Apache Module mod_lua

apache2.conf LuaHookTranslateName /scripts/conf/hooks.lua silly_mapper

This module allows the server to be extended with scripts written in the Lua programming language. The extension points (hooks) available with

include many of the hooks available to natively compiled Apache HTTP Server modules, such as mapping requests to files, generating dynamic responses, access control, authentication, and authorizationmod_lua

More information on the Lua programming language can be found at the the Lua website.

is still in experimental state. Until it is declared stable, usage and behavior may change at any time, even between stable releases of the 2.4.x series. Be sure to check the CHANGES file before upgrading.This module holds a great deal of power over httpd, which is both a strength and a potential security risk. It is not recommended that you use this module on a server that is shared with users you do not trust, as it can be abused to change the internal workings of httpd.

LoadModule luamodule modules/modlua.so

to handle requests for files ending in .lua

For more flexibility, see LuaMapHandler

always looks to invoke a Lua function for the handler, rather than just evaluating a script body CGI style. A handler function looks something like this:

-- example handler require "string" --[[ This is the default method name for Lua handlers, see the optional function-name in the LuaMapHandler directive to choose a different entry point. --]] function handle(r) r.content_type = "text/plain" if r.method == 'GET' then r:puts("Hello Lua World!\n") for k, v in pairs( r:parseargs() ) do r:puts( string.format("%s: %s\n", k, v) ) end elseif r.method == 'POST' then r:puts("Hello Lua World!\n") for k, v in pairs( r:parsebody() ) do r:puts( string.format("%s: %s\n", k, v) ) end elseif r.method == 'PUT' then -- use our own Error contents r:puts("Unsupported HTTP method " .. r.method) r.status = 405 return apache2.ok else -- use the ErrorDocument return 501 end return apache2.OK end

This handler function just prints out the uri or form encoded arguments to a plaintext page.

This means (and in fact encourages) that you can have multiple handlers (or hooks, or filters) in the same script.

will call the authorization provider of the given name, passing the rest of the line as parameters. The provider will then check authorization and pass the result as return value.modauthzcore

The authz provider is normally called before authentication. If it needs to know the authenticated user name (or if the user will be authenticated at all), the provider must return apache2.AUTHZDENIEDNO_USER

. This will cause authentication to proceed and the authz provider to be called a second time.

The following authz provider function takes two arguments, one ip address and one user name. It will allow access from the given ip address without authentication, or if the authenticated user matches the second argument:

require 'apache2' function authzcheckfoo(r, ip, user) if r.useragentip == ip then return apache2.AUTHZGRANTED elseif r.user == nil then return apache2.AUTHZDENIEDNOUSER elseif r.user == user then return apache2.AUTHZGRANTED else return apache2.AUTHZ_DENIED end end

and configures it for URL /

LuaAuthzProvider foo authzprovider.lua authzcheckfoo Require foo 10.1.2.3 johndoe

| Hook phase | modlua directive | Description | |---|---|---| | Quick handler | | This is the first hook that will be called after a request has been mapped to a host or virtual host | | Translate name | | This phase translates the requested URI into a filename on the system. Modules such as and operate in this phase. | | Map to storage | | This phase maps files to their physical, cached or external/proxied storage. It can be used by proxy or caching modules | | Check Access | | This phase checks whether a client has access to a resource. This phase is run before the user is authenticated, so beware. | | Check User ID | | This phase it used to check the negotiated user ID | | Check Authorization | or | This phase authorizes a user based on the negotiated credentials, such as user ID, client certificate etc. | | Check Type | | This phase checks the requested file and assigns a content type and a handler to it | | Fixups | | This is the final "fix anything" phase before the content handlers are run. Any last-minute changes to the request should be made here. | | Content handler | fx. .lua files or through | This is where the content is handled. Files are read, parsed, some are run, and the result is sent to the client | | Logging | | Once a request has been handled, it enters several logging phases, which logs the request in either the error or access log. Modlua is able to hook into the start of this and control logging output. |

Hook functions are passed the request object as their only argument (except for LuaAuthzProvider, which also gets passed the arguments from the Require directive). They can return any value, depending on the hook, but most commonly they'll return OK, DONE, or DECLINED, which you can write in Lua as apache2.OK

-- example hook that rewrites the URI to a filesystem path. require 'apache2' function translatename(r) if r.uri == "/translate-name" then r.filename = r.documentroot .. "/find_me.txt" return apache2.OK end -- we don't care about this URL, give another module a chance return apache2.DECLINED end

