CODEWITHSUNDEEP
luahaproxyluasocket
Jim W
Jim W

Reputation: 5016

Using Lua package (LuaSocket) with HAProxy

I have installed HAProxy with Lua 5.3.1, and also LuaSocket.

I have LUA_PATH and LUA_CPATH defined:

export LUA_PATH="/usr/local/share/lua/5.3/?.lua;?.lua"
export LUA_CPATH="/usr/local/lib/lua/5.3/?.so;?.so"

and I'm using LuaSocket in my .lua file

core.register_fetches("myfunc", function(txn)

    ...
    local http = require("socket.http")    
    r, e = http.request("http://localhost:5001/api/Registry/")

however I can see from journalctl -xe that it isn't working

Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]: [ALERT] 344/232733 (16734) : Lua sample-fetch 'myfunc': runtime error: /home/ubuntu/haproxy-mapping.lua:12: module 'socket.http' not found:
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no field package.preload['socket.http']
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file '/usr/local/share/lua/5.3/socket/http.lua'
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file '/usr/local/share/lua/5.3/socket/http/init.lua'
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file '/usr/local/lib/lua/5.3/socket/http.lua'
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file '/usr/local/lib/lua/5.3/socket/http/init.lua'
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file './socket/http.lua'
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file './socket/http/init.lua'
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file '/usr/local/lib/lua/5.3/socket/http.so'
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file '/usr/local/lib/lua/5.3/loadall.so'
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file './socket/http.so'
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file '/usr/local/lib/lua/5.3/socket.so'
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file '/usr/local/lib/lua/5.3/loadall.so'
Dec 11 23:27:33 ip-172-31-5-92 haproxy[16731]:         no file './socket.so' from [C] global 'require', /home/ubuntu/haproxy-mapping.lua:12 C function line 4.

I'm surprised that it cannot find /usr/local/share/lua/5.3/socket/http.lua because it's there:

me$ ls -l /usr/local/share/lua/5.3/socket
total 56
-rw-r--r-- 1 root root 10640 Dec 11 21:31 ftp.lua
-rw-r--r-- 1 root root  3698 Dec 11 21:31 headers.lua
-rw-r--r-- 1 root root 14588 Dec 11 21:31 http.lua
-rw-r--r-- 1 root root  8074 Dec 11 21:31 smtp.lua
-rw-r--r-- 1 root root  3766 Dec 11 21:31 tp.lua
-rw-r--r-- 1 root root 11675 Dec 11 21:31 url.lua

It is saying

  no file './socket.so' from [C] global 'require', /home/ubuntu/haproxy-mapping.lua:12 C function line 4.

is that the core of the issue? There is no socket.so on the machine

Update: forgot to mention that I can use LuaSocket from Lua directly, just not when it's embedded in HAProxy.

Update 2: I suspect permissions. I ran strace on it and found

open("/usr/local/share/lua/5.3/socket/http.lua", O_RDONLY) = -1 ENOENT (No such file or directory)

and I know that haproxy is running as the user haproxy

me   :/usr/local/share/lua/5.3/socket$ ps -o user= -p 3273
haproxy

and yet if I switch user to haproxy I can read the file

me   :/usr/local/share/lua/5.3/socket$ su - haproxy
Password:
No directory, logging in with HOME=/
$ more /usr/local/share/lua/5.3/socket/http.lua
...listing...

and I also changed owner of the http.lua file to haproxy and it still can't open the file.

Upvotes: 0

Views: 961

Answers (1)

Jim W
Jim W

Reputation: 5016

I can only assume this is something to do with the context that the Lua function runs with-in when it is called, because changing the code to

local http = require("socket.http")    
core.register_fetches("myfunc", function(txn)
    ...

worked.

UPDATE: according to this https://www.arpalert.org/src/haproxy-lua-api/1.7/index.html during initialization you can DNS lookups but in runtime mode you cannot. It doesn't say anything about files but it seems reasonable to believe you can't do files either.

Upvotes: 0

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