ts-lua Plugin

This module embeds Lua, via the standard Lua 5.1 interpreter, into Apache Traffic Server. With this module, we can implement ATS plugin by writing lua script instead of c code. Lua code executed using this module can be 100% non-blocking because the powerful Lua coroutines had been integrated in to ATS event model.

Synopsis

test_hdr.lua

function send_response()
    ts.client_response.header['Rhost'] = ts.ctx['rhost']
    return 0
end

function do_remap()
    local req_host = ts.client_request.header.Host
    ts.ctx['rhost'] = string.reverse(req_host)
    ts.hook(TS_LUA_HOOK_SEND_RESPONSE_HDR, send_response)
    return 0
end

sethost.lua

local HOSTNAME = ''
function __init__(argtb)
    if (#argtb) < 1 then
        print(argtb[0], 'hostname parameter required!!')
        return -1
    end
    HOSTNAME = argtb[1]
end

function do_remap()
    ts.client_request.header['Host'] = HOSTNAME
    return 0
end

Installation

This plugin is only built if the configure option

--enable-experimental-plugins

is given at build time.

Configuration

This module acts as remap plugin of Traffic Server, so we should realize ‘do_remap’ function in each lua script. We can write this in remap.config:

map http://a.tbcdn.cn/ http://inner.tbcdn.cn/ @plugin=/XXX/tslua.so @pparam=/XXX/test_hdr.lua

Sometimes we want to receive parameters and process them in the script, we should realize ‘__init__’ function in the lua script, and we can write this in remap.config:

map http://a.x.cn/ http://b.x.cn/ @plugin=/X/tslua.so @pparam=/X/sethost.lua @pparam=a.st.cn

This module can also act as a global plugin of Traffic Server. In this case we should provide one of these functions in each lua script:

  • ‘do_global_txn_start’
  • ‘do_global_txn_close’
  • ‘do_global_os_dns’
  • ‘do_global_pre_remap’
  • ‘do_global_post_remap’
  • ‘do_global_read_request’
  • ‘do_global_send_request’
  • ‘do_global_read_response’
  • ‘do_global_send_response’
  • ‘do_global_cache_lookup_complete’
  • ‘do_global_read_cache’
  • ‘do_global_select_alt’

We can write this in plugin.config:

tslua.so /etc/trafficserver/script/test_global_hdr.lua

TS API for Lua

Introduction

The API is exposed to Lua in the form of one standard packages ts. This package is in the default global scope and is always available within lua script. This package can be introduced into Lua like this:

ts.say('Hello World')
ts.sleep(10)

TOP

ts.now

syntax: val = ts.now()

context: global

description: This function returns the time since the Epoch (00:00:00 UTC, January 1, 1970), measured in seconds.

Here is an example:

local nt = ts.now()  -- 1395221053

TOP

ts.debug

syntax: ts.debug(MESSAGE)

context: global

description: Log the MESSAGE to traffic.out if debug is enabled.

Here is an example:

ts.debug('I am in do_remap now.')

The debug tag is ts_lua and we should write this in records.config:

CONFIG proxy.config.diags.debug.tags STRING ts_lua

TOP

Remap status constants

context: do_remap

TS_LUA_REMAP_NO_REMAP (0)
TS_LUA_REMAP_DID_REMAP (1)
TS_LUA_REMAP_NO_REMAP_STOP (2)
TS_LUA_REMAP_DID_REMAP_STOP (3)
TS_LUA_REMAP_ERROR (-1)

These constants are usually used as return value of do_remap function.

TOP

ts.hook

syntax: ts.hook(HOOK_POINT, FUNCTION)

context: global or do_remap or do_global_* or later

description: Hooks are points in http transaction processing where we can step in and do some work. FUNCTION will be called when the http transaction steps in to HOOK_POINT.

Here is an example

function send_response()
    s.client_response.header['SHE'] = 'belief'
end

function do_remap()
    ts.hook(TS_LUA_HOOK_SEND_RESPONSE_HDR, send_response)
end

Then the client will get the response like this:

HTTP/1.1 200 OK
Content-Type: text/html
Server: ATS/3.2.0
SHE: belief
Connection: Keep-Alive
...

You can create global hook as well

function do_some_work()
   ts.debug('do_some_work')
   return 0
end

ts.hook(TS_LUA_HOOK_READ_REQUEST_HDR, do_some_work)

Or you can do it this way

ts.hook(TS_LUA_HOOK_READ_REQUEST_HDR,
function()
ts.debug(‘do_some_work’) return 0

end

)

Also the return value of the function will control how the transaction will be re-enabled. Return value of 0 will cause the transaction to be re-enabled normally (TS_EVENT_HTTP_CONTINUE). Return value of 1 will be using TS_EVENT_HTTP_ERROR instead.

TOP

Hook point constants

context: do_remap or later

TS_LUA_HOOK_OS_DNS
TS_LUA_HOOK_PRE_REMAP
TS_LUA_HOOK_READ_CACHE_HDR
TS_LUA_HOOK_SELECT_ALT
TS_LUA_HOOK_TXN_CLOSE
TS_LUA_HOOK_POST_REMAP
TS_LUA_HOOK_CACHE_LOOKUP_COMPLETE
TS_LUA_HOOK_READ_REQUEST_HDR
TS_LUA_HOOK_SEND_REQUEST_HDR
TS_LUA_HOOK_READ_RESPONSE_HDR
TS_LUA_HOOK_SEND_RESPONSE_HDR
TS_LUA_REQUEST_TRANSFORM
TS_LUA_RESPONSE_TRANSFORM

These constants are usually used in ts.hook method call.

TOP

ts.ctx

syntax: ts.ctx[KEY] = VALUE

syntax: VALUE = ts.ctx[KEY]

context: do_remap or do_global_* or later

description: This table can be used to store per-request Lua context data and has a life time identical to the current request.

