+tune.lua.session-timeout <timeout>
+  This is the execution timeout for the Lua sessions. This is useful for
+  preventing infinite loops or spending too much time in Lua. This timeout has a
+  priority over other timeouts. For example, if this timeout is set to 4s and
+  you run a 5s sleep, the code will be interrupted with an error after waiting
+  4s.
+
+tune.lua.task-timeout <timeout>
+  Purpose is the same as "tune.lua.session-timeout", but this timeout is
+  dedicated to the tasks. By default, this timeout isn't set because a task may
+  remain alive during of the lifetime of HAProxy. For example, a task used to
+  check servers.
+
 tune.maxaccept <number>
   Sets the maximum number of consecutive connections a process may accept in a
   row before switching to other work. In single process mode, higher numbers
@@ -3109,7 +3138,8 @@ http-request { allow | deny | tarpit | auth [realm <realm>] | redirect <rule> |
               del-acl(<file name>) <key fmt> |
               del-map(<file name>) <key fmt> |
               set-map(<file name>) <key fmt> <value fmt> |
-              { track-sc0 | track-sc1 | track-sc2 } <key> [table <table>]
+              { track-sc0 | track-sc1 | track-sc2 } <key> [table <table>] |
+              lua <function name>
              }
              [ { if | unless } <condition> ]
   Access control for Layer 7 requests
@@ -3356,6 +3386,10 @@ http-request { allow | deny | tarpit | auth [realm <realm>] | redirect <rule> |
       advantage over just checking the keys, because only one table lookup is
       performed for all ACL checks that make use of it.
 
+    - "lua" is used to run a Lua function if the action is executed. The single
+      parameter is the name of the function to run. The prototype of the
+      function is documented in the API documentation.
+
   There is no limit to the number of http-request statements per instance.
 
   It is important to know that http-request rules are processed very early in
@@ -3419,7 +3453,8 @@ http-response { allow | deny | add-header <name> <fmt> | set-nice <nice> |
                 add-acl(<file name>) <key fmt> |
                 del-acl(<file name>) <key fmt> |
                 del-map(<file name>) <key fmt> |
-                set-map(<file name>) <key fmt> <value fmt>
+                set-map(<file name>) <key fmt> <value fmt> |
+                lua <function name>
               }
               [ { if | unless } <condition> ]
   Access control for Layer 7 responses
@@ -3567,6 +3602,10 @@ http-response { allow | deny | add-header <name> <fmt> | set-nice <nice> |
       with large lists! It is the equivalent of the "set map" command from the
       stats socket, but can be triggered by an HTTP response.
 
+    - "lua" is used to run a Lua function if the action is executed. The single
+      parameter is the name of the function to run. The prototype of the
+      function is documented in the API documentation.
+
   There is no limit to the number of http-response statements per instance.
 
   It is important to know that http-response rules are processed very early in
@@ -7797,8 +7836,8 @@ tcp-request content <action> [{if | unless} <condition>]
   Arguments :
     <action>    defines the action to perform if the condition applies. Valid
                 actions include : "accept", "reject", "track-sc0", "track-sc1",
-                "track-sc2" and "capture". See "tcp-request connection" above
+                "track-sc2", "capture" and "lua". See "tcp-request connection"
-                for their signification.
+                above for their signification.
 
     <condition> is a standard layer 4-7 ACL-based condition (see section 7).
 
@@ -7860,6 +7899,11 @@ tcp-request content <action> [{if | unless} <condition>]
   wait until the inspect delay expires when the data to be tracked is not yet
   available.
 
+  The "lua" keyword is followed by a Lua function name. It is used to run a Lua
+  function if the action is executed. The single parameter is the name of the
+  function to run. The prototype of the function is documented in the API
+  documentation.
+
   Example:
         # Accept HTTP requests containing a Host header saying "example.com"
         # and reject everything else.
@@ -7969,7 +8013,7 @@ tcp-response content <action> [{if | unless} <condition>]
                                  no    |    no    |   yes  |   yes
   Arguments :
     <action>    defines the action to perform if the condition applies. Valid
-                actions include : "accept", "close", "reject".
+                actions include : "accept", "close", "reject", "lua".
 
     <condition> is a standard layer 4-7 ACL-based condition (see section 7).
 
@@ -8017,6 +8061,11 @@ tcp-response content <action> [{if | unless} <condition>]
   the best solution involves detecting the HTTP protocol during the inspection
   period.
 
+  The "lua" keyword is followed by a Lua function name. It is used to run a Lua
+  function if the action is executed. The single parameter is the name of the
+  function to run. The prototype of the function is documented in the API
+  documentation.
+
   See section 7 about ACL usage.
 
   See also : "tcp-request content", "tcp-response inspect-delay"