main: add compability checks

Signed-off-by: Filipe Laíns <[email protected]>

.pre-commit-config.yaml

@@ -19,7 +19,7 @@ repos:
         exclude: docs/.*|tests/.*|noxfile.py
       - id: mypy
         name: mypy (Python 2)
-        additional_dependencies: ["pathlib2"]
+        additional_dependencies: ["pathlib2", "build", "packaging<21.0"]
         exclude: docs/.*|tests/.*|tools/.*|noxfile.py
         args: ["-2"]
 

pyproject.toml

@@ -13,6 +13,8 @@ requires-python = ">=2.7,!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*"
 requires = [
   "configparser >= 3.5; python_version < '3'",
   "importlib-resources; python_version < '3.7'",
+  "build >= 0.2.0",  # not a hard runtime requirement -- we can softfail
+  "packaging",  # not a hard runtime requirement -- we can softfail
 ]
 
 [tool.flit.scripts]

src/installer/__main__.py

@@ -5,9 +5,11 @@
 import distutils.dist
 import os
 import os.path
+import platform
 import py_compile
 import sys
 import sysconfig
+import warnings
 
 import installer
 import installer.destinations
@@ -16,6 +18,7 @@
 from installer._compat.typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
+    from email.message import Message
     from typing import Any, Dict, List, Optional, Sequence, Union
 
     from installer._compat.typing import Text
@@ -51,6 +54,12 @@ def main_parser():  # type: () -> argparse.ArgumentParser
             action="store_true",
             help="enable optimization",
         )
+    parser.add_argument(
+        "--skip-dependency-check",
+        "-s",
+        action="store_true",
+        help="don't check if the wheel dependencies are met",
+    )
     return parser
 
 
@@ -102,6 +111,47 @@ def generate_bytecode(record_dict, scheme_dict, levels, stripdir=None):
         _compile_records(record_dict, scheme_dict, compile_args)
 
 
+def check_python_version(metadata):  # type: (Message) -> None
+    """Check if the project support the current interpreter."""
+    try:
+        import packaging.specifiers
+    except ImportError:
+        warnings.warn(
+            "'packaging' module not available, "
+            "skiping python version compatibility check"
+        )
+
+    requirement = metadata["Requires-Python"]
+    if not requirement:
+        return
+
+    versions = requirement.split(",")
+    for version in versions:
+        specifier = packaging.specifiers.Specifier(version)
+        if platform.python_version() not in specifier:
+            raise RuntimeError(
+                "Incompatible python version, needed: {}".format(version)
+            )
+
+
+def check_dependencies(metadata):  # type: (Message) -> None
+    """Check if the project dependencies are met."""
+    try:
+        import build
+    except ImportError:
+        warnings.warn("'build' module not available, skiping dependency check")
+
+    missing = {
+        unmet
+        for requirement in metadata.get_all("Requires-Dist") or []
+        for unmet_list in build.check_dependency(requirement)
+        for unmet in unmet_list
+    }
+    if missing:
+        missing_list = ", ".join(missing)
+        raise RuntimeError("Missing requirements: {}".format(missing_list))
+
+
 def main(cli_args, program=None):
     # type: (Sequence[str], Optional[str]) -> None
     """Process arguments and perform the install."""
@@ -113,6 +163,13 @@ def main(cli_args, program=None):
     bytecode_stripdir = None  # type: Optional[str]
 
     with installer.sources.WheelFile.open(args.wheel) as source:
+        # compability checks
+        metadata_contents = source.read_dist_info("METADATA")
+        metadata = installer.utils.parse_metadata_file(metadata_contents)
+        check_python_version(metadata)
+        if not args.skip_dependency_check:
+            check_dependencies(metadata)
+
         scheme_dict = get_scheme_dict(source.distribution)
 
         # prepend DESTDIR to scheme paths