Here is an example:

function send_response()
    ts.client_response.header['F-Header'] = ts.ctx['hdr']
    return 0
end

function do_remap()
    ts.ctx['hdr'] = 'foo'
    ts.hook(TS_LUA_HOOK_SEND_RESPONSE_HDR, send_response)
    return 0
end

Then the client will get the response like this:

HTTP/1.1 200 OK
Content-Type: text/html
Server: ATS/3.2.0
F-Header: foo
Connection: Keep-Alive
...

TOP

ts.client_request.get_method

syntax: ts.client_request.get_method()

context: do_remap or do_global_* or later

description: This function can be used to retrieve the current client request’s method name. String like “GET” or “POST” is returned.

TOP

ts.client_request.set_method

syntax: ts.client_request.set_method()

context: do_remap or do_global_*

description: This function can be used to override the current client request’s method with METHOD_NAME.

ts.client_request.get_version

syntax: ver = ts.client_request.get_version()

context: do_remap or do_global_* or later

description: Return the http version string of the client request.

Current possible values are 1.0, 1.1, and 0.9.

TOP

ts.client_request.set_version

syntax: ts.client_request.set_version(VERSION_STR)

context: do_remap or do_global_* or later

description: Set the http version of the client request with the VERSION_STR

ts.client_request.set_version('1.0')

TOP

ts.client_request.get_uri

syntax: ts.client_request.get_uri()

context: do_remap or later

description: This function can be used to retrieve the client request’s path.

Here is an example:

function do_remap()
    local uri = ts.client_request.get_uri()
    print(uri)
end

Then GET /st?a=1 will yield the output:

/st

TOP

ts.client_request.set_uri

syntax: ts.client_request.set_uri(PATH)

context: do_remap or do_global_*

description: This function can be used to override the client request’s path.

The PATH argument must be a Lua string and starts with /

TOP

ts.client_request.get_uri_args

syntax: ts.client_request.get_uri_args()

context: do_remap or do_global_* or later

description: This function can be used to retrieve the client request’s query string.

Here is an example:

function do_remap()
    local query = ts.client_request.get_uri_args()
    print(query)
end

Then GET /st?a=1&b=2 will yield the output:

a=1&b=2

TOP

ts.client_request.set_uri_args

syntax: ts.client_request.set_uri_args(QUERY_STRING)

context: do_remap or do_global_*

description: This function can be used to override the client request’s query string.

ts.client_request.set_uri_args('n=6&p=7')

TOP

ts.client_request.get_url

syntax: ts.client_request.get_url()

context: do_remap or do_global_* or later

description: This function can be used to retrieve the whole client request’s url.

Here is an example:

function do_remap()
    local url = ts.client_request.get_url()
    print(url)
end

Then GET /st?a=1&b=2 HTTP/1.1\r\nHost: a.tbcdn.cn\r\n... will yield the output:

http://a.tbcdn.cn/st?a=1&b=2

TOP

ts.client_request.header.HEADER

syntax: ts.client_request.header.HEADER = VALUE

syntax: ts.client_request.header[HEADER] = VALUE

syntax: VALUE = ts.client_request.header.HEADER

context: do_remap or do_global_* or later

description: Set, add to, clear or get the current client request’s HEADER.

Here is an example:

function do_remap()
    local ua = ts.client_request.header['User-Agent']
    print(ua)
    ts.client_request.header['Host'] = 'a.tbcdn.cn'
end

Then GET /st HTTP/1.1\r\nHost: b.tb.cn\r\nUser-Agent: Mozilla/5.0\r\n... will yield the output:

Mozilla/5.0

TOP

ts.client_request.get_headers

syntax: ts.client_request.get_headers()

context: do_remap or do_global_* or later

description: Returns a Lua table holding all the headers for the current client request.

Here is an example:

function do_remap()
    hdrs = ts.client_request.get_headers()
    for k, v in pairs(hdrs) do
        print(k..': '..v)
    end
end

Then GET /st HTTP/1.1\r\nHost: b.tb.cn\r\nUser-Aget: Mozilla/5.0\r\nAccept: */* will yield the output

Host: b.tb.cn
User-Agent: Mozilla/5.0
Accept: */*

TOP

ts.client_request.client_addr.get_addr

syntax: ts.client_request.client_addr.get_addr()

context: do_remap or do_global_* or later

description: This function can be used to get socket address of the client.

The ts.client_request.client_addr.get_addr function returns three values, ip is a string, port and family is number.

Here is an example:

function do_remap()
    ip, port, family = ts.client_request.client_addr.get_addr()
    print(ip)               -- 192.168.231.17
    print(port)             -- 17786
    print(family)           -- 2(AF_INET)
    return 0
end

TOP

ts.client_request.get_url_host

syntax: host = ts.client_request.get_url_host()

context: do_remap or do_global_* or later

description: Return the host field of the request url.

Here is an example:

function do_remap()
    local url_host = ts.client_request.get_url_host()
    print(url_host)
end

Then GET /liuyurou.txt HTTP/1.1\r\nHost: 192.168.231.129:8080\r\n... will yield the output:

192.168.231.129

TOP

ts.client_request.set_url_host

syntax: ts.client_request.set_url_host(str)

context: do_remap or do_global_*

description: Set host field of the request url with str. This function is used to change the address of the origin server, and we should return TS_LUA_REMAP_DID_REMAP(_STOP) in do_remap.

Here is an example:

function do_remap()
    ts.client_request.set_url_host('192.168.231.130')
    ts.client_request.set_url_port(80)
    ts.client_request.set_url_scheme('http')
    return TS_LUA_REMAP_DID_REMAP
end

remap.config like this:

map http://192.168.231.129:8080/ http://192.168.231.129:9999/

Then server request will connect to 192.168.231.130:80

TOP

ts.client_request.get_url_port

syntax: port = ts.client_request.get_url_port()

context: do_remap or do_global_* or later

description: Returns the port field of the request url as a Lua number.

