Support pixi as environment manager (drivendataorg#459)

* intial pixi commit

* linting

* update ci pixi settings

Author: pjbull

.github/workflows/tests.yml

@@ -75,6 +75,12 @@ jobs:
           auto-activate-base: true
           activate-environment: ""
 
+      - name: Set up Pixi
+        uses: prefix-dev/setup-pixi@v0.8.12
+        with:
+          cache: false
+          run-install: false
+  
       - name: Cache conda packages
         uses: actions/cache@v4
         env:
@@ -117,6 +123,8 @@ jobs:
           pipenv --version
           which virtualenv
           virtualenv --version
+          which pixi
+          pixi --version
           which python
           python --version
           python -c "import platform; print(f'Python architecture: {platform.architecture()}')"

.gitignore

@@ -126,6 +126,11 @@ ipython_config.py
 #   https://pdm.fming.dev/#use-with-ide
 .pdm.toml
 
+# pixi
+#   pixi.lock should be committed to version control for reproducibility
+#   .pixi/ contains the environments and should not be committed
+.pixi/
+
 # PEP 582; used by e.g. github.com/David-OConnor/pyflow and github.com/pdm-project/pdm
 __pypackages__/
 

Makefile

@@ -22,7 +22,7 @@ create_environment:
 
 ## Install Python Dependencies
 requirements:
-	$(PYTHON_INTERPRETER) -m pip install -r dev-requirements.txt
+	$(PYTHON_INTERPRETER) -m pip install -U -r dev-requirements.txt
 
 ## Format the code using isort and black
 format:

ccds-help.json

@@ -147,6 +147,13 @@
                     "more_information": "[Docs](https://docs.astral.sh/uv/)"
                 } 
             },
+            {
+                "choice": "pixi",
+                "help": {
+                    "description": "A fast package manager built on top of the conda ecosystem with lock files for reproducible environments. Supports both pixi.toml and pyproject.toml. Requires pixi to be installed as a system binary (see docs for installation instructions).",
+                    "more_information": "[Docs](https://pixi.sh/)"
+                } 
+            },
             {
                 "choice": "none",
                 "help": {
@@ -173,7 +180,7 @@
             {
                 "choice": "pyproject.toml",
                 "help": {
-                    "description": "Modern configuration file for Python projects.",
+                    "description": "Modern configuration file for Python projects. Also supported by pixi when using tool.pixi sections.",
                     "more_information": "[Docs](https://packaging.python.org/en/latest/guides/writing-pyproject-toml/)"
                 }
             },
@@ -190,6 +197,13 @@
                     "description": "Format used by Pipenv",
                     "more_information": "[Docs](https://pipenv.pypa.io/en/latest/pipfile.html)"
                 } 
+            },
+            {
+                "choice": "pixi.toml",
+                "help": {
+                    "description": "Configuration file used by pixi for managing dependencies and environments.",
+                    "more_information": "[Docs](https://pixi.sh/latest/reference/pixi_manifest/)"
+                } 
             }
         ]
     },

ccds.json

@@ -16,13 +16,15 @@
         "conda",
         "pipenv",
         "uv",
+        "pixi",
         "none"
     ],
     "dependency_file": [
         "requirements.txt",
         "pyproject.toml",
         "environment.yml",
-        "Pipfile"
+        "Pipfile",
+        "pixi.toml"
     ],
     "pydata_packages": [
         "none",

ccds/hook_utils/dependencies.py

@@ -73,8 +73,60 @@ def write_python_version(python_version):
         f.write(tomlkit.dumps(doc))
 
