# Haproxy 2.0 not support 1.8x lua?

**URL:** <https://discourse.haproxy.org/t/haproxy-2-0-not-support-1-8x-lua/4523>\
**Category:** Help!\
**Created:** [November 20, 2019, 1:41am UTC](https://discourse.haproxy.org/t/haproxy-2-0-not-support-1-8x-lua/4523 "2019-11-20T01:41:09Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![fsfs](https://avatars.discourse-cdn.com/v4/letter/f/c0e974/32.png) [@fsfs](https://discourse.haproxy.org/u/fsfs)\
**Post date:** [November 20, 2019, 1:41am UTC](https://discourse.haproxy.org/t/haproxy-2-0-not-support-1-8x-lua/4523/1 "2019-11-20T01:41:09Z")

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this is work for 1.8.x

version:  
HA-Proxy version 2.0.9 2019/11/15 - [https://haproxy.org/](https://haproxy.org/)

#config

frontend api\_http  
acl api\_check path\_beg -i “/check”  
http-request lua.check\_quth if api\_check

#lua  
---------check\_req  
core.register\_action(“api\_check\_req”, { “http-req” }, function(applet)  
local msg = ‘{“status”:1,“message”:“Could not authenticate you.”}’  
applet.res:send(‘HTTP/1.0 200 OK\r\nContent-Type: application/json\r\nConnection: close\r\n\r\n’…msg)  
applet:done()  
end)

#error  
[ALERT] 323/163943 (1236) : Lua function ‘api\_check\_req’: runtime error: 0 from [C] method ‘send’, /root/hap/api.lua:762 C function line 756.

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<div class="post-metadata">

**Author:** ![capflam](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.haproxy.org/capflam/32/236_2.png) [@capflam](https://discourse.haproxy.org/u/capflam)\
**Post date:** [November 21, 2019, 3:15pm UTC](https://discourse.haproxy.org/t/haproxy-2-0-not-support-1-8x-lua/4523/2 "2019-11-21T15:15:10Z")

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There are 2 problems with this lua script. First, the parameter of a lua action is a transaction not an applet. It is just a naming error but it may mislead you. Second, since HAProxy 1.9, it is explicitly forbidden to call some channel’s functions from HTTP actions. Following functions are concerned: `Channel.get`, `Channel.dup`, `Channel.getline`, `Channel.set`, `Channel.append`, `Channel.send`, `Channel.forward`. It was a serious bugs of previous versions. These functions were totally hijacking the internal HTTP parser, leaving it in an undefined state. It was working by chance.

For now, there is no `return` statement in lua (Note there is no such statement either in http rules). And there is no way to deny or redirect a request from the lua itself. So I can see 2 solutions to send a custom reply from HAProxy.

- If the response is static, you store it in an error file with the code 200. And, you may set a variable from your lua action to check it in an acl to deny the request with a deny\_status set to 200. If your lua action does nothing except returning a custom response, you may consider to use the `monitor-uri` directive.

```auto
#config
frontend api_http
    errorfile 200 /path/to/200.http

    http-request lua.check_auth if { path_beg -i /checks }
    http-request deny deny_status 200 if { var(req.blocked) -m bool }

#lua
core.register_action(“api_check_req”, { “http-req” }, function(txn)
    ...
    txn.set-var('req.blocked', true)
end)

```

- If your response must be customized, or if your script is too complex to be reduced to a variable at the end, you may use a lua service. So, here, definitely, there is a documentation problem, because it is an undocumented feature. Note that a service is an endpoint. So you MUST send a response from it. But here is your example with a lua service:

```auto
#config
frontend api_http
    http-request use-service api_check_service if { path_beg -i /checks }

#lua
core.register_service("api_check_service", "http", function(applet)
    local msg = ‘{“status”:1,“message”:“Could not authenticate you.”}’
    applet:set_status(200)
    applet:add_header("content-length", string.len(msg))
    applet:add_header("content-type", "application/json")
    applet:start_response()
    applet:send(response)
end)

```

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<div class="post-metadata">

**Author:** ![fsfs](https://avatars.discourse-cdn.com/v4/letter/f/c0e974/32.png) [@fsfs](https://discourse.haproxy.org/u/fsfs)\
**Post date:** [November 21, 2019, 9:06pm UTC](https://discourse.haproxy.org/t/haproxy-2-0-not-support-1-8x-lua/4523/3 "2019-11-21T21:06:34Z")

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thanks for your reply and help.  
have a good day