Here is an example:

function do_remap()
    local url_port = ts.client_request.get_url_port()
    print(url_port)
end

Then Then GET /liuyurou.txt HTTP/1.1\r\nHost: 192.168.231.129:8080\r\n... will yield the output:

8080

TOP

ts.client_request.set_url_port

syntax: ts.client_request.set_url_port(NUMBER)

context: do_remap or do_global_*

description: Set port field of the request url with NUMBER. This function is used to change the address of the origin server, and we should return TS_LUA_REMAP_DID_REMAP(_STOP) in do_remap.

TOP

ts.client_request.get_url_scheme

syntax: scheme = ts.client_request.get_url_scheme()

context: do_remap or do_global_* or later

description: Return the scheme field of the request url.

Here is an example:

function do_remap()
    local url_scheme = ts.client_request.get_url_scheme()
    print(url_scheme)
end

Then GET /liuyurou.txt HTTP/1.1\r\nHost: 192.168.231.129:8080\r\n... will yield the output:

http

TOP

ts.client_request.set_url_scheme

syntax: ts.client_request.set_url_scheme(str)

context: do_remap or do_global_*

description: Set scheme field of the request url with str. This function is used to change the scheme of the server request, and we should return TS_LUA_REMAP_DID_REMAP(_STOP) in do_remap.

TOP

ts.http.set_cache_url

syntax: ts.http.set_cache_url(KEY_URL)

context: do_remap or do_global_*

description: This function can be used to modify the cache key for the client request.

Here is an example:

function do_remap()
    ts.http.set_cache_url('http://a.tbcdn.cn/foo')
    return 0
end

TOP

ts.http.set_resp

syntax: ts.http.set_resp(CODE, BODY)

context: do_remap or do_global_*

description: This function can be used to set response for the client with the CODE status and BODY string.

Here is an example:

function do_remap()
    ts.http.set_resp(403, "Document access failed :)\n")
    return 0
end

We will get the response like this:

HTTP/1.1 403 Forbidden
Date: Thu, 20 Mar 2014 06:12:43 GMT
Connection: close
Server: ATS/5.0.0
Cache-Control: no-store
Content-Type: text/html
Content-Language: en
Content-Length: 27

Document access failed :)

TOP

ts.http.get_cache_lookup_status

syntax: ts.http.get_cache_lookup_status()

context: function @ TS_LUA_HOOK_CACHE_LOOKUP_COMPLETE hook point

description: This function can be used to get cache lookup status.

Here is an example:

function cache_lookup()
    local cache_status = ts.http.get_cache_lookup_status()
    if cache_status == TS_LUA_CACHE_LOOKUP_HIT_FRESH then
        print('hit')
    else
        print('not hit')
    end
end

function do_remap()
    ts.hook(TS_LUA_HOOK_CACHE_LOOKUP_COMPLETE, cache_lookup)
    return 0
end

TOP

Http cache lookup status constants

context: global

TS_LUA_CACHE_LOOKUP_MISS (0)
TS_LUA_CACHE_LOOKUP_HIT_STALE (1)
TS_LUA_CACHE_LOOKUP_HIT_FRESH (2)
TS_LUA_CACHE_LOOKUP_SKIPPED (3)

TOP

ts.cached_response.get_status

syntax: status = ts.cached_response.get_status()

context: function @ TS_LUA_HOOK_CACHE_LOOKUP_COMPLETE hook point or later

description: This function can be used to retrieve the status code of the cached response. A Lua number will be returned.

Here is an example:

function cache_lookup()
    local cache_status = ts.http.get_cache_lookup_status()
    if cache_status == TS_LUA_CACHE_LOOKUP_HIT_FRESH then
        code = ts.cached_response.get_status()
        print(code)         -- 200
    end
end

function do_remap()
    ts.hook(TS_LUA_HOOK_CACHE_LOOKUP_COMPLETE, cache_lookup)
    return 0
end

TOP

ts.cached_response.get_version

syntax: ver = ts.cached_response.get_version()

context: function @ TS_LUA_HOOK_CACHE_LOOKUP_COMPLETE hook point or later

description: Return the http version string of the cached response.

Current possible values are 1.0, 1.1, and 0.9.

TOP

ts.cached_response.header.HEADER

syntax: VALUE = ts.cached_response.header.HEADER

syntax: VALUE = ts.cached_response.header[HEADER]

context: function @ TS_LUA_HOOK_CACHE_LOOKUP_COMPLETE hook point or later

description: get the current cached response’s HEADER.

Here is an example:

function cache_lookup()
    local status = ts.http.get_cache_lookup_status()
    if status == TS_LUA_CACHE_LOOKUP_HIT_FRESH then
        local ct = ts.cached_response.header['Content-Type']
        print(ct)         -- text/plain
    end
end

function do_remap()
    ts.hook(TS_LUA_HOOK_CACHE_LOOKUP_COMPLETE, cache_lookup)
    return 0
end

TOP

ts.cached_response.get_headers

syntax: ts.cached_response.get_headers()

context: function @ TS_LUA_HOOK_CACHE_LOOKUP_COMPLETE hook point or later

description: Returns a Lua table holding all the headers for the current cached response.

Here is an example:

function cache_lookup()
    local status = ts.http.get_cache_lookup_status()
    if status == TS_LUA_CACHE_LOOKUP_HIT_FRESH then
        hdrs = ts.cached_response.get_headers()
        for k, v in pairs(hdrs) do
            print(k..': '..v)
        end
    end
end

function do_remap()
    ts.hook(TS_LUA_HOOK_CACHE_LOOKUP_COMPLETE, cache_lookup)
    return 0
end

We will get the output:

Connection: keep-alive
Content-Type: text/plain
Date: Thu, 20 Mar 2014 06:12:20 GMT
Cache-Control: max-age=864000
Last-Modified: Sun, 19 May 2013 13:22:01 GMT
Accept-Ranges: bytes
Content-Length: 15
Server: ATS/5.0.0

TOP

ts.server_request.get_uri

syntax: ts.server_request.get_uri()

context: function @ TS_LUA_HOOK_SEND_REQUEST_HDR hook point or later

description: This function can be used to retrieve the server request’s path.