 
+def _generate_pixi_dependencies_config(
+    packages, pip_only_packages, repo_name, module_name, python_version, description
+):
+    """Generate pixi dependencies configuration data.
+
+    Returns:
+        tuple: (conda_dependencies, pypi_dependencies, project_config)
+    """
+    # Project configuration
+    project_config = {
+        "name": repo_name,
+        "description": description
+        or "A data science project created with cookiecutter-data-science",
+        "version": "0.1.0",
+        "channels": ["conda-forge"],
+        "platforms": ["linux-64", "osx-64", "osx-arm64", "win-64"],
+    }
+
+    # Conda dependencies
+    conda_dependencies = {"python": f"~={python_version}.0"}
+
+    # Filter out pip and pip-only packages from conda dependencies
+    conda_packages = [
+        p for p in sorted(packages) if p not in pip_only_packages and p != "pip"
+    ]
+    for p in conda_packages:
+        conda_dependencies[p] = "*"
+
+    # PyPI dependencies
+    has_pip_packages = any(p in pip_only_packages for p in packages)
+    pypi_dependencies = {}
+
+    if has_pip_packages:
+        # Add pip to conda dependencies when we have PyPI packages
+        conda_dependencies["pip"] = "*"
+        for p in sorted(packages):
+            if p in pip_only_packages:
+                pypi_dependencies[p] = "*"
+
+    # Always add the module as editable PyPI dependency
+    pypi_dependencies[module_name] = {"path": ".", "editable": True}
+
+    return conda_dependencies, pypi_dependencies, project_config
+
+
 def write_dependencies(
-    dependencies, packages, pip_only_packages, repo_name, module_name, python_version
+    dependencies,
+    packages,
+    pip_only_packages,
+    repo_name,
+    module_name,
+    python_version,
+    environment_manager=None,
+    description=None,
 ):
     if dependencies == "requirements.txt":
         with open(dependencies, "w") as f:
@@ -88,8 +140,43 @@ def write_dependencies(
     elif dependencies == "pyproject.toml":
         with open(dependencies, "r") as f:
             doc = tomlkit.parse(f.read())
-        doc["project"].add("dependencies", sorted(packages))
-        doc["project"]["dependencies"].multiline(True)
+
+        # If using pixi, add pixi-specific configuration
+        if environment_manager == "pixi":
+            # Add pixi project configuration
+            if "tool" not in doc:
+                doc["tool"] = tomlkit.table()
+            if "pixi" not in doc["tool"]:
+                doc["tool"]["pixi"] = tomlkit.table()
+
+            # Generate pixi configuration using helper function
+            conda_deps, pypi_deps, project_config = _generate_pixi_dependencies_config(
+                packages,
+                pip_only_packages,
+                repo_name,
+                module_name,
+                python_version,
+                description,
+            )
+
+            # Add project configuration
+            doc["tool"]["pixi"]["project"] = tomlkit.table()
+            for key, value in project_config.items():
+                doc["tool"]["pixi"]["project"][key] = value
+
+            # Add conda dependencies
+            doc["tool"]["pixi"]["dependencies"] = tomlkit.table()
+            for dep, version in conda_deps.items():
+                doc["tool"]["pixi"]["dependencies"][dep] = version
+
+            # Add PyPI dependencies
+            doc["tool"]["pixi"]["pypi-dependencies"] = tomlkit.table()
+            for dep, version in pypi_deps.items():
+                doc["tool"]["pixi"]["pypi-dependencies"][dep] = version
+        else:
+            # Standard pyproject.toml dependencies
+            doc["project"].add("dependencies", sorted(packages))
+            doc["project"]["dependencies"].multiline(True)
 
         with open(dependencies, "w") as f:
             f.write(tomlkit.dumps(doc))
@@ -122,3 +209,47 @@ def write_dependencies(
             lines += ["", "[requires]", f'python_version = "{python_version}"']
 
             f.write("\n".join(lines))
+
+    elif dependencies == "pixi.toml":
+        # Generate pixi configuration using helper function
+        conda_deps, pypi_deps, project_config = _generate_pixi_dependencies_config(
+            packages,
+            pip_only_packages,
+            repo_name,
+            module_name,
+            python_version,
+            description,
+        )
+
+        with open(dependencies, "w") as f:
+            lines = ["[project]"]
+
+            # Add project configuration
+            for key, value in project_config.items():
+                if isinstance(value, str):
+                    lines.append(f'{key} = "{value}"')
+                elif isinstance(value, list):
+                    lines.append(f"{key} = {value}")
+                else:
+                    lines.append(f'{key} = "{value}"')
+
+            lines.append("")
+            lines.append("[dependencies]")
+
+            # Add conda dependencies
+            for dep, version in conda_deps.items():
+                lines.append(f'{dep} = "{version}"')
+
+            # Add PyPI dependencies if any
+            if pypi_deps:
+                lines.append("")
+                lines.append("[pypi-dependencies]")
+                for dep, config in pypi_deps.items():
+                    if isinstance(config, dict):
+                        # Handle editable local package
+                        lines.append(f'{dep} = {{ path = ".", editable = true }}')
+                    else:
+                        lines.append(f'{dep} = "{config}"')
+
+            f.write("\n".join(lines))
+            f.write("\n")