--[[ example hook that rewrites one URI to another URI. It returns a apache2.DECLINED to give other URL mappers a chance to work on the substitution, including the core translatename hook which maps based on the DocumentRoot. Note: Use the early/late flags in the directive to make it run before or after modalias. --]] require 'apache2' function translatename(r) if r.uri == "/translate-name" then r.uri = "/findme.txt" return apache2.DECLINED end return apache2.DECLINED end

The requestrec is mapped in as a userdata. It has a metatable which lets you do useful things with it. For the most part it has the same fields as the requestrec struct, many of which are writable as well as readable. (The table fields' content can be changed, but the fields themselves cannot be set to different tables.)

Name | Lua type | Writable | Description | |---|---|---|---| allowoverrides | string | no | The AllowOverride options applied to the current request. | apauthtype | string | no | If an authentication check was made, this is set to the type of authentication (f.x. basic ) | args | string | yes | The query string arguments extracted from the request (f.x. foo=bar&name=johnsmith ) | assbackwards | boolean | no | Set to true if this is an HTTP/0.9 style request (e.g. GET /foo (with no headers) ) | authname | string | no | The realm name used for authorization (if applicable). | banner | string | no | The server banner, f.x. Apache HTTP Server/2.4.3 openssl/0.9.8c | basicauthpw | string | no | The basic auth password sent with this request, if any | canonicalfilename | string | no | The canonical filename of the request | contentencoding | string | no | The content encoding of the current request | contenttype | string | yes | The content type of the current request, as determined in the typecheck phase (f.x. image/gif or text/html ) | contextprefix | string | no | | contextdocumentroot | string | no | | documentroot | string | no | The document root of the host | errheadersout | table | no | MIME header environment for the response, printed even on errors and persist across internal redirects | filename | string | yes | The file name that the request maps to, f.x. /www/example.com/foo.txt. This can be changed in the translate-name or map-to-storage phases of a request to allow the default handler (or script handlers) to serve a different file than what was requested. | handler | string | yes | The name of the lua-script if it is to be served by modlua. This is typically set by the or directives, but could also be set via mod_lua to allow another handler to serve up a specific request that would otherwise not be served by it. |

Host, User-Agent, Referer

header or by a full URI.is_https

r:flush() -- flushes the output buffer. -- Returns true if the flush was successful, false otherwise. while wehavestufftosend do r:puts("Bla bla bla\n") -- print something to client r:flush() -- flush the buffer (send to client) r.usleep(500000) -- fake processing time for 0.5 sec. and repeat end

r:addoutputfilter(name|function) -- add an output filter: r:addoutputfilter("fooFilter") -- add the fooFilter to the output stream

r:sendfile(filename) -- sends an entire file to the client, using sendfile if supported by the current platform: if usesendfilething then r:sendfile("/var/www/large_file.img") end

r:parseargs() -- returns two tables; one standard key/value table for regular GET data, -- and one for multi-value data (fx. foo=1&foo=2&foo=3): local GET, GETMULTI = r:parseargs() r:puts("Your name is: " .. GET['name'] or "Unknown")

r:parsebody([sizeLimit]) -- parse the request body as a POST and return two lua tables, -- just like r:parseargs(). -- An optional number may be passed to specify the maximum number -- of bytes to parse. Default is 8192 bytes: local POST, POSTMULTI = r:parsebody(1024*1024) r:puts("Your name is: " .. POST['name'] or "Unknown")

r:puts("hello", " world", "!") -- print to response body, self explanatory

r:escape_html("test") -- Escapes HTML code and returns the escaped result

r:base64encode(string) -- Encodes a string using the Base64 encoding standard: local encoded = r:base64encode("This is a test") -- returns VGhpcyBpcyBhIHRlc3Q=

r:base64decode(string) -- Decodes a Base64-encoded string: local decoded = r:base64decode("VGhpcyBpcyBhIHRlc3Q=") -- returns 'This is a test'

r:md5(string) -- Calculates and returns the MD5 digest of a string (binary safe): local hash = r:md5("This is a test") -- returns ce114e4501d2f4e2dcea3e17b546f339

r:sha1(string) -- Calculates and returns the SHA1 digest of a string (binary safe): local hash = r:sha1("This is a test") -- returns a54d88e06612d820bc3be72877c74f257b561b19