Here is an example:

function send_request()
    local uri = ts.server_request.get_uri()
    print(uri)
end

function do_remap()
    ts.hook(TS_LUA_HOOK_SEND_REQUEST_HDR, send_request)
    return 0
end

Then GET /am.txt?a=1 will yield the output:

/am.txt

TOP

ts.server_request.set_uri

syntax: ts.server_request.set_uri(PATH)

context: function @ TS_LUA_HOOK_SEND_REQUEST_HDR hook point

description: This function can be used to override the server request’s path.

The PATH argument must be a Lua string and starts with /

TOP

ts.server_request.get_uri_args

syntax: ts.server_request.get_uri_args()

context: function @ TS_LUA_HOOK_SEND_REQUEST_HDR hook point or later

description: This function can be used to retrieve the server request’s query string.

Here is an example:

function send_request()
    local query = ts.server_request.get_uri_args()
    print(query)
end

function do_remap()
    ts.hook(TS_LUA_HOOK_SEND_REQUEST_HDR, send_request)
    return 0
end

Then GET /st?a=1&b=2 will yield the output:

a=1&b=2

TOP

ts.server_request.set_uri_args

syntax: ts.server_request.set_uri_args(QUERY_STRING)

context: function @ TS_LUA_HOOK_SEND_REQUEST_HDR hook point

description: This function can be used to override the server request’s query string.

ts.server_request.set_uri_args('n=6&p=7')

TOP

ts.server_request.header.HEADER

syntax: ts.server_request.header.HEADER = VALUE

syntax: ts.server_request.header[HEADER] = VALUE

syntax: VALUE = ts.server_request.header.HEADER

context: function @ TS_LUA_HOOK_SEND_REQUEST_HDR hook point or later

description: Set, add to, clear or get the current server request’s HEADER.

Here is an example:

function send_request()
    local ua = ts.server_request.header['User-Agent']
    print(ua)
    ts.server_request.header['Accept-Encoding'] = 'gzip'
end

function do_remap()
    ts.hook(TS_LUA_HOOK_SEND_REQUEST_HDR, send_request)
    return 0
end

Then GET /st HTTP/1.1\r\nHost: b.tb.cn\r\nUser-Agent: Mozilla/5.0\r\n... will yield the output:

Mozilla/5.0

TOP

ts.server_request.get_headers

syntax: ts.server_request.get_headers()

context: function @ TS_LUA_HOOK_SEND_REQUEST_HDR hook point or later

description: Returns a Lua table holding all the headers for the current server request.

Here is an example:

function send_request()
    hdrs = ts.cached_response.get_headers()
    for k, v in pairs(hdrs) do
        print(k..': '..v)
    end
end

function do_remap()
    ts.hook(TS_LUA_HOOK_SEND_REQUEST_HDR, send_request)
    return 0
end

We will get the output:

Host: b.tb.cn
User-Agent: curl/7.19.7
Accept: */*

TOP

ts.server_response.get_status

syntax: status = ts.server_response.get_status()

context: function @ TS_LUA_HOOK_READ_RESPONSE_HDR hook point or later

description: This function can be used to retrieve the status code of the origin server’s response. A Lua number will be returned.

Here is an example:

function read_response()
    local code = ts.server_response.get_status()
    print(code)         -- 200
end

function do_remap()
    ts.hook(TS_LUA_HOOK_READ_RESPONSE_HDR, read_response)
    return 0
end

TOP‘

ts.server_response.set_status

syntax: ts.server_response.set_status(NUMBER)

context: function @ TS_LUA_HOOK_READ_RESPONSE_HDR hook point

description: This function can be used to set the status code of the origin server’s response.

Here is an example:

function read_response()
    ts.server_response.set_status(404)
end

function do_remap()
    ts.hook(TS_LUA_HOOK_READ_RESPONSE_HDR, read_response)
    return 0
end

TOP‘

ts.server_response.get_version

syntax: ver = ts.server_response.get_version()

context: function @ TS_LUA_HOOK_READ_RESPONSE_HDR hook point or later.

description: Return the http version string of the server response.

Current possible values are 1.0, 1.1, and 0.9.

TOP

ts.server_response.set_version

syntax: ts.server_response.set_version(VERSION_STR)

context: function @ TS_LUA_HOOK_READ_RESPONSE_HDR hook point

description: Set the http version of the server response with the VERSION_STR

ts.server_response.set_version('1.0')

TOP

ts.server_response.header.HEADER

syntax: ts.server_response.header.HEADER = VALUE

syntax: ts.server_response.header[HEADER] = VALUE

syntax: VALUE = ts.server_response.header.HEADER

context: function @ TS_LUA_HOOK_READ_RESPONSE_HDR hook point or later.

description: Set, add to, clear or get the current server response’s HEADER.

Here is an example:

function read_response()
    local ct = ts.server_response.header['Content-Type']
    print(ct)
    ts.server_response.header['Cache-Control'] = 'max-age=14400'
end

function do_remap()
    ts.hook(TS_LUA_HOOK_READ_RESPONSE_HDR, read_response)
    return 0
end

We will get the output:

text/html

TOP‘

ts.server_response.get_headers

syntax: ts.server_response.get_headers()

context: function @ TS_LUA_HOOK_READ_RESPONSE_HDR hook point or later

description: Returns a Lua table holding all the headers for the current server response.

Here is an example:

function read_response()
    hdrs = ts.server_response.get_headers()
    for k, v in pairs(hdrs) do
        print(k..': '..v)
    end
end

function do_remap()
    ts.hook(TS_LUA_HOOK_READ_RESPONSE_HDR, read_response)
    return 0
end

We will get the output:

Server: nginx/1.5.9
Date: Tue, 18 Mar 2014 10:12:25 GMT
Content-Type: text/html
Content-Length: 555
Last-Modified: Mon, 19 Aug 2013 14:25:55 GMT
Connection: keep-alive
ETag: "52122af3-22b"
Cache-Control: max-age=14400
Accept-Ranges: bytes

TOP

ts.client_response.get_status

syntax: status = ts.client_response.get_status()

context: function @ TS_LUA_HOOK_SEND_RESPONSE_HDR hook point

description: This function can be used to retrieve the status code of the response to the client. A Lua number will be returned.

