Modifying HAProxy Lua Library Path

Question

I am trying to load Lua script from HAProxy. In the Lua script, the following line is causing an error:

local http = require("socket.http")

Intially I gathered from journalctl -xe output that the library was not installed. I installed it using luarocks install luasocket. This did not solve the issue. The new error is module "socket.http" not found. Following the comment in this post I realized that I must change the settings for Lua library path in order to resolve this issue.

Now, I want to know the following:

1. Do I have install HAProxy+Lua from source and modify the library path pre installation?
2. If building from source is not necessary then, I believe I must change the path using syslog as suggested by the comment from post linked above. If this is the case, how do I do that and what settings do I need to change/add to syslog.conf?
3. Are there are any other solution that I am overlooking which, would easier than any of the above?

Thanks for your help in advance.

EDIT 1

I have modified both LUA_PATH and LUA_CPATH as follows:

LUA_PATH=/usr/bin/lua;/usr/bin/lua5.3;/usr/share/lua/5.3/ltn12.lua;/usr/share/lua/5.3/mime.lua;/usr/share/lua/5.3/socket.lua;/usr/share/lua/5.3/ssl.lua;/usr/share/lua/5.3/posix/_argcheck.lua;/usr/share/lua/5.3/posix/compat.lua;/usr/share/lua/5.3/posix/deprecated.lua;/usr/share/lua/5.3/posix/init.lua;/usr/share/lua/5.3/posix/sys.lua;/usr/share/lua/5.3/posix/util.lua;/usr/share/lua/5.3/posix/version.lua;/usr/share/lua/5.3/socket/ftp.lua;/usr/share/lua/5.3/socket/headers.lua;/usr/share/lua/5.3/socket/http.lua;/usr/share/lua/5.3/socket/smtp.lua;/usr/share/lua/5.3/socket/tp.lua;/usr/share/lua/5.3/socket/url.lua;/usr/share/lua/5.3/term/colors.lua;/usr/share/lua/5.3/term/cursor.lua;/usr/share/lua/5.3/term/init.lua;/usr/share/lua/5.3/ssl/https.lua;/usr/share/lua/5.3/luarocks/add.lua;/usr/share/lua/5.3/luarocks/admin_remove.lua;/usr/share/lua/5.3/luarocks/build.lua;/usr/share/lua/5.3/luarocks/cache.lua;/usr/share/lua/5.3/luarocks/cfg.lua;/usr/share/lua/5.3/luarocks/command_line.lua;/usr/share/lua/5.3/luarocks/config_cmd.lua;/usr/share/lua/5.3/luarocks/deps.lua;/usr/share/lua/5.3/luarocks/dir.lua;/usr/share/lua/5.3/luarocks/doc.lua;/usr/share/lua/5.3/luarocks/download.lua;/usr/share/lua/5.3/luarocks/fetch.lua;/usr/share/lua/5.3/luarocks/fs.lua;/usr/share/lua/5.3/luarocks/help.lua;/usr/share/lua/5.3/luarocks/index.lua;/usr/share/lua/5.3/luarocks/install.lua;/usr/share/lua/5.3/luarocks/lint.lua;/usr/share/lua/5.3/luarocks/list.lua;/usr/share/lua/5.3/luarocks/loader.lua;/usr/share/lua/5.3/luarocks/make.lua;/usr/share/lua/5.3/luarocks/make_manifest.lua;/usr/share/lua/5.3/luarocks/manif_core.lua;/usr/share/lua/5.3/luarocks/manif.lua;/usr/share/lua/5.3/luarocks/new_version.lua;/usr/share/lua/5.3/luarocks/pack.lua;/usr/share/lua/5.3/luarocks/path_cmd.lua;/usr/share/lua/5.3/luarocks/path.lua;/usr/share/lua/5.3/luarocks/persist.lua;/usr/share/lua/5.3/luarocks/purge.lua;/usr/share/lua/5.3/luarocks/refresh_cache.lua;/usr/share/lua/5.3/luarocks/remove.lua;/usr/share/lua/5.3/luarocks/repos.lua;/usr/share/lua/5.3/luarocks/require.lua;/usr/share/lua/5.3/luarocks/search.lua;/usr/share/lua/5.3/luarocks/show.lua;/usr/share/lua/5.3/luarocks/site_config.lua;/usr/share/lua/5.3/luarocks/type_check.lua;/usr/share/lua/5.3/luarocks/unpack.lua;/usr/share/lua/5.3/luarocks/upload.lua;/usr/share/lua/5.3/luarocks/util.lua;/usr/share/lua/5.3/luarocks/validate.lua;/usr/share/lua/5.3/luarocks/write_rockspec.lua;/usr/share/lua/5.3/luarocks/build/builtin.lua;/usr/share/lua/5.3/luarocks/build/cmake.lua;/usr/share/lua/5.3/luarocks/build/command.lua;/usr/share/lua/5.3/luarocks/build/make.lua;/usr/share/lua/5.3/luarocks/fs/lua.lua;/usr/share/lua/5.3/luarocks/fs/tools.lua;/usr/share/lua/5.3/luarocks/fs/unix.lua;/usr/share/lua/5.3/luarocks/fs/win32.lua;/usr/share/lua/5.3/luarocks/fetch/cvs.lua;/usr/share/lua/5.3/luarocks/fetch/git_file.lua;/usr/share/lua/5.3/luarocks/fetch/git_http.lua;/usr/share/lua/5.3/luarocks/fetch/git_https.lua;/usr/share/lua/5.3/luarocks/fetch/git.lua;/usr/share/lua/5.3/luarocks/fetch/git_ssh.lua;/usr/share/lua/5.3/luarocks/fetch/hg_http.lua;/usr/share/lua/5.3/luarocks/fetch/hg_https.lua;/usr/share/lua/5.3/luarocks/fetch/hg.lua;/usr/share/lua/5.3/luarocks/fetch/hg_ssh.lua;/usr/share/lua/5.3/luarocks/fetch/sscm.lua;/usr/share/lua/5.3/luarocks/fetch/svn.lua;/usr/share/lua/5.3/luarocks/tools/patch.lua;/usr/share/lua/5.3/luarocks/tools/tar.lua;/usr/share/lua/5.3/luarocks/tools/zip.lua;/usr/share/lua/5.3/luarocks/upload/api.lua;/usr/share/lua/5.3/luarocks/upload/multipart.lua

