Use uv Python keys for runtime IDs

.github/workflows/test.yml

@@ -386,29 +386,21 @@ jobs:
         shell: bash
       - name: Verify Python version outputs and cache key
         run: |
-          expected=$(python -I - <<'PY'
+          expected_prefix=$(python -I - <<'PY'
           import platform
           import sys
           import sysconfig
 
-          if sys.implementation.name == "cpython":
-              runtime = f"cpython-{platform.python_version()}"
-          else:
-              version = sys.implementation.version
-              implementation_version = f"{version.major}.{version.minor}.{version.micro}"
-              suffix = {"alpha": "a", "beta": "b", "candidate": "rc", "final": ""}[version.releaselevel]
-              if suffix:
-                  implementation_version += f"{suffix}{version.serial}"
-              runtime = f"{sys.implementation.name}-{implementation_version}-python-{platform.python_version()}"
+          runtime = f"{sys.implementation.name}-{platform.python_version()}"
           if sysconfig.get_config_var("Py_GIL_DISABLED") == 1:
-              runtime += "-freethreaded"
-          print(runtime)
+              runtime += "+freethreaded"
+          print(f"{runtime}-")
           PY
           )
-          if [ "$PYTHON_RUNTIME_ID" != "$expected" ]; then
-            echo "Wrong Python runtime ID: $PYTHON_RUNTIME_ID (expected $expected)"
-            exit 1
-          fi
+          case "$PYTHON_RUNTIME_ID" in
+            "$expected_prefix"*) ;;
+            *) echo "Wrong Python runtime ID: $PYTHON_RUNTIME_ID (expected prefix $expected_prefix)"; exit 1 ;;
+          esac
           if [ "$PYTHON_VERSION" != "$PYTHON_REQUEST" ]; then
             echo "Wrong requested Python version: $PYTHON_VERSION"
             exit 1
@@ -489,10 +481,10 @@ jobs:
         shell: bash
       - name: Verify Python runtime ID from custom venv
         run: |
-          if [ "$PYTHON_RUNTIME_ID" != "cpython-3.13.1-freethreaded" ]; then
-            echo "Wrong Python runtime ID: $PYTHON_RUNTIME_ID"
-            exit 1
-          fi
+          case "$PYTHON_RUNTIME_ID" in
+            cpython-3.13.1+freethreaded-*) ;;
+            *) echo "Wrong Python runtime ID: $PYTHON_RUNTIME_ID"; exit 1 ;;
+          esac
         shell: bash
         env:
           PYTHON_RUNTIME_ID: ${{ steps.setup-uv.outputs.python-runtime-id }}

README.md

@@ -138,8 +138,8 @@ Have a look under [Advanced Configuration](#advanced-configuration) for detailed
 - `cache-hit`: A boolean value to indicate a cache entry was found.
 - `venv`: Path to the activated venv if activate-environment is true.
 - `python-version`: The Python version that was set.
-- `python-runtime-id`: An opaque identifier for the activated venv's Python runtime, including
-  implementation, full version, and free-threaded build information. Useful as a cache-key component.
+- `python-runtime-id`: An opaque identifier reported by uv for the activated venv's Python runtime, including
+  implementation, full Python version, and free-threaded build information. Useful as a cache-key component.
   Empty when `activate-environment` is false. The action fails if the activated runtime cannot be determined.
 - `python-cache-hit`: A boolean value to indicate the Python cache entry was found.
 

__tests__/utils/python-runtime.test.ts

@@ -1,13 +1,11 @@
-import { join } from "node:path";
 import { promisify } from "node:util";
-import { afterEach, beforeEach, expect, it, jest } from "@jest/globals";
+import { beforeEach, expect, it, jest } from "@jest/globals";
 import { createSetupInputs } from "../helpers/setup-inputs";
 
 const mockExecFile =
   jest.fn<
     (...args: unknown[]) => Promise<{ stdout: string; stderr: string }>
   >();
-const originalPlatform = process.platform;
 const inputs = createSetupInputs({
   activateEnvironment: true,
   pythonVersion: "3.15t",
@@ -20,28 +18,15 @@ jest.unstable_mockModule("node:child_process", () => ({
 
 const { getPythonRuntimeId } = await import("../../src/utils/python-runtime");
 
-function mockRuntime(overrides: Record<string, unknown> = {}) {
-  mockExecFile.mockResolvedValue({
-    stderr: "",
-    stdout: `${JSON.stringify({
-      freethreaded: false,
-      implementation: "cpython",
-      implementationVersion: [3, 13, 1, "final", 0],
-      pythonVersion: "3.13.1",
-      ...overrides,
-    })}\r\n`,
-  });
-}
-
 beforeEach(() => {
   mockExecFile.mockReset();
-  mockRuntime();
-});
-afterEach(() => {
-  Object.defineProperty(process, "platform", { value: originalPlatform });
+  mockExecFile.mockResolvedValue({
+    stderr: "",
+    stdout: '[{"key":"cpython-3.13.1-linux-x86_64-gnu"}]\r\n',
+  });
 });
 
-it("does not query Python without environment activation", async () => {
+it("does not query uv without environment activation", async () => {
   expect(
     await getPythonRuntimeId({ ...inputs, activateEnvironment: false }),
   ).toBe("");
@@ -49,62 +34,47 @@ it("does not query Python without environment activation", async () => {
 });
 
 it.each([
-  ["3.13.1", false, "cpython-3.13.1"],
-  ["3.15.0a1", false, "cpython-3.15.0a1"],
-  ["3.15.0b2", false, "cpython-3.15.0b2"],
-  ["3.15.0rc1", false, "cpython-3.15.0rc1"],
-  ["3.15.0rc1", true, "cpython-3.15.0rc1-freethreaded"],
-  ["3.15.0rc2", true, "cpython-3.15.0rc2-freethreaded"],
-  ["3.15.0", true, "cpython-3.15.0-freethreaded"],
-])("formats CPython %s, free-threading=%s", async (version, free, expected) => {
-  mockRuntime({ freethreaded: free, pythonVersion: version });
-  expect(await getPythonRuntimeId(inputs)).toBe(expected);
-});
-
-it.each([
-  ["pypy", [7, 3, 23, "final", 0], "pypy-7.3.23"],
-  ["pypy", [7, 3, 24, "final", 0], "pypy-7.3.24"],
-  ["pypy", [7, 3, 24, "alpha", 1], "pypy-7.3.24a1"],
-  ["pypy", [7, 3, 24, "beta", 2], "pypy-7.3.24b2"],
-  ["pypy", [7, 3, 24, "candidate", 3], "pypy-7.3.24rc3