Here is an example:

function send_response()
    local code = ts.client_response.get_status()
    print(code)         -- 200
end

function do_remap()
    ts.hook(TS_LUA_HOOK_SEND_RESPONSE_HDR, send_response)
    return 0
end

TOP

ts.client_response.set_status

syntax: ts.client_response.set_status(NUMBER)

context: function @ TS_LUA_HOOK_SEND_RESPONSE_HDR hook point

description: This function can be used to set the status code of the response to the client.

Here is an example:

function send_response()
    ts.client_response.set_status(404)
end

function do_remap()
    ts.hook(TS_LUA_HOOK_SEND_RESPONSE_HDR, send_response)
    return 0
end

TOP

ts.client_response.get_version

syntax: ver = ts.client_response.get_version()

context: function @ TS_LUA_HOOK_SEND_RESPONSE_HDR hook point.

description: Return the http version string of the response to the client.

Current possible values are 1.0, 1.1, and 0.9.

TOP

ts.client_response.set_version

syntax: ts.client_response.set_version(VERSION_STR)

context: function @ TS_LUA_HOOK_SEND_RESPONSE_HDR hook point

description: Set the http version of the response to the client with the VERSION_STR

ts.client_response.set_version('1.0')

TOP

ts.client_response.header.HEADER

syntax: ts.client_response.header.HEADER = VALUE

syntax: ts.client_response.header[HEADER] = VALUE

syntax: VALUE = ts.client_response.header.HEADER

context: function @ TS_LUA_HOOK_SEND_RESPONSE_HDR hook point.

description: Set, add to, clear or get the current client response’s HEADER.

Here is an example:

function send_response()
    local ct = ts.client_response.header['Content-Type']
    print(ct)
    ts.client_response.header['Cache-Control'] = 'max-age=3600'
end

function do_remap()
    ts.hook(TS_LUA_HOOK_SEND_RESPONSE_HDR, send_response)
    return 0
end

We will get the output:

text/html

TOP

ts.client_response.get_headers

syntax: ts.client_response.get_headers()

context: function @ TS_LUA_HOOK_SEND_RESPONSE_HDR hook point.

description: Returns a Lua table holding all the headers for the current client response.

Here is an example:

function send_response()
    hdrs = ts.client_response.get_headers()
    for k, v in pairs(hdrs) do
        print(k..': '..v)
    end
end

function do_remap()
    ts.hook(TS_LUA_HOOK_SEND_RESPONSE_HDR, send_response)
    return 0
end

We will get the output:

Server: ATS/5.0.0
Date: Tue, 18 Mar 2014 10:12:25 GMT
Content-Type: text/html
Transfer-Encoding: chunked
Last-Modified: Mon, 19 Aug 2013 14:25:55 GMT
Connection: keep-alive
Cache-Control: max-age=14400
Age: 2641
Accept-Ranges: bytes

TOP

ts.client_response.set_error_resp

syntax: ts.client_response.set_error_resp(CODE, BODY)

context: function @ TS_LUA_HOOK_SEND_RESPONSE_HDR hook point.

description: This function can be used to set the error response to the client.

With this function we can jump to send error response to the client if exception exists, meanwhile we should return -1 from the function where exception raises.

Here is an example:

function send_response()
    ts.client_response.set_error_resp(404, 'bad luck :(\n')
end

function cache_lookup()
    return -1
end

function do_remap()
    ts.hook(TS_LUA_HOOK_CACHE_LOOKUP_COMPLETE, cache_lookup)
    ts.hook(TS_LUA_HOOK_SEND_RESPONSE_HDR, send_response)
    return 0
end

We will get the response like this:

HTTP/1.1 404 Not Found
Date: Tue, 18 Mar 2014 11:16:00 GMT
Connection: keep-alive
Server: ATS/5.0.0
Content-Length: 12

bad luck :(

TOP

ts.http.resp_cache_transformed

syntax: ts.http.resp_cache_transformed(BOOL)

context: do_remap or do_global_* or later

description: This function can be used to tell trafficserver whether to cache the transformed data.

Here is an example:

function upper_transform(data, eos)
    if eos == 1 then
        return string.upper(data)..'S.H.E.\n', eos
    else
        return string.upper(data), eos
    end
end

function do_remap()
    ts.hook(TS_LUA_RESPONSE_TRANSFORM, upper_transform)
    ts.http.resp_cache_transformed(0)
    return 0
end

This function is usually called after we hook TS_LUA_RESPONSE_TRANSFORM.

TOP

ts.http.resp_cache_untransformed

syntax: ts.http.resp_cache_untransformed(BOOL)

context: do_remap or do_global_* or later

description: This function can be used to tell trafficserver whether to cache the untransformed data.

Here is an example:

function upper_transform(data, eos)
    if eos == 1 then
        return string.upper(data)..'S.H.E.\n', eos
    else
        return string.upper(data), eos
    end
end

function do_remap()
    ts.hook(TS_LUA_RESPONSE_TRANSFORM, upper_transform)
    ts.http.resp_cache_untransformed(1)
    return 0
end

This function is usually called after we hook TS_LUA_RESPONSE_TRANSFORM.

TOP

ts.http.skip_remapping_set

syntax: ts.http.skip_remapping_set(BOOL)

context: do_global_read_request

description: This function can be used to tell trafficserver to skip doing remapping

Here is an example:

function do_global_read_request()
    ts.http.skip_remapping_set(1);
    ts.client_request.header['Host'] = 'www.yahoo.com'
    return 0
end

This function is usually called in do_global_read_request function

ts.http.is_internal_request

syntax: ts.http.is_internal_request()

** context:** do_remap or do_global_* or later

** description**: This function can be used to tell is a request is internal or not

Here is an example:

function do_global_read_request()
    local internal = ts.http.is_internal_request()
    ts.debug(internal)
    return 0
end

ts.add_package_path

syntax: ts.add_package_path(lua-style-path-str)

context: init stage of the lua script

description: Adds the Lua module search path used by scripts.

The path string is in standard Lua path form.

Here is an example:

ts.add_package_path('/home/a/test/lua/pac/?.lua')
local nt = require("nt")
function do_remap()
    print(nt.t9(7979))
    return 0
end

TOP

ts.add_package_cpath

syntax: ts.add_package_cpath(lua-style-cpath-str)

context: init stage of the lua script

description: Adds the Lua C-module search path used by scripts.

The cpath string is in standard Lua cpath form.

Here is an example:

ts.add_package_cpath('/home/a/test/c/module/?.so')
local ma = require("ma")
function do_remap()
    print(ma.ft())
    return 0
end

TOP

ts.md5

syntax: digest = ts.md5(str)

context: global

description: Returns the hexadecimal representation of the MD5 digest of the str argument.

Here is an example:

function do_remap()
    uri = ts.client_request.get_uri()
    print(uri)              -- /foo
    print(ts.md5(uri))      -- 1effb2475fcfba4f9e8b8a1dbc8f3caf
end

TOP

ts.md5_bin

syntax: digest = ts.md5_bin(str)

context: global

description: Returns the binary form of the MD5 digest of the str argument.

Here is an example:

function do_remap()
    uri = ts.client_request.get_uri()
    bin = ts.md5_bin(uri)
end

TOP

ts.sha1

syntax: digest = ts.sha1(str)

context: global

description: Returns the hexadecimal representation of the SHA-1 digest of the str argument.

Here is an example:

function do_remap()
    uri = ts.client_request.get_uri()
    print(uri)              -- /foo
    print(ts.sha1(uri))     -- 6dbd548cc03e44b8b44b6e68e56255ce4273ae49
end

TOP

ts.sha1_bin

syntax: digest = ts.sha1_bin(str)

context: global

description: Returns the binary form of the SHA-1 digest of the str argument.

Here is an example:

function do_remap()
    uri = ts.client_request.get_uri()
    bin = ts.sha1_bin(uri)
end

TOP

ts.intercept

syntax: ts.intercept(FUNCTION)

context: do_remap or do_global_*

description: Intercepts the client request and processes it in FUNCTION.

We should construct the response for the client request, and the request will not be processed by other modules, like hostdb, cache, origin server...

Here is an example:

require 'os'

function send_data()
    local nt = os.time()..' Zheng.\n'
    local resp =  'HTTP/1.0 200 OK\r\n' ..
                  'Server: ATS/3.2.0\r\n' ..
                  'Content-Type: text/plain\r\n' ..
                  'Content-Length: ' .. string.format('%d', string.len(nt)) .. '\r\n' ..
                  'Last-Modified: ' .. os.date("%a, %d %b %Y %H:%M:%S GMT", os.time()) .. '\r\n' ..
                  'Connection: keep-alive\r\n' ..
                  'Cache-Control: max-age=7200\r\n' ..
                  'Accept-Ranges: bytes\r\n\r\n' ..
                  nt
    ts.say(resp)
end

function do_remap()
    ts.http.intercept(send_data)
    return 0
end

Then we will get the response like this:

HTTP/1.1 200 OK
Server: ATS/5.0.0
Content-Type: text/plain
Content-Length: 18
Last-Modified: Tue, 18 Mar 2014 08:23:12 GMT
Cache-Control: max-age=7200
Accept-Ranges: bytes
Date: Tue, 18 Mar 2014 12:23:12 GMT
Age: 0
Connection: keep-alive

1395145392 Zheng.

TOP

ts.say

syntax: ts.say(data)

context: intercept or server_intercept

description: Write response to ATS within intercept or server_intercept.

TOP

ts.flush

syntax: ts.flush()

context: intercept or server_intercept

description: Flushes the output to ATS within intercept or server_intercept.

In synchronous mode, the function will not return until all output data has been written into the system send buffer. Note that using the Lua coroutine mechanism means that this function does not block the ATS event loop even in the synchronous mode.

Here is an example:

require 'os'

function send_data()
    ss = 'wo ai yu ye hua\n'
    local resp =  'HTTP/1.0 200 OK\r\n' ..
                  'Server: ATS/3.2.0\r\n' ..
                  'Content-Type: text/plain\r\n' ..
                  'Content-Length: ' .. string.format('%d', 5*string.len(ss)) .. '\r\n' ..
                  'Last-Modified: ' .. os.date("%a, %d %b %Y %H:%M:%S GMT", os.time()) .. '\r\n' ..
                  'Connection: keep-alive\r\n' ..
                  'Cache-Control: max-age=7200\r\n' ..
                  'Accept-Ranges: bytes\r\n\r\n'
    ts.say(resp)
    for i=1, 5 do
        ts.say(ss)
        ts.flush()
    end
end

function do_remap()
    ts.http.intercept(send_data)
    return 0
end

We will get the response like this:

HTTP/1.1 200 OK
Server: ATS/5.0.0
Content-Type: text/plain
Content-Length: 80
Last-Modified: Tue, 18 Mar 2014 08:38:29 GMT
Cache-Control: max-age=7200
Accept-Ranges: bytes
Date: Tue, 18 Mar 2014 12:38:29 GMT
Age: 0
Connection: keep-alive

wo ai yu ye hua
wo ai yu ye hua
wo ai yu ye hua
wo ai yu ye hua
wo ai yu ye hua

TOP

ts.sleep

syntax: ts.sleep(sec)

context: intercept or server_intercept

description: Sleeps for the specified seconds without blocking.

Behind the scene, this method makes use of the ATS event model.