hooks/post_gen_project.py

@@ -92,6 +92,8 @@
     repo_name="{{ cookiecutter.repo_name }}",
     module_name="{{ cookiecutter.module_name }}",
     python_version="{{ cookiecutter.python_version_number }}",
+    environment_manager="{{ cookiecutter.environment_manager }}",
+    description="{{ cookiecutter.description }}",
 )
 
 write_python_version("{{ cookiecutter.python_version_number }}")

tests/conftest.py

@@ -52,6 +52,16 @@ def _is_valid(config):
             config["environment_manager"] != "conda"
         ):
             return False
+        # pixi is the only valid env manager for pixi.toml
+        if (config["dependency_file"] == "pixi.toml") and (
+            config["environment_manager"] != "pixi"
+        ):
+            return False
+        # pixi supports both pixi.toml and pyproject.toml
+        if (config["environment_manager"] == "pixi") and (
+            config["dependency_file"] not in ["pixi.toml", "pyproject.toml"]
+        ):
+            return False
         return True
 
     # remove invalid configs

tests/pixi_harness.sh

@@ -0,0 +1,63 @@
+#!/bin/bash
+set -ex
+
+PROJECT_NAME=$(basename $1)
+CCDS_ROOT=$(dirname $0)
+MODULE_NAME=$2
+
+# Check if pixi is installed
+if ! command -v pixi &> /dev/null; then
+    echo "pixi is not installed. Please install pixi first:"
+    echo "  macOS/Linux: curl -fsSL https://pixi.sh/install.sh | sh"
+    echo "  Windows: powershell -ExecutionPolicy ByPass -c \"irm -useb https://pixi.sh/install.ps1 | iex\""
+    exit 1
+fi
+
+# Configure exit / teardown behavior
+function finish {
+    # Cleanup pixi environment
+    if [ -d ".pixi" ]; then
+        rm -rf .pixi
+    fi
+    if [ -f "pixi.lock" ]; then
+        rm -f pixi.lock
+    fi
+}
+trap finish EXIT
+
+# Source the steps in the test
+source $CCDS_ROOT/test_functions.sh
+
+# Navigate to the generated project and run make commands
+cd $1
+
+make
+make create_environment
+make requirements
+
+# Run pixi-specific tests with simpler commands
+pixi run python --version
+echo "Testing basic import..."
+pixi run python -c "import $MODULE_NAME"
+
+# Test config importable if scaffolded  
+if [ -f "$MODULE_NAME/config.py" ]; then
+    echo "Testing config import..."
+    pixi run python -c "from $MODULE_NAME import config"
+fi
+
+# Run linting and formatting through pixi
+pixi run make lint
+pixi run make format
+
+# Custom pixi test function to avoid issues with test_functions.sh
+# Check that python is available in pixi environment
+echo "Testing pixi python availability..."
+if pixi run python -c "import sys" > /dev/null 2>&1; then
+    echo "Python is available in pixi environment"
+else
+    echo "ERROR: Python not available in pixi environment" 
+    exit 1
+fi
+
+echo "All done!"

tests/test_creation.py

@@ -171,6 +171,8 @@ def verify_makefile_commands(root, config):
         harness_path = test_path / "pipenv_harness.sh"
     elif config["environment_manager"] == "uv":
         harness_path = test_path / "uv_harness.sh"
+    elif config["environment_manager"] == "pixi":
+        harness_path = test_path / "pixi_harness.sh"
     elif config["environment_manager"] == "none":
         return True
     else: