bz2 library cannot be found if package libbz2-dev is not installed

[rikka0w0]

Found on Debian 13 x86_64 + openresty/1.27.1.2

lua-resty-bzlib/lualib/resty/bzlib/init.lua

Line 28 in 4a9c802

local bzlib = ffi.load('bz2')

Change to

local bzlib = ffi.load('libbz2.so.1')

to solve the issue. Otherwise, users would have to manually sudo apt install libbz2-dev.