Dropshell Build

A Docker-based build system for creating statically-linked C++ executables using Alpine Linux and musl libc.

Overview

This repository provides a comprehensive C++ development environment with:

1. dropshell-build-base: A base image with C++ toolchain and libraries
2. dropshell-build: Multi-stage Docker build system for C++ projects
3. Test projects: Sample applications demonstrating the build system

Features

Libraries Available

The base image includes statically-linked versions of:

• Web Framework: Drogon with async HTTP capabilities
• Database Support: PostgreSQL (libpq), MySQL/MariaDB, SQLite3
• HTTP Clients:
  • Custom Drogon-based HTTP utilities (see ipdemo)
  • CPR (C++ Requests) library for simplified HTTP requests
• Networking: cURL, c-ares, OpenSSL
• JSON: nlohmann/json, jsoncpp
• Compression: zlib, zstd, lzma
• Logging: spdlog, fmt
• Utilities: ccache, mold linker

HTTP Client Options

Two HTTP client approaches are available:

1. Drogon HTTP Utilities (see tests/ipdemo/src/http_utils.hpp):

   auto response = http_get("example.com", "/api/endpoint", true, 10.0);
   if (response.success && response.status_code == 200) {
       std::cout << response.body << std::endl;
   }
   

2. CPR Library (C++ Requests):

   #include <cpr/cpr.h>
   cpr::Response r = cpr::Get(cpr::Url{"https://example.com/api"});
   if (r.status_code == 200) {
       std::cout << r.text << std::endl;
   }
   

   To use CPR in your CMakeLists.txt with proper static linking:

   find_package(nlohmann_json REQUIRED)
   
   # Find OpenSSL libraries (path varies by architecture)
   find_library(OPENSSL_SSL_LIB NAMES ssl PATHS /usr/local/lib64 /usr/local/lib NO_DEFAULT_PATH)
   find_library(OPENSSL_CRYPTO_LIB NAMES crypto PATHS /usr/local/lib64 /usr/local/lib NO_DEFAULT_PATH)
   
   # CPR static linking setup
   add_library(cpr::cpr_static STATIC IMPORTED)
   set_target_properties(cpr::cpr_static PROPERTIES
       IMPORTED_LOCATION "/usr/local/lib/libcpr.a"
       INTERFACE_INCLUDE_DIRECTORIES "/usr/local/include"
       INTERFACE_LINK_LIBRARIES "/usr/local/lib/libcurl.a;${OPENSSL_SSL_LIB};${OPENSSL_CRYPTO_LIB};/usr/lib/libz.a;/usr/lib/libzstd.a;lzma;dl"
   )
   
   target_link_libraries(${PROJECT_NAME} PRIVATE 
       nlohmann_json::nlohmann_json 
       cpr::cpr_static)
   

Quick Start

Building the Base Image

cd build-base
./build.sh

Building a Project

./build.sh

Testing

./test.sh

Project Structure

Test Projects

• ipdemo: Demonstrates Drogon HTTP utilities and JSON processing
• test_libs: Tests all available libraries (fmt, spdlog, SQLite3, etc.)
• cprdemo: Example using CPR library for HTTP requests

Environment Variables

• CMAKE_BUILD_TYPE: "Debug" or "Release" (default: Debug)
• PROJECT: Project name to build (default: ipdemo)

Installation