Use launcher approach

Enables use of dlopen(3)

Author: qznc

.gitignore

@@ -4,3 +4,4 @@ test-python/
 output/
 package/
 work/
+build/

Makefile

@@ -4,19 +4,20 @@
 PYTHON_VERSION := 3.12.12
 
 .PHONY: default clean test
-default: python-$(PYTHON_VERSION)-static-x86_64-linux-musl.tar.gz
+
+default: python-$(PYTHON_VERSION)-x86_64-linux.tar.gz
 
 test: test.log
+	cat $<
 
-test.log: python-$(PYTHON_VERSION)-static-x86_64-linux-musl.tar.gz test.sh
-	./test.sh $< >$@ 2>&1
+test.log: python-$(PYTHON_VERSION)-x86_64-linux.tar.gz
+	./test.sh build/output >test.log 2>&1
 
-build/output/bin/python3.12: Containerfile.base build.sh
+build/output/bin/python3.12: Containerfile.base build.sh in_container/launcher.c in_container/build.sh
 	PYTHON_VERSION=$(PYTHON_VERSION) ./build.sh >build.log 2>&1
 
-python-$(PYTHON_VERSION)-static-x86_64-linux-musl.tar.gz: build/output/bin/python3.12 package.sh
+python-$(PYTHON_VERSION)-x86_64-linux.tar.gz: build/output/bin/python3.12 package.sh
 	PYTHON_VERSION=$(PYTHON_VERSION) ./package.sh >package.log 2>&1
 
 clean:
-	rm -rf test-python
-	rm -rf build *.tar.gz *.log
+	rm -rf build *.tar.gz *.log test-python

README.md

@@ -1,11 +1,12 @@
 # Portable Python
 
-Self-contained static Python distribution for Linux. Works on any distro without system dependencies. Statically linked from source with musl libc.
+Self-contained Python distribution for Linux. Works on any distro without system dependencies. Uses a launcher approach with full dynamic extension support.
 
 ## Features
 
 - Works on any x86_64 Linux distro (no system dependencies)
-- Statically linked binary with SSL, sqlite3, compression support
+- Full dynamic C extension support (NumPy, pandas, etc. work!)
+- Tiny launcher + shared libpython
 - Includes pip pre-installed and working
 - Space-efficient hardlinked environments
 - Independent site-packages per environment
@@ -16,8 +17,8 @@ Self-contained static Python distribution for Linux. Works on any distro without
 
 ```bash
 make  # build tarball from scratch
-tar -xzf python-3.12.12-static-x86_64-linux-musl.tar.gz  # extract tarball
-./python-static/bin/instantiate.py my-env  # create isolated environment
+tar -xzf python-3.12.12-x86_64-linux.tar.gz  # extract tarball
+./output/bin/instantiate.py my-env  # create isolated environment
 
 # Use the environment:
 ./my-env/bin/python3 --version
@@ -27,7 +28,8 @@ tar -xzf python-3.12.12-static-x86_64-linux-musl.tar.gz  # extract tarball
 
 ## How It Works
 
-Python is compiled from source with static linking in an Alpine Linux container. All dependencies (OpenSSL, sqlite3, zlib, bzip2, xz, readline, ncurses) are statically linked into the binary. The result is a truly portable single binary.
+Python is compiled from source in an Alpine Linux container.
+A small kinda-static launcher dynamically loads libpython at runtime, enabling full dynamic extension support while maintaining portability.
 
 `instantiate.py` creates environments using hardlinks (no copying) with independent site-packages. Multiple environments share base files on disk.
 
@@ -50,9 +52,9 @@ Python is compiled from source with static linking in an Alpine Linux container.
 Create multiple independent environments:
 
 ```bash
-./python-static/bin/instantiate.py dev-env
-./python-static/bin/instantiate.py prod-env
-./python-static/bin/instantiate.py test-env
+./output/bin/instantiate.py dev-env
+./output/bin/instantiate.py prod-env
+./output/bin/instantiate.py test-env
 
 # Each gets independent packages
 ./dev-env/bin/pip install pytest
@@ -62,19 +64,17 @@ Create multiple independent environments:
 
 ## Technical Details
 
-- Python 3.12.12 statically linked with musl libc
-- OpenSSL, sqlite3, zlib, bzip2, xz, readline, ncurses statically linked
+- Python 3.12.12 with launcher approach (kinda-static launcher + shared libpython)
+- OpenSSL, sqlite3, zlib, bzip2, xz, readline, ncurses support
+- Full dynamic C extension loading support
 - x86_64 Linux only
-- ~13MB tarball, ~39MB extracted
+- ~38MB tarball, ~100MB extracted
 