Here is an example:

require 'os'

function send_data()
    local nt = os.time()..' Zheng.\n'
    local resp =  'HTTP/1.0 200 OK\r\n' ..
                  'Server: ATS/3.2.0\r\n' ..
                  'Content-Type: text/plain\r\n' ..
                  'Content-Length: ' .. string.format('%d', string.len(nt)) .. '\r\n\r\n' ..
                  nt
    ts.sleep(3)
    ts.say(resp)
end

function do_remap()
    ts.http.intercept(send_data)
    return 0
end

TOP

ts.server_intercept

syntax: ts.server_intercept(FUNCTION)

context: do_remap or do_global_*

description: Intercepts the server request and acts as the origin server.

We should construct the response for the server request, so the request will be processed within FUNCTION in case of miss for the cache lookup.

Here is an example:

require 'os'

function send_data()
    local nt = os.time()..' Zheng.\n'
    local resp =  'HTTP/1.0 200 OK\r\n' ..
                  'Server: ATS/3.2.0\r\n' ..
                  'Content-Type: text/plain\r\n' ..
                  'Content-Length: ' .. string.format('%d', string.len(nt)) .. '\r\n' ..
                  'Last-Modified: ' .. os.date("%a, %d %b %Y %H:%M:%S GMT", os.time()) .. '\r\n' ..
                  'Connection: keep-alive\r\n' ..
                  'Cache-Control: max-age=7200\r\n' ..
                  'Accept-Ranges: bytes\r\n\r\n' ..
                  nt
    ts.say(resp)
end

function do_remap()
    ts.http.server_intercept(send_data)
    return 0
end

Then we will get the response like this:

HTTP/1.1 200 OK
Server: ATS/5.0.0
Content-Type: text/plain
Content-Length: 18
Last-Modified: Tue, 18 Mar 2014 08:23:12 GMT
Cache-Control: max-age=7200
Accept-Ranges: bytes
Date: Tue, 18 Mar 2014 12:23:12 GMT
Age: 1890
Connection: keep-alive

1395145392 Zheng.

TOP

ts.http.config_int_get

syntax: val = ts.http.config_int_get(CONFIG)

context: do_remap or do_global_* or later.

description: Configuration option which has a int value can be retrieved with this function.

val = ts.http.config_int_get(TS_LUA_CONFIG_HTTP_CACHE_HTTP)

TOP

ts.http.config_int_set

syntax: ts.http.config_int_set(CONFIG, NUMBER)

context: do_remap or do_global_* or later.

description: This function can be used to overwrite the configuration options.

Here is an example:

function do_remap()
    ts.http.config_int_set(TS_LUA_CONFIG_HTTP_CACHE_HTTP, 0)    -- bypass the cache processor
    return 0
end

TOP

ts.http.config_float_get

syntax: val = ts.http.config_float_get(CONFIG)

context: do_remap or do_global_* or later.

description: Configuration option which has a float value can be retrieved with this function.

TOP

ts.http.config_float_set

syntax: ts.http.config_float_set(CONFIG, NUMBER)

context: do_remap or do_global_* or later.

description: This function can be used to overwrite the configuration options.

TOP

ts.http.config_string_get

syntax: val = ts.http.config_string_get(CONFIG)

context: do_remap or do_global_* or later.

description: Configuration option which has a string value can be retrieved with this function.

TOP

ts.http.config_string_set

syntax: ts.http.config_string_set(CONFIG, NUMBER)

context: do_remap or do_global_* or later.

description: This function can be used to overwrite the configuration options.

