remove requirement for setuptools.pkg_resources

Fixes pydata#5676

Now depends on importlib-metadata for Python major version < 3.8

setup.cfg

@@ -78,7 +78,7 @@ python_requires = >=3.7
 install_requires =
     numpy >= 1.17
     pandas >= 1.0
-    setuptools >= 40.4  # For pkg_resources
+    importlib-metadata; python_version < '3.8'
 
 [options.extras_require]
 io =

xarray/__init__.py

@@ -1,5 +1,3 @@
-import pkg_resources
-
 from . import testing, tutorial, ufuncs
 from .backends.api import (
     load_dataarray,
@@ -28,13 +26,25 @@
 from .core.parallel import map_blocks
 from .core.variable import Coordinate, IndexVariable, Variable, as_variable
 from .util.print_versions import show_versions
-
 try:
-    __version__ = pkg_resources.get_distribution("xarray").version
+    try:
+        from importlib.metadata import version, PackageNotFoundError
+    except ImportError:
+        try:
+            from importlib_metadata import version, PackageNotFoundError
+        except ImportError:
+            raise
+
+    try:
+        __version__ = version("xarray")
+    except PackageNotFoundError:
+        raise
+    del version, PackageNotFoundError
 except Exception:
     # Local copy or not installed with setuptools.
     # Disable minimum version checks on downstream libraries.
     __version__ = "999"
+    raise
 
 # A hardcoded __all__ variable is necessary to appease
 # `mypy --strict` running in projects that import xarray.

xarray/backends/plugins.py

@@ -95,8 +95,14 @@ def build_engines(pkg_entrypoints):
 
 @functools.lru_cache(maxsize=1)
 def list_engines():
-    pkg_entrypoints = pkg_resources.iter_entry_points("xarray.backends")
-    return build_engines(pkg_entrypoints)
+    try:
+        from importlib.metadata import Distribution
+    except ImportError:
+        from importlib_metadata import Distrubtion
+    importlib_entrypoints = (entry_point for entry_point
+                             in Distribution.from_name("xarray").entry_points
+                             if entry_point.module == "xarray.backends")
+    return build_engines(importlib_entrypoints)
 
 
 def guess_engine(store_spec):

xarray/core/formatting_html.py

@@ -3,8 +3,6 @@
 from functools import lru_cache, partial
 from html import escape
 
-import pkg_resources
-
 from .formatting import inline_variable_array_repr, short_data_repr
 from .options import _get_boolean_with_default
 
@@ -14,10 +12,14 @@
 @lru_cache(None)
 def _load_static_files():
     """Lazily load the resource files into memory the first time they are needed"""
-    return [
-        pkg_resources.resource_string("xarray", fname).decode("utf8")
-        for fname in STATIC_FILES
-    ]
+    import pathlib
+    parent = pathlib.Path(__file__).parent / "../"
+    result = []
+    for fname in STATIC_FILES:
+        with open(parent / fname) as fh:
+            result.append(fh.read().encode("utf8"))
+
+    return result
 
 
 def short_data_repr_html(array):