Generate constructor artifacts

Fixes conda-incubator#657.

conda-store-server/conda_store_server/action/__init__.py

@@ -32,3 +32,6 @@
 from conda_store_server.action.add_lockfile_packages import (
     action_add_lockfile_packages,  # noqa
 )
+from conda_store_server.action.generate_constructor_artifacts import (
+    action_generate_constructor_artifacts,  # noqa
+)

conda-store-server/conda_store_server/action/generate_constructor_artifacts.py

@@ -0,0 +1,98 @@
+import pathlib
+import subprocess
+import sys
+import tempfile
+
+import yaml
+from conda_store_server import action, schema
+
+
+@action.action
+def action_generate_constructor_artifacts(
+    context,
+    conda_command: str,
+    specification: schema.CondaSpecification,
+    installer_dir: str,
+):
+    # Helpers
+    def print_cmd(cmd):
+        context.log.info(f"Running command: {' '.join(cmd)}")
+        context.log.info(
+            subprocess.check_output(cmd, stderr=subprocess.STDOUT, encoding="utf-8")
+        )
+
+    def write_file(filename, s):
+        with open(filename, "w") as f:
+            context.log.info(f"{filename}:\n{s}")
+            f.write(s)
+
+    # pip dependencies are not directly supported by constructor, they will be
+    # installed via the post_install script:
+    # https://github.com/conda/constructor/issues/515
+    dependencies = []
+    pip_dependencies = []
+    for d in specification.dependencies:
+        if type(d) is schema.CondaSpecificationPip:
+            pip_dependencies.extend(d.pip)
+        else:
+            dependencies.append(d)
+
+    # Creates the construct.yaml file and post_install script
+    ext = ".exe" if sys.platform == "win32" else ".sh"
+    installer_dir = pathlib.Path(installer_dir)
+    installer_filename = (installer_dir / specification.name).with_suffix(ext)
+
+    with tempfile.TemporaryDirectory() as tmp_dir:
+        tmp_dir = pathlib.Path(tmp_dir)
+        construct_file = tmp_dir / "construct.yaml"
+        post_install_file = tmp_dir / "post-install.sh"
+        env_dir = tmp_dir / "env"
+
+        construct = {
+            "installer_filename": str(installer_filename),
+            "post_install": str(post_install_file),
+            "name": specification.name,
+            "channels": specification.channels,
+            "specs": dependencies,
+            # XXX: This is required: use the env hash and datetime?
+            "version": 1,
+        }
+
+        # XXX: Support Windows
+        post_install = """\
+#!/usr/bin/env bash
+set -euxo pipefail
+"""
+        if pip_dependencies:
+            post_install += f"""
+conda run -p "$PREFIX" pip install {' '.join(pip_dependencies)}
+"""
+
+        # Writes files to disk
+        write_file(construct_file, yaml.dump(construct))
+        write_file(post_install_file, post_install)
+
+        # Installs constructor
+        command = [
+            conda_command,
+            "create",
+            "-y",
+            "-p",
+            str(env_dir),
+            "constructor",
+        ]
+        print_cmd(command)
+
+        # Calls constructor
+        command = [
+            conda_command,
+            "run",
+            "-p",
+            str(env_dir),
+            "--no-capture-output",
+            "constructor",
+            str(tmp_dir),
+        ]
+        print_cmd(command)
+
+    return installer_filename

conda-store-server/tests/test_actions.py

@@ -1,8 +1,11 @@
 import asyncio
 import datetime
+import os
 import pathlib
 import re
+import subprocess
 import sys
+import tempfile
 
 import pytest
 import yarl
@@ -110,6 +113,43 @@ def test_solve_lockfile_multiple_platforms(conda_store, specification, request):
     assert len(context.result["package"]) != 0
 
 
+@pytest.mark.parametrize(
+    "specification_name",
+    [
+        "simple_specification",
+        "simple_specification_with_pip",
+    ],
+)
+def test_generate_constructor_artifacts(conda_store, specification_name, request):
+    specification = request.getfixturevalue(specification_name)
+    with tempfile.TemporaryDirectory() as installer_dir:
+        # Creates the installer
+        context = action.action_generate_constructor_artifacts(
+            conda_command=conda_store.conda_command,
+            specification=specification,
+            installer_dir=installer_dir,
+        )
+
+        # Checks that the installer was created
+        installer = context.result
+        assert installer.exists()
+
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            # Runs the installer
+            out_dir = pathlib.Path(tmp_dir) / 'out'
+            subprocess.check_output([installer, '-b', '-p', str(out_dir)])
+
+            # Checks the output directory
+            assert out_dir.exists()
+            lib_dir = out_dir / 'lib'
+            if specification_name == 'simple_specification':
+                assert any(str(x).endswith('libz.so') for x in lib_dir.iterdir())
+            else:
+                # Uses rglob to not depend on the version of the python
+                # directory, which is where site-packages is located
+                assert any(str(x).endswith('site-packages/flask') for x in lib_dir.rglob('*'))
+
+
 def test_fetch_and_extract_conda_packages(tmp_path, simple_conda_lock):
     context = action.action_fetch_and_extract_conda_packages(
         conda_lock_spec=simple_conda_lock,