r:escape(string) -- URL-Escapes a string: local url = "http://foo.bar/1 2 3 & 4 + 5" local escaped = r:escape(url) -- returns 'http%3a%2f%2ffoo.bar%2f1+2+3+%26+4+%2b+5'

r:unescape(string) -- Unescapes an URL-escaped string: local url = "http%3a%2f%2ffoo.bar%2f1+2+3+%26+4+%2b+5" local unescaped = r:unescape(url) -- returns 'http://foo.bar/1 2 3 & 4 + 5'

r:constructurl(string) -- Constructs an URL from an URI local url = r:constructurl(r.uri)

r.mpmquery(number) -- Queries the server for MPM information using apmpmquery: local mpm = r.mpmquery(14) if mpm == 1 then r:puts("This server uses the Event MPM") end

r:expr(string) -- Evaluates an[expr]string. if r:expr("%{HTTP_HOST} =~ /^www/") then r:puts("This host name starts with www") end

r:scoreboard_process(a) -- Queries the server for information about the process at position a

r:scoreboard_worker(a, b) -- Queries for information about the worker thread,b

r:clock() -- Returns the current time with microsecond precision

r:requestbody(filename) -- Reads and returns the request body of a request. -- If 'filename' is specified, it instead saves the -- contents to that file: local input = r:requestbody() r:puts("You sent the following request body to me:\n") r:puts(input)

r:addinputfilter(filtername) -- Adds 'filtername' as an input filter

r.moduleinfo(modulename) -- Queries the server for information about a module local mod = r.moduleinfo("modlua.c") if mod then for k, v in pairs(mod.commands) do r:puts( ("%s: %s\n"):format(k,v)) -- print out all directives accepted by this module end end

r:loadedmodules() -- Returns a list of modules loaded by httpd: for k, module in pairs(r:loadedmodules()) do r:puts("I have loaded module " .. module .. "\n") end

r:runtimedirrelative(filename) -- Compute the name of a run-time file (e.g., shared memory "file") -- relative to the appropriate run-time directory.

r:server_info() -- Returns a table containing server information, such as -- the name of the httpd executable file, mpm used etc.

r:setdocumentroot(filepath) -- Sets the document root for the request to filepath

r:setcontextinfo(prefix, docroot) -- Sets the context prefix and context document root for a request

r:osescapepath(file_path) -- Converts an OS path to a URL in an OS dependent way

r.strcmpmatch(string, pattern) -- Checks if 'string' matches 'pattern' using strcmpmatch (globs). -- fx. whether 'www.example.com' matches '.example.com': local match = r.strcmp_match("foobar.com", "foo.com") if match then r:puts("foobar.com matches foo*.com") end

r:set_keepalive() -- Sets the keepalive status for a request. Returns true if possible, false otherwise.

r:make_etag() -- Constructs and returns the etag for the current request.

r:sendinterimresponse(clear) -- Sends an interim (1xx) response to the client. -- if 'clear' is true, available headers will be sent and cleared.

r:customresponse(statuscode, string) -- Construct and set a custom response for a given status code. -- This works much like the ErrorDocument directive: r:custom_response(404, "Baleted!")

r.existsconfigdefine(string) -- Checks whether a configuration definition exists or not: if r.existsconfigdefine("FOO") then r:puts("httpd was probably run with -DFOO, or it was defined in the configuration") end

r:stat(filename [,wanted]) -- Runs stat() on a file, and returns a table with file information: local info = r:stat("/var/www/foo.txt") if info then r:puts("This file exists and was last modified at: " .. info.modified) end

r:regex(string, pattern [,flags]) -- Runs a regular expression match on a string, returning captures if matched: local matches = r:regex("foo bar baz", [[foo (\w+) (\S*)]]) if matches then r:puts("The regex matched, and the last word captured ($2) was: " .. matches[2]) end -- Example ignoring case sensitivity: local matches = r:regex("FOO bar BAz", [[(foo) bar]], 1) -- Flags can be a bitwise combination of: -- 0x01: Ignore case -- 0x02: Multiline search

r.usleep(numberofmicroseconds) -- Puts the script to sleep for a given number of microseconds.

r:dbacquire(dbType[, dbParams]) -- Acquires a connection to a database and returns a database class. -- See '[Database connectivity]' for details.

