feat: Add back support for Python 3.9.

Author: commiterate

.github/workflows/.source.yml

@@ -13,6 +13,7 @@ jobs:
     strategy:
       matrix:
         python-binary:
+          - python3.9
           - python3.10
           - python3.11
           - python3.12

.gitlab/pipelines/.beta.yml

@@ -57,6 +57,7 @@ Run E2E Tests:
   parallel:
     matrix:
       - PYTHON_BINARY:
+          - python3.9
           - python3.10
           - python3.11
           - python3.12

.gitlab/pipelines/.production.yml

@@ -57,6 +57,7 @@ Create Package:
   parallel:
     matrix:
       - PYTHON_BINARY:
+          - python3.9
           - python3.10
           - python3.11
           - python3.12
@@ -78,22 +79,22 @@ Publish Package:
       artifacts: true
   parallel:
     matrix:
-      - PYTHON_TAG: ["cp310", "cp311", "cp312", "cp313"]
+      - PYTHON_TAG: ["cp39", "cp310", "cp311", "cp312", "cp313"]
         WHEEL_ARCH: arm64
         WHEEL_OS: macosx
         ARTIFACTORY_ARCH: arm64
         ARTIFACTORY_OS: macosx
-      - PYTHON_TAG: ["cp310", "cp311", "cp312", "cp313"]
+      - PYTHON_TAG: ["cp39", "cp310", "cp311", "cp312", "cp313"]
         WHEEL_ARCH: x86_64
         WHEEL_OS: macosx
         ARTIFACTORY_ARCH: x86_64
         ARTIFACTORY_OS: macosx
-      - PYTHON_TAG: ["cp310", "cp311", "cp312", "cp313"]
+      - PYTHON_TAG: ["cp39", "cp310", "cp311", "cp312", "cp313"]
         WHEEL_ARCH: aarch64
         WHEEL_OS: manylinux
         ARTIFACTORY_ARCH: aarch64
         ARTIFACTORY_OS: linux
-      - PYTHON_TAG: ["cp310", "cp311", "cp312", "cp313"]
+      - PYTHON_TAG: ["cp39", "cp310", "cp311", "cp312", "cp313"]
         WHEEL_ARCH: x86_64
         WHEEL_OS: manylinux
         ARTIFACTORY_ARCH: x86_64

.gitlab/pipelines/.source.yml

@@ -60,6 +60,7 @@ Build:
   parallel:
     matrix:
       - PYTHON_BINARY:
+          - python3.9
           - python3.10
           - python3.11
           - python3.12

.release_notes/.unreleased.md

@@ -1,3 +1,5 @@
 <!-- To avoid merge conflicts, add items at an arbitrary place in the list. -->
+
 - Add `msc config validate` command.
 - Added partial file caching with configurable chunk sizes, prefetch control, and source version validation for improved performance on large files.
+- Add back support for Python 3.9 (end of life starting October 2025).

flake.lock

@@ -16,6 +16,17 @@
       repo = "nixpkgs";
       ref = "refs/heads/nixos-unstable";
     };
+
+    # Python 3.9 (EOL October 2025) was dropped early for NixOS 25.05.
+    #
+    # https://github.com/NixOS/nixpkgs/pull/397258
+    nixpkgs-python39 = {
+      type = "github";
+      owner = "NixOS";
+      repo = "nixpkgs";
+      # Commit right before drop.
+      rev = "1076d576f5e8916f240d094a3c381d3e121800ba";
+    };
   };
 
   outputs =
@@ -45,7 +56,8 @@
         let
           # Attribute set of development shell name to Python package.
           devShellPythonPackages = with inputs.nixpkgs.legacyPackages.${system}; {
-            default = python310;
+            default = inputs.nixpkgs-python39.legacyPackages.${system}.python39;
+            "python3.9" = inputs.nixpkgs-python39.legacyPackages.${system}.python39;
             "python3.10" = python310;
             "python3.11" = python311;
             "python3.12" = python312;

flake.nix

@@ -13,13 +13,14 @@ authors = [
 ]
 license = "Apache-2.0"
 readme = "README.md"
-requires-python = ">=3.10,<4"
+requires-python = ">=3.9,<4"
 classifiers = [
     "License :: OSI Approved :: Apache Software License",
     "Programming Language :: Rust",
     "Programming Language :: Python :: Implementation :: CPython",
     "Programming Language :: Python :: Implementation :: PyPy",
     "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
@@ -84,7 +85,11 @@ hydra-core = [
     "hydra-core>=1,<2"
 ]
 numpy = [
-    "numpy>=2.1,<3"
+    "numpy>=2,<2.1; python_version == '3.9'",
+    "numpy>=2.1,<3; python_version >= '3.10'"
+]
+ray = [
+    "ray>=2.48,<3"
 ]
 torch = [
     "torch>=2.8,<3"
@@ -93,10 +98,9 @@ xarray = [
     "xarray>=2024.07.0"
 ]
 zarr = [
-    "zarr>=2.18.3,<3"
-]
-ray = [
-    "ray>=2.48,<3"
+    "zarr>=2.18.2,<3; python_version == '3.9'",
+    "zarr>=2.18.3,<3; python_version == '3.10'",
+    "zarr>=2.18.7,<3; python_version >= '3.11'"
 ]
 
 [dependency-groups]
@@ -149,12 +153,6 @@ features = ["pyo3/extension-module"]
 manifest-path = "rust/Cargo.toml"
 python-packages = ["multistorageclient", "multistorageclient_rust", "hydra_plugins"]
 
-[tool.pip-licenses]
-format = "markdown"
-order = "license"
-output-file = ".licenses.md"
-with-urls = true
-
 [tool.poetry]
 packages = [
     { include = "multistorageclient", from = "src" }