drop py36 support

.cirrus.yml

@@ -137,8 +137,6 @@ test_minimal_task:
   only_if: ${SKIP_TEST_MINIMAL_TASK} == "" && ${SKIP_ALL_TEST_TASKS} == ""
   << : *CREDITS_TEMPLATE
   matrix:
-    env:
-      PY_VER: 3.6
     env:
       PY_VER: 3.7
     env:
@@ -159,8 +157,6 @@ test_full_task:
   only_if: ${SKIP_TEST_FULL_TASK} == "" && ${SKIP_ALL_TEST_TASKS} == ""
   << : *CREDITS_TEMPLATE
   matrix:
-    env:
-      PY_VER: 3.6
     env:
       PY_VER: 3.7
     env:

.github/workflows/refresh-lockfiles.yml

@@ -69,7 +69,7 @@ jobs:
 
     strategy:
       matrix:
-        python: ['36', '37', '38']
+        python: ['37', '38']
 
     steps:
       - uses: actions/checkout@v2

docs/src/conf.py

@@ -19,9 +19,15 @@
 
 # ----------------------------------------------------------------------------
 
+import datetime
 import ntpath
 import os
+from pathlib import Path
+import re
 import sys
+import warnings
+
+import iris
 
 
 # function to write  useful output to stdout, prefixing the source.
@@ -53,9 +59,6 @@ def autolog(message):
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
 
-import datetime
-import warnings
-
 # custom sphinx extensions
 sys.path.append(os.path.abspath("sphinxext"))
 
@@ -80,8 +83,6 @@ def autolog(message):
 # |version| and |release|, also used in various other places throughout the
 # built documents.
 
-import iris
-
 # The short X.Y version.
 if iris.__version__ == "dev":
     version = "dev"
@@ -101,9 +102,34 @@ def autolog(message):
 
 build_python_version = ".".join([str(i) for i in sys.version_info[:3]])
 
+
+def _dotv(version):
+    result = version
+    match = re.match("^py(\d+)$", version)  # noqa: W605
+    if match:
+        digits = match.group(1)
+        if len(digits) > 1:
+            result = f"{digits[0]}.{digits[1:]}"
+    return result
+
+
+# Automate the discovery of the python versions tested with CI.
+python_support = [
+    fname.stem for fname in Path(".").glob("../../requirements/ci/py*.yml")
+]
+if not python_support:
+    python_support = "unknown Python versions"
+elif len(python_support) == 1:
+    python_support = f"Python {_dotv(python_support[0])}"
+else:
+    rest = ", ".join([_dotv(v) for v in python_support[:-1]])
+    last = _dotv(python_support[-1])
+    python_support = f"Python {rest} and {last}"
+
 rst_epilog = f"""
 .. |copyright_years| replace:: {copyright_years}
 .. |python_version| replace:: {build_python_version}
+.. |python_support| replace:: {python_support}
 .. |iris_version| replace:: v{version}
 .. |build_date| replace:: ({datetime.datetime.now().strftime('%d %b %Y')})
 """

docs/src/installing.rst

@@ -16,8 +16,7 @@ any WSL_ distributions.
 
 .. _WSL: https://docs.microsoft.com/en-us/windows/wsl/install-win10
 
-.. note:: Iris is currently supported and tested against Python ``3.6``,
-          ``3.7``, and ``3.8``.
+.. note:: Iris is currently supported and tested against |python_support|.
 
 .. note:: This documentation was built using Python |python_version|.
 

noxfile.py

@@ -20,7 +20,7 @@
 PACKAGE = str("lib" / Path("iris"))
 
 #: Cirrus-CI environment variable hook.
-PY_VER = os.environ.get("PY_VER", ["3.6", "3.7", "3.8"])
+PY_VER = os.environ.get("PY_VER", ["3.7", "3.8"])
 
 #: Default cartopy cache directory.
 CARTOPY_CACHE_DIR = os.environ.get("HOME") / Path(".local/share/cartopy")

setup.py

@@ -279,4 +279,5 @@ def long_description():
         "docs": pip_requirements("docs"),
         "test": pip_requirements("test"),
     },
+    python_requires=">=3.7",
 )