r:ivmset("key", value) -- Set an Inter-VM variable to hold a specific value. -- These values persist even though the VM is gone or not being used, -- and so should only be used if MaxConnectionsPerChild is > 0 -- Values can be numbers, strings and booleans, and are stored on a -- per process basis (so they won't do much good with a prefork mpm) r:ivmget("key") -- Fetches a variable set by ivmset. Returns the contents of the variable -- if it exists or nil if no such variable exists. -- An example getter/setter that saves a global variable outside the VM: function handle(r) -- First VM to call this will get no value, and will have to create it local foo = r:ivmget("cacheddata") if not foo then foo = dosomecalcs() -- fake some return value r:ivmset("cached_data", foo) -- set it globally end r:puts("Cached data is: ", foo) end

r:htpassword(string [,algorithm [,cost]]) -- Creates a password hash from a string. -- algorithm: 0 = APMD5 (default), 1 = SHA, 2 = BCRYPT, 3 = CRYPT. -- cost: only valid with BCRYPT algorithm (default = 5).

r:mkdir(dir [,mode]) -- Creates a directory and sets mode to optional mode paramter.

r:mkrdir(dir [,mode]) -- Creates directories recursive and sets mode to optional mode paramter.

r:rmdir(dir) -- Removes a directory.

r:touch(file [,mtime]) -- Sets the file modification time to current time or to optional mtime msec value.

r:getdirentries(dir) -- Returns a table with all directory entries. function handle(r) local dir = r.contextdocumentroot for , f in ipairs(r:get_direntries(dir)) do local info = r:stat(dir .. "/" .. f) if info then local mtime = os.date(fmt, info.mtime / 1000000) local ftype = (info.filetype == 2) and "[dir] " or "[file]" r:puts( ("%s %s %10i %s\n"):format(ftype, mtime, info.size, f) ) end end end

r.dateparserfc(string) -- Parses a date/time string and returns seconds since epoche.

r:getcookie(key) -- Gets a HTTP cookie

r:setcookie{ key = [key], value = [value], expires = [expiry], secure = [boolean], httponly = [boolean], path = [path], domain = [domain] } -- Sets a HTTP cookie, for instance: r:setcookie{ key = "cookie1", value = "HDHfa9eyffh396rt", expires = os.time() + 86400, secure = true }

r:wsupgrade() -- Upgrades a connection to WebSockets if possible (and requested): if r:wsupgrade() then -- if we can upgrade: r:wswrite("Welcome to websockets!") -- write something to the client r:wsclose() -- goodbye! end

r:wsread() -- Reads a WebSocket frame from a WebSocket upgraded connection (see above): local line, isFinal = r:wsread() -- isFinal denotes whether this is the final frame. -- If it isn't, then more frames can be read r:wswrite("You wrote: " .. line)

r:wsclose() -- Closes a WebSocket request and terminates it for httpd: if r:wsupgrade() then r:wswrite("Write something: ") local line = r:wsread() or "nothing" r:wswrite("You wrote: " .. line); r:wswrite("Goodbye!") r:wsclose() end

r:trace1("This is a trace log message") -- trace1 through trace8 can be used

r:debug("This is a debug log message")

r:notice("This is a notice log message")

r:warn("This is a warn log message")

r:alert("This is an alert log message")

r:crit("This is a crit log message")

r:emerg("This is an emerg log message")

function filter(r) -- Our first yield is to signal that we are ready to receive buckets. -- Before this yield, we can set up our environment, check for conditions, -- and, if we deem it necessary, decline filtering a request alltogether: if something_bad then return -- This would skip this filter. end -- Regardless of whether we have data to prepend, a yield MUST be called here. -- Note that only output filters can prepend data. Input filters must use the -- final stage to append data to the content. coroutine.yield([optional header to be prepended to the content]) -- After we have yielded, buckets will be sent to us, one by one, and we can -- do whatever we want with them and then pass on the result. -- Buckets are stored in the global variable 'bucket', so we create a loop -- that checks if 'bucket' is not nil: while bucket ~= nil do local output = mangle(bucket) -- Do some stuff to the content coroutine.yield(output) -- Return our new content to the filter chain end -- Once the buckets are gone, 'bucket' is set to nil, which will exit the -- loop and land us here. Anything extra we want to append to the content -- can be done by doing a final yield here. Both input and output filters -- can append data to the content in this phase. coroutine.yield([optional footer to be appended to the content]) end