TOP

Http config constants

context: do_remap or do_global_* or later

TS_LUA_CONFIG_URL_REMAP_PRISTINE_HOST_HDR
TS_LUA_CONFIG_HTTP_CHUNKING_ENABLED
TS_LUA_CONFIG_HTTP_NEGATIVE_CACHING_ENABLED
TS_LUA_CONFIG_HTTP_NEGATIVE_CACHING_LIFETIME
TS_LUA_CONFIG_HTTP_CACHE_WHEN_TO_REVALIDATE
TS_LUA_CONFIG_HTTP_KEEP_ALIVE_ENABLED_IN
TS_LUA_CONFIG_HTTP_KEEP_ALIVE_ENABLED_OUT
TS_LUA_CONFIG_HTTP_KEEP_ALIVE_POST_OUT
TS_LUA_CONFIG_HTTP_SHARE_SERVER_SESSIONS
TS_LUA_CONFIG_NET_SOCK_RECV_BUFFER_SIZE_OUT
TS_LUA_CONFIG_NET_SOCK_SEND_BUFFER_SIZE_OUT
TS_LUA_CONFIG_NET_SOCK_OPTION_FLAG_OUT
TS_LUA_CONFIG_HTTP_FORWARD_PROXY_AUTH_TO_PARENT
TS_LUA_CONFIG_HTTP_ANONYMIZE_REMOVE_FROM
TS_LUA_CONFIG_HTTP_ANONYMIZE_REMOVE_REFERER
TS_LUA_CONFIG_HTTP_ANONYMIZE_REMOVE_USER_AGENT
TS_LUA_CONFIG_HTTP_ANONYMIZE_REMOVE_COOKIE
TS_LUA_CONFIG_HTTP_ANONYMIZE_REMOVE_CLIENT_IP
TS_LUA_CONFIG_HTTP_ANONYMIZE_INSERT_CLIENT_IP
TS_LUA_CONFIG_HTTP_RESPONSE_SERVER_ENABLED
TS_LUA_CONFIG_HTTP_INSERT_SQUID_X_FORWARDED_FOR
TS_LUA_CONFIG_HTTP_SERVER_TCP_INIT_CWND
TS_LUA_CONFIG_HTTP_SEND_HTTP11_REQUESTS
TS_LUA_CONFIG_HTTP_CACHE_HTTP
TS_LUA_CONFIG_HTTP_CACHE_CLUSTER_CACHE_LOCAL
TS_LUA_CONFIG_HTTP_CACHE_IGNORE_CLIENT_NO_CACHE
TS_LUA_CONFIG_HTTP_CACHE_IGNORE_CLIENT_CC_MAX_AGE
TS_LUA_CONFIG_HTTP_CACHE_IMS_ON_CLIENT_NO_CACHE
TS_LUA_CONFIG_HTTP_CACHE_IGNORE_SERVER_NO_CACHE
TS_LUA_CONFIG_HTTP_CACHE_CACHE_RESPONSES_TO_COOKIES
TS_LUA_CONFIG_HTTP_CACHE_IGNORE_AUTHENTICATION
TS_LUA_CONFIG_HTTP_CACHE_CACHE_URLS_THAT_LOOK_DYNAMIC
TS_LUA_CONFIG_HTTP_CACHE_REQUIRED_HEADERS
TS_LUA_CONFIG_HTTP_INSERT_REQUEST_VIA_STR
TS_LUA_CONFIG_HTTP_INSERT_RESPONSE_VIA_STR
TS_LUA_CONFIG_HTTP_CACHE_HEURISTIC_MIN_LIFETIME
TS_LUA_CONFIG_HTTP_CACHE_HEURISTIC_MAX_LIFETIME
TS_LUA_CONFIG_HTTP_CACHE_GUARANTEED_MIN_LIFETIME
TS_LUA_CONFIG_HTTP_CACHE_GUARANTEED_MAX_LIFETIME
TS_LUA_CONFIG_HTTP_CACHE_MAX_STALE_AGE
TS_LUA_CONFIG_HTTP_KEEP_ALIVE_NO_ACTIVITY_TIMEOUT_IN
TS_LUA_CONFIG_HTTP_KEEP_ALIVE_NO_ACTIVITY_TIMEOUT_OUT
TS_LUA_CONFIG_HTTP_TRANSACTION_NO_ACTIVITY_TIMEOUT_IN
TS_LUA_CONFIG_HTTP_TRANSACTION_NO_ACTIVITY_TIMEOUT_OUT
TS_LUA_CONFIG_HTTP_TRANSACTION_ACTIVE_TIMEOUT_OUT
TS_LUA_CONFIG_HTTP_ORIGIN_MAX_CONNECTIONS
TS_LUA_CONFIG_HTTP_CONNECT_ATTEMPTS_MAX_RETRIES
TS_LUA_CONFIG_HTTP_CONNECT_ATTEMPTS_MAX_RETRIES_DEAD_SERVER
TS_LUA_CONFIG_HTTP_CONNECT_ATTEMPTS_RR_RETRIES
TS_LUA_CONFIG_HTTP_CONNECT_ATTEMPTS_TIMEOUT
TS_LUA_CONFIG_HTTP_POST_CONNECT_ATTEMPTS_TIMEOUT
TS_LUA_CONFIG_HTTP_DOWN_SERVER_CACHE_TIME
TS_LUA_CONFIG_HTTP_DOWN_SERVER_ABORT_THRESHOLD
TS_LUA_CONFIG_HTTP_CACHE_FUZZ_TIME
TS_LUA_CONFIG_HTTP_CACHE_FUZZ_MIN_TIME
TS_LUA_CONFIG_HTTP_DOC_IN_CACHE_SKIP_DNS
TS_LUA_CONFIG_HTTP_RESPONSE_SERVER_STR
TS_LUA_CONFIG_HTTP_CACHE_HEURISTIC_LM_FACTOR
TS_LUA_CONFIG_HTTP_CACHE_FUZZ_PROBABILITY
TS_LUA_CONFIG_NET_SOCK_PACKET_MARK_OUT
TS_LUA_CONFIG_NET_SOCK_PACKET_TOS_OUT

TOP

ts.http.cntl_get

syntax: val = ts.http.cntl_get(CNTL_TYPE)

context: do_remap or do_global_* or later.

description: This function can be used to retireve the value of control channel.

val = ts.http.cntl_get(TS_LUA_HTTP_CNTL_GET_LOGGING_MODE)

TOP

ts.http.cntl_set

syntax: ts.http.cntl_set(CNTL_TYPE, BOOL)

context: do_remap or do_global_* or later.

description: This function can be used to set the value of control channel.

Here is an example:

function do_remap()
    ts.http.cntl_set(TS_LUA_HTTP_CNTL_SET_LOGGING_MODE, 0)      -- do not log the request
    return 0
end

TOP

Http control channel constants

context: do_remap or do_global_* or later

TS_LUA_HTTP_CNTL_GET_LOGGING_MODE
TS_LUA_HTTP_CNTL_SET_LOGGING_MODE
TS_LUA_HTTP_CNTL_GET_INTERCEPT_RETRY_MODE
TS_LUA_HTTP_CNTL_SET_INTERCEPT_RETRY_MODE

TOP

ts.mgmt.get_counter

syntax: val = ts.mgmt.get_counter(RECORD_NAME)

context: do_remap or do_global_* or later.

description: This function can be used to retrieve the record value which has a counter type.

n = ts.mgmt.get_counter('proxy.process.http.incoming_requests')

TOP

ts.mgmt.get_int

syntax: val = ts.mgmt.get_int(RECORD_NAME)

context: do_remap or do_global_* or later.

description: This function can be used to retrieve the record value which has a int type.

TOP

ts.mgmt.get_float

syntax: val = ts.mgmt.get_float(RECORD_NAME)

context: do_remap or do_global_* or later.

description: This function can be used to retrieve the record value which has a float type.

TOP

ts.mgmt.get_string

syntax: val = ts.mgmt.get_string(RECORD_NAME)

context: do_remap or do_global_* or later.

description: This function can be used to retrieve the record value which has a string type.

name = ts.mgmt.get_string('proxy.config.product_name')

TOP

Todo

Currently when we use ts_lua as a global plugin, each global hook is using a separate lua state for the same transaction. This can be wasteful. Also the state cannot be reused for the same transaction across the global hooks. The alternative will be to use a TXN_START hook to create a lua state first and then add each global hook in the lua script as transaction hook instead. But this will have problem down the road when we need to have multiple plugins to work together in some proper orderings. In the future, we should consider different approach, such as creating and maintaining the lua state in the ATS core.

TOP