improve Python environment activation (#118)

Author: joshuadavidthomas

CHANGELOG.md

@@ -27,7 +27,7 @@ and this project attempts to adhere to [Semantic Versioning](https://semver.org/
 ### Changed
 
 - **Internal**: Moved task queueing functionality to `djls-server` crate, renamed from `Worker` to `Queue`, and simplified API.
-- Improved Python environment detection.
+- **Internal**: Improved Python environment handling, including refactored activation logic.
 
 ## [5.2.0a0]
 

Cargo.toml

@@ -13,8 +13,10 @@ anyhow = "1.0"
 async-trait = "0.1"
 pyo3 = "0.24"
 pyo3-async-runtimes = "0.24"
+pyo3-build-config = "0.24"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
+tempfile = "3.19"
 thiserror = "2.0"
 tokio = { version = "1.42", features = ["full"] }
 tower-lsp-server = { version = "0.21", features = ["proposed"] }

crates/djls-project/Cargo.toml

@@ -4,10 +4,13 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
-pyo3 = { workspace = true }
+pyo3 = { workspace = true, features = ["auto-initialize"] }
 tower-lsp-server = { workspace = true, features = ["proposed"] }
 
 which = "7.0.1"
 
+[build-dependencies]
+pyo3-build-config = { workspace = true, features = ["resolve-config"] }
+
 [dev-dependencies]
-tempfile = "3.19"
+tempfile = { workspace = true }

crates/djls-project/build.rs

@@ -0,0 +1,45 @@
+/// Build script to configure linking against the Python library.
+///
+/// This script is necessary when the crate's code, particularly tests
+/// that interact with the Python interpreter via `pyo3` (e.g., using
+/// `Python::with_gil`, importing modules, calling Python functions),
+/// needs symbols from the Python C API at link time.
+///
+/// It uses `pyo3-build-config` to detect the Python installation and
+/// prints the required `cargo:rustc-link-search` and `cargo:rustc-link-lib`
+/// directives to Cargo, enabling the linker to find and link against the
+/// appropriate Python library (e.g., libpythonX.Y.so).
+///
+/// It also adds an RPATH linker argument on Unix-like systems so the
+/// resulting test executable can find the Python library at runtime.
+///
+/// Note: Each crate whose test target requires Python linking needs its
+/// own `build.rs` with this logic.
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+
+    // Set up #[cfg] flags first (useful for conditional compilation)
+    pyo3_build_config::use_pyo3_cfgs();
+
+    // Get the Python interpreter configuration directly
+    let config = pyo3_build_config::get();
+
+    // Add the library search path if available
+    if let Some(lib_dir) = &config.lib_dir {
+        println!("cargo:rustc-link-search=native={}", lib_dir);
+
+        // Add RPATH linker argument for Unix-like systems (Linux, macOS)
+        // This helps the test executable find the Python library at runtime.
+        #[cfg(not(windows))]
+        println!("cargo:rustc-link-arg=-Wl,-rpath,{}", lib_dir);
+    } else {
+        println!("cargo:warning=Python library directory not found in config.");
+    }
+
+    // Add the library link directive if available
+    if let Some(lib_name) = &config.lib_name {
+        println!("cargo:rustc-link-lib=dylib={}", lib_name);
+    } else {
+        println!("cargo:warning=Python library name not found in config.");
+    }
+}