LUA_CPATH=/usr/lib64/lua/5.3/posix/ctype.so;/usr/lib64/lua/5.3/posix/dirent.so;/usr/lib64/lua/5.3/posix/errno.so;/usr/lib64/lua/5.3/posix/fcntl.so;/usr/lib64/lua/5.3/posix/fnmatch.so;/usr/lib64/lua/5.3/posix/glob.so;/usr/lib64/lua/5.3/posix/grp.so;/usr/lib64/lua/5.3/posix/libgen.so;/usr/lib64/lua/5.3/posix/poll.so;/usr/lib64/lua/5.3/posix/pwd.so;/usr/lib64/lua/5.3/posix/sched.so;/usr/lib64/lua/5.3/posix/signal.so;/usr/lib64/lua/5.3/posix/stdio.so;/usr/lib64/lua/5.3/posix/stdlib.so;/usr/lib64/lua/5.3/posix/syslog.so;/usr/lib64/lua/5.3/posix/termio.so;/usr/lib64/lua/5.3/posix/time.so;/usr/lib64/lua/5.3/posix/unistd.so;/usr/lib64/lua/5.3/posix/utime.so;/usr/lib64/lua/5.3/mime/core.so;/usr/lib64/lua/5.3/socket/core.so;/usr/lib64/lua/5.3/socket/serial.so;/usr/lib64/lua/5.3/socket/unix.so;/usr/lib64/lua/5.3/term/core.so;/usr/lib64/lua/5.3/ssl.so;/usr/lib64/lua/5.3/zlib.so

I am still getting the same error as reported before.

EDIT 2

Found this post on Lua require function quite helpful. Following the discussion, I tried the following:

package.path="/usr/share/lua/5.3/?/?.lua" package.cpath="/usr/lib64/lua/5.3/?/?.so"

I added these lines at the top my lua script that's causing the error. I also modified the environment variables, LUA_PATH and LUA_CPATH with the same value. The error still persists.

I am out of all possible options at this stage and would be glad if someone can shed some light on this issue.

Bradfield

Lua reads library path from optional env variables LUA_PATH and LUA_CPATH when VM is starting. – Dihydric

@EgorSkriptunoff All my Lua files are in /usr/lib64/lua/5.3/ which, contains all the socket files, *.so. and /usr/share/lua/5.3 which contains a set of scripts. I have modified /etc/bash.bashrc.local with export LUA_PATH=/usr/bin/lua. For LUA_CPATH do I need to individually add all socket file names? – Bradfield

@EgorSkriptunoff I added LUA_CPATH=/usr/lib64/lua/5.3 but the error still persists – Bradfield

LUA_PATH=;;/usr/lib64/lua/5.3/?.lua;/usr/lib64/lua/5.3/?/init.lua; – Dihydric

@EgorSkriptunoff Added /usr/share/lua/5.3/posix/init.lua. Not sure which other file you meant by /usr/lib64/lua/5.3/?.lua. – Bradfield

@EgorSkriptunoff Did not solve the issue after last modification to LUA_PATH – Bradfield

I know it is some time ago but how about export LUA_CPATH=;;/usr/lib64/lua/5.3/?.so for the C (*.so) files - ? is the symbol that gets replaced by the package name when the package loader goes looking for C (or indeed Lua) files but you need to append the relevant extension - which can vary on different OSes. 8-) – Landwaiter

Actually ? is the symbol that is normally used for the name of the package in the searching - but in fact it is the third value in the five held in package.config. The others are 1: directory separator usually / on most systems but can be \ (that is a SINGLE backslash character BTW) on windows, 2: path separator usually ; but could be something else in some OSes (e.g. :) and two more that I can't remember but https://mcmap.net/q/1175705/-what-do-the-last-lines-in-lua-39-s-package-config-mean/4805858 might make it clearer... – Landwaiter

@Landwaiter I have not worked with Lua since posting this project. I think the information you posted is right and I'll check them out next time I use HAProxy and need Lua scripting. My solution was to fallback to Nodejs for the relevant logic – Bradfield

Did you see you can use lua-prepend-path? cbonte.github.io/haproxy-dconv/2.2/… You would want instead lua-prepend-path /usr/share/lua/5.3/?.lua and lua-prepend-path /usr/lib64/lua/5.3/posix/?.so cpath – Bastian