How do you install lua-resty-string in openresty docker image? - lua

Question

I want to use sha256 in my openresty code so tried installing lua-resty-string.
I am clearly missing some other package(s), but have no idea which ones. The lua-resty-string homepage offers no clue that I can see.
$ docker run --rm -it openresty/openresty bash
# apt-get update && apt-get install luarocks
# luarocks install lua-resty-string
Installing https://luarocks.org/lua-resty-string-0.09-0.rockspec
lua-resty-string 0.09-0 is now installed in /usr/local (license: )
root#28fe64c51c5a:/# luajit
LuaJIT 2.1.0-beta3 -- Copyright (C) 2005-2017 Mike Pall. http://luajit.org/
JIT: ON SSE2 SSE3 SSE4.1 fold cse dce fwd dse narrow loop abc sink fuse
> resty_sha256 = require "resty.sha256"
> sha256 = resty_sha256:new()
/usr/local/share/lua/5.1/resty/sha256.lua:41: luajit: undefined symbol: SHA256_Init
stack traceback:
[C]: in function '__index'
/usr/local/share/lua/5.1/resty/sha256.lua:41: in function 'new'
stdin:1: in main chunk
[C]: at 0x55cd1fdaf250
I would be more convinced that luarocks if it would build or install software correctly.
What I am missing (this time)?

Answer 1

It seems that the lua-resty-string package only works when code is executed by the nginx server.
root#62817b2fe1b2:/# ldd `which nginx`
linux-vdso.so.1 (0x00007ffe3b1db000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fa367a81000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fa367a60000)
libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007fa367a26000)
libluajit-5.1.so.2 => /usr/local/openresty/luajit/lib/libluajit-5.1.so.2 (0x00007fa3679a3000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fa367820000)
libpcre.so.1 => /usr/local/openresty/pcre/lib/libpcre.so.1 (0x00007fa3677ad000)
libssl.so.1.1 => /usr/local/openresty/openssl/lib/libssl.so.1.1 (0x00007fa367739000)
libcrypto.so.1.1 => /usr/local/openresty/openssl/lib/libcrypto.so.1.1 (0x00007fa3674ad000)
libz.so.1 => /usr/local/openresty/zlib/lib/libz.so.1 (0x00007fa367490000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fa3672cf000)
/lib64/ld-linux-x86-64.so.2 (0x00007fa367c97000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fa3672b5000)
root#62817b2fe1b2:/# nm -D /usr/local/openresty/openssl/lib/libcrypto.so.1.1 | grep SHA256_Init
00000000001b12a0 T SHA256_Init
And that library comes with openresty:
root#62817b2fe1b2:/# dpkg -S /usr/local/openresty/openssl/lib/libcrypto.so.1.1
openresty-openssl: /usr/local/openresty/openssl/lib/libcrypto.so.1.1
So the real question I suppose it how do you tell luajit to load that library so that it can resolve SHA256_Init when resty.sha256 is imported.
And that it seems can be done with ffi:
local ffi = require("ffi")
local crypto = ffi.load("/usr/local/openresty/openssl/lib/libcrypto.so.1.1", true)