The example below shows how to acquire a database handle and return information from a table:

function handle(r) -- Acquire a database handle local database, err = r:dbacquire("mysql", "server=localhost,user=someuser,pass=somepass,dbname=mydb") if not err then -- Select some information from it local results, err = database:select(r, "SELECT name, age FROM people WHERE 1") if not err then local rows = results(0) -- fetch all rows synchronously for k, row in pairs(rows) do r:puts( string.format("Name: %s, Age: %s
", row[1], row[2]) ) end else r:puts("Database query error: " .. err) end database:close() else r:puts("Could not connect to the database: " .. err) end end

as the database type, or leave the field blank:

-- Run a statement and return the number of rows affected: local affected, errmsg = database:query(r, "DELETE FROM tbl WHERE 1") -- Run a statement and return a result set that can be used synchronously or async: local result, errmsg = database:select(r, "SELECT * FROM people WHERE 1")

Using prepared statements (recommended):

-- Create and run a prepared statement: local statement, errmsg = database:prepare(r, "DELETE FROM tbl WHERE age > %u") if not errmsg then local result, errmsg = statement:query(20) -- run the statement with age > 20 end -- Fetch a prepared statement from a DBDPrepareSQL directive: local statement, errmsg = database:prepared(r, "someTag") if not errmsg then local result, errmsg = statement:select("John Doe", 123) -- inject the values "John Doe" and 123 into the statement end

Escaping values, closing databases etc:

-- Escape a value for use in a statement: local escaped = database:escape(r, [["'|blabla]]) -- Close a database connection and free up handles: database:close() -- Check whether a database connection is up and running: local connected = database:active()

fetches all rows in a synchronous manner, returning a table of rows.

fetches the next available row in the set, asynchronously.

-- fetch a result set using a regular query: local result, err = db:select(r, "SELECT * FROM tbl WHERE 1") local rows = result(0) -- Fetch ALL rows synchronously local row = result(-1) -- Fetch the next available row, asynchronously local row = result(1234) -- Fetch row number 1234, asynchronously local row = result(-1, true) -- Fetch the next available row, using row names as key indexes.

One can construct a function that returns an iterative function to iterate over all rows in a synchronous or asynchronous way, depending on the async argument:

function rows(resultset, async) local a = 0 local function getnext() a = a + 1 local row = resultset(-1) return row and a or nil, row end if not async then return pairs(resultset(0)) else return getnext, self end end local statement, err = db:prepare(r, "SELECT * FROM tbl WHERE age > %u") if not err then -- fetch rows asynchronously: local result, err = statement:select(20) if not err then for index, row in rows(result, true) do .... end end -- fetch rows synchronously: local result, err = statement:select(20) if not err then for index, row in rows(result, false) do .... end end end

when they are no longer needed. If you do not close them manually, they will eventually be garbage collected and closed by modlua, but you may end up having too many unused connections to the database if you leave the closing up to modlua. Essentially, the following two measures are the same:

-- Method 1: Manually close a handle local database = r:dbacquire("moddbd") database:close() -- All done -- Method 2: Letting the garbage collector close it local database = r:dbacquire("moddbd") database = nil -- throw away the reference collectgarbage() -- close the handle via GC

functions are freely available, it is recommended that you use prepared statements whenever possible, to both optimize performance (if your db handle lives on for a long time) and to minimize the risk of SQL injection attacks. run

should only be used when there are no variables inserted into a statement (a static statement). When using dynamic statements, use db:prepare

LuaAuthzProvider providername /path/to/lua/script.lua functionname

LuaCodeCache stat|forever|never

In general stat or forever is good for production, and stat or never for development.

Add your hook to the accesschecker phase. An access checker hook function usually returns OK, DECLINED, or HTTPFORBIDDEN.

require 'apache2' -- fake authcheck hook -- If request has no auth info, set the response header and -- return a 401 to ask the browser for basic auth info. -- If request has auth info, don't actually look at it, just -- pretend we got userid 'foo' and validated it. -- Then check if the userid is 'foo' and accept the request. function authcheckhook(r) -- look for auth info auth = r.headersin['Authorization'] if auth ~= nil then -- fake the user r.user = 'foo' end if r.user == nil then r:debug("authcheck: user is nil, returning 401") r.errheadersout['WWW-Authenticate'] = 'Basic realm="WallyWorld"' return 401 elseif r.user == "foo" then r:debug('user foo: OK') else r:debug("authcheck: user='" .. r.user .. "'") r.errheadersout['WWW-Authenticate'] = 'Basic realm="WallyWorld"' return 401 end return apache2.OK end

to tell httpd to log as normal.

