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How to Install Lapis on Termux

·3 mins

Lapis is a powerful framework for building web applications in Lua or MoonScript, specifically designed to run on top of OpenResty. In this post, I’ll show you how to install it on Termux, including how to overcome a common compilation error with the luaossl dependency and how to properly configure your environment for OpenResty.

Prerequisites #

Before we begin, ensure you have OpenResty installed. If you haven’t yet, check out my post on How to Install OpenResty on Termux (Natively).

Since OpenResty uses LuaJIT (which is compatible with Lua 5.1), we need to install our dependencies for the 5.1 version.

You’ll also need luarocks and a build environment:

pkg install lua51 luarocks build-essential openssl

The Challenge: Compiling luaossl #

When trying to install Lapis via LuaRocks on Termux, you might encounter a build error while compiling luaossl. The error typically looks like this:

src/openssl.c:1015:6: error: incompatible pointer to integer conversion initializing 'int' with an expression of type 'char * _Nonnull' [-Wint-conversion]
 1015 |         int rv = strerror_r(error, dst, lim);

This happens because the Android (Bionic) C library provides a GNU-style strerror_r (which returns a char *) instead of the XSI-compliant version (which returns an int) when _GNU_SOURCE is defined.

The Solution: Patching luaossl #

To fix this, we need to download the luaossl source, patch it, and install it manually for Lua 5.1.

1. Download and Unpack #

luarocks --lua-version=5.1 download luaossl
luarocks --lua-version=5.1 unpack luaossl-*.src.rock
cd luaossl-20250929-0/luaossl-rel-20250929

2. Patch the Source #

We need to modify src/openssl.c to correctly handle the strerror_r return type on Android. Open src/openssl.c, find the aux_strerror_r function (around line 1015), and update the #elif condition to include defined(__ANDROID__):

// Change this:
#elif STRERROR_R_CHAR_P
// To this:
#elif STRERROR_R_CHAR_P || defined(__ANDROID__)

3. Build and Install #

Now, run luarocks make ensuring you specify the Lua version:

luarocks --lua-version=5.1 make

Installing Lapis and Dependencies #

With luaossl successfully installed, you can now install Lapis and its other required dependencies for Lua 5.1:

luarocks --lua-version=5.1 install luasocket
luarocks --lua-version=5.1 install pgmoon
luarocks --lua-version=5.1 install lapis

Configuration for OpenResty #

To run Lapis on OpenResty in Termux, you need two more critical steps.

1. Update nginx.conf #

You must tell OpenResty where to find the Lua modules you installed via LuaRocks. Add these lines to the http block of your nginx.conf:

http {
    # ... other config ...
    lua_package_path "/data/data/com.termux/files/home/.luarocks/share/lua/5.1/?.lua;/data/data/com.termux/files/home/.luarocks/share/lua/5.1/?/init.lua;;";
    lua_package_cpath "/data/data/com.termux/files/home/.luarocks/lib/lua/5.1/?.so;;";
    # ...
}

2. Making it Permanent #

To avoid needing a script and allow running lapis server (or any LuaJIT-based tool) directly from any terminal session, add the LD_PRELOAD export to your ~/.bashrc:

echo 'export LD_PRELOAD=/data/data/com.termux/files/home/openresty-install/usr/local/openresty/luajit/lib/libluajit-5.1.so.2' >> ~/.bashrc
source ~/.bashrc

Verifying the Installation #

Start your server using the script:

chmod +x start_server.sh
./start_server.sh

You can verify that everything is working by visiting http://localhost:8080.

Happy coding with Lapis on Termux!