scuba: Use importlib.metadata over pkg_resources for getting version

pkg_resources is deprecated:
https://setuptools.pypa.io/en/latest/pkg_resources.html

This prefers importlib.metadata (introduced in Python 3.8) and uses the
backport importlib_metadata for Python 3.7 (to be removed in #242).

Fixes #245

CHANGELOG.md

@@ -2,6 +2,11 @@
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
+## [Unreleased]
+### Changed
+- Removed use of deprecated `pkg_resources` (#247)
+
+
 ## [2.12.0] - 2023-09-15
 ### Added
 - Enable the use of relative paths in a volume hostpath (#227)

VERSIONING.md

@@ -52,4 +52,5 @@ versioning scheme. Consider a base version of `1.2.3`:
    created via `python setup.py sdist`. In this case, the version comes from
    the egg info generated by setuptools.
 
-In any case, when Scuba is installed, the version comes from `pkg_resources`.
+In any case, when Scuba is installed, the version comes from
+`importlib.metadata`.

pyproject.toml

@@ -17,6 +17,8 @@ classifiers = [
 ]
 dependencies = [
     "PyYAML",
+    # TODO(#242): Remove when Python 3.7 support is removed.
+    "importlib_metadata; python_version<'3.8'",
 ]
 description = "Simplify use of Docker containers for building software"
 keywords = ["docker"]
@@ -42,6 +44,8 @@ changelog = "https://github.com/JonathonReinhart/scuba/blob/main/CHANGELOG.md"
 requires = [
     "wheel",
     "setuptools >= 42.0.0",
+    # TODO(#242): Remove when Python 3.7 support is removed.
+    "importlib_metadata; python_version<'3.8'",
 ]
 
 

requirements.txt

@@ -5,7 +5,6 @@ PyYAML
 pytest
 pytest-cov
 types-PyYAML
-types-pkg-resources
 coverage
 black~=23.0  # Must match .github/workflows/black.yml
 -r docs/requirements.txt

scuba/version.py

@@ -67,19 +67,17 @@ def get_version() -> str:
     if not git_archive_rev.startswith("$"):
         return f"{BASE_VERSION}+g{git_archive_rev}"
 
-    # Package resource
     # Otherwise, we're either installed (e.g. via pip), or running from
     # an 'sdist' source distribution, and have a local PKG_INFO file.
-    import pkg_resources
 
-    try:
-        return pkg_resources.get_distribution(DIST_SPEC).version
-    except pkg_resources.DistributionNotFound:
-        pass
+    # TODO(#242): Remove backport when Python 3.7 support is removed.
+    if sys.version_info >= (3, 8):
+        import importlib.metadata as importlib_metadata
+    else:
+        import importlib_metadata  # backport
 
-    # This shouldn't be able to happen
-    sys.stderr.write("WARNING: Failed to determine version!\n")
-    return BASE_VERSION
+    # Can raise importlib.metadata.PackageNotFoundError
+    return importlib_metadata.version(DIST_SPEC)
 
 
 __version__ = get_version()