-- /path/to/script.lua -- function logger(r) -- flip a coin: -- If 1, then we write to our own Lua log and tell httpd not to log -- in the main log. -- If 2, then we just sanitize the output a bit and tell httpd to -- log the sanitized bits. if math.random(1,2) == 1 then -- Log stuff ourselves and don't log in the regular log local f = io.open("/foo/secret.log", "a") if f then f:write("Something secret happened at " .. r.uri .. "\n") f:close() end return apache2.DONE -- Tell httpd not to use the regular logging functions else r.uri = r.uri:gsub("somesecretstuff", "") -- sanitize the URI return apache2.OK -- tell httpd to log it. end end

require"apache2" cachedfiles = {} function readfile(filename) local input = io.open(filename, "r") if input then local data = input:read("*a") cachedfiles[filename] = data file = cachedfiles[filename] input:close() end return cachedfiles[filename] end function checkcache(r) if r.filename:match("%.png$") then -- Only match PNG files local file = cachedfiles[r.filename] -- Check cache entries if not file then file = readfile(r.filename) -- Read file into cache end if file then -- If file exists, write it out r.status = 200 r:write(file) r:info(("Sent %s to client from cache"):format(r.filename)) return apache2.DONE -- skip default handler for PNG files end end return apache2.DECLINED -- If we had nothing to do, let others serve this. end

For those new to hooks, basically each hook will be invoked until one of them returns apache2.OK. If your hook doesn't want to do the translation it should just return apache2.DECLINED. If the request should stop processing, then return apache2.DONE.

function typechecker(r) if r.uri:match("%.togif$") then -- match foo.png.togif r.contenttype = "image/gif" -- assign it the image/gif type r.handler = "gifWizard" -- tell the gifWizard module to handle this r.filename = r.uri:gsub("%.to_gif$", "") -- fix the filename requested return apache2.OK end return apache2.DECLINED end

In previous 2.3.x releases, the default was effectively to ignore LuaHook* directives from parent configuration sections.

LuaInputFilter myInputFilter /www/filter.lua input_filter SetInputFilter myInputFilter

--[[ Example input filter that converts all POST data to uppercase. ]]-- function input_filter(r) print("luaInputFilter called") -- debug print coroutine.yield() -- Yield and wait for buckets while bucket do -- For each bucket, do... local output = string.upper(bucket) -- Convert all POST data to uppercase coroutine.yield(output) -- Send converted data down the chain end -- No more buckets available. coroutine.yield("&filterSignature=1234") -- Append signature at the end end

The input filter supports denying/skipping a filter if it is deemed unwanted:

function input_filter(r) if not good then return -- Simply deny filtering, passing on the original content instead end coroutine.yield() -- wait for buckets ... -- insert filter stuff here end

This would match uri's such as /photos/show?id=9 to the file /scripts/photos.lua and invoke the handler function handle_show on the lua vm after loading that file.

LuaMapHandler /bingo /scripts/wombat.lua

LuaOutputFilter myOutputFilter /www/filter.lua output_filter SetOutputFilter myOutputFilter

--[[ Example output filter that escapes all HTML entities in the output ]]-- function outputfilter(r) coroutine.yield("(Handled by myOutputFilter)
\n") -- Prepend some data to the output, -- yield and wait for buckets. while bucket do -- For each bucket, do... local output = r:escapehtml(bucket) -- Escape all output coroutine.yield(output) -- Send converted data down the chain end -- No more buckets available. end

directive, filtering will only work when the FilterProviderfilter-name is identical to the provider-name.

are void in this phase, just as URIs have not been properly parsed yet.

LuaScope once|request|conn|thread|server [min] [max]

arguments specify the minimum and maximum number of Lua states to keep in the pool. Generally speaking, the thread

scopes execute roughly 2-3 times faster than the rest, because they don't have to spawn new Lua states on every request (especially with the event MPM, as even keepalive requests will use a new thread for each request). If you are satisfied that your scripts will not have problems reusing a state, then the thread

scope will provide the fastest responses, the server

scope will use less memory, as states are pooled, allowing f.x. 1000 threads to share only 100 Lua states, thus using only 10% of the memory required by the thread

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