 ## Limitations
 
 - x86_64 Linux only (no ARM, macOS, Windows, BSD)
-- the fully static binary cannot load `.so` files at runtime: "Dynamic loading not supported"
-  - This is a fundamental limitation of fully static binaries with no dynamic linker because the library code cannot find symbols of the binary
 - musl libc may be incompatible with some glibc-specific packages
 - No Tkinter/GUI packages
-- ctypes has limited functionality (pythonapi not available in static build)
 
 ## License
 

build-inside-container.sh

@@ -10,7 +10,6 @@ WORK_DIR="$BUILD_DIR/work"
 CACHED_IMAGE="python-builder:alpine-3.22.1-deps"
 CONTAINERFILE="$SCRIPT_DIR/Containerfile.base"
 
-info() { echo "$1"; }
 error() { echo "ERROR: $1"; exit 1; }
 
 # Check for container runtime
@@ -22,10 +21,16 @@ else
     error "Neither podman nor docker found. Please install one."
 fi
 
-info "Building base image with dependencies..."
+echo "=========================================="
+echo "Building Portable Python"
+echo "  - Tiny static launcher (~14KB)"
+echo "  - Shared libpython with full dynamic extension support"
+echo "  - Portable + full functionality"
+
+echo "Building base image with dependencies..."
 $CONTAINER_CMD build -t "$CACHED_IMAGE" -f "$CONTAINERFILE" "$SCRIPT_DIR"
 
-info "Building Python $PYTHON_VERSION"
+echo "Building Python $PYTHON_VERSION..."
 mkdir -p "$OUTPUT_DIR"
 mkdir -p "$WORK_DIR"
 
@@ -36,18 +41,33 @@ $CONTAINER_CMD run --rm \
     --env LC_ALL=C.UTF-8 \
     --env SOURCE_DATE_EPOCH=1609459200 \
     --env PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin \
-    -v "$SCRIPT_DIR:/build:ro" \
+    -v "$SCRIPT_DIR/in_container:/in_container:ro" \
     -v "$OUTPUT_DIR:/output:rw" \
     -v "$WORK_DIR:/work:rw" \
     "$CACHED_IMAGE" \
-    /bin/sh /build/build-inside-container.sh $PYTHON_VERSION
+    /bin/sh /in_container/build.sh $PYTHON_VERSION
 
 PYTHON_BIN="$OUTPUT_DIR/bin/python${PYTHON_MAJOR_MINOR}"
-if [ -f "$PYTHON_BIN" ]; then
-    CHECKSUM=$(sha256sum "$PYTHON_BIN" | cut -d' ' -f1)
-    info "Binary: $PYTHON_BIN"
-    info "Size: $(ls -lh "$PYTHON_BIN" | awk '{print $5}')"
-    info "SHA256: $CHECKSUM"
-else
-    error "Build failed - output binary not found"
+LIBPYTHON="$OUTPUT_DIR/lib/libpython${PYTHON_MAJOR_MINOR}.so.1.0"
+
+if [ ! -f "$PYTHON_BIN" ]; then
+    error "Build failed - launcher binary not found"
 fi
+
+if [ ! -f "$LIBPYTHON" ]; then
+    error "Build failed - libpython not found"
+fi
+
+
+echo "=========================================="
+echo "Build Summary"
+echo "Launcher: $PYTHON_BIN"
+echo "  Size: $(ls -lh "$PYTHON_BIN" | awk '{print $5}')"
+echo "  SHA256: $(sha256sum "$PYTHON_BIN" | cut -d' ' -f1)"
+echo ""
+echo "libpython: $LIBPYTHON"
+echo "  Size: $(ls -lh "$LIBPYTHON" | awk '{print $5}')"
+echo "  SHA256: $(sha256sum "$LIBPYTHON" | cut -d' ' -f1)"
+echo ""
+echo "Output directory: $OUTPUT_DIR"
+echo "=========================================="

build.sh

@@ -0,0 +1,10 @@
+This directory contains everything that's needed **inside the container** during the build process.
+
+The host system's `build.sh` script:
+
+1. Builds the Alpine container image
+2. Mounts this directory as `/in_container` (read-only)
+3. Mounts output directories for build artifacts
+4. Runs `/in_container/build.sh` inside the container
+
+This separation keeps the container environment isolated and makes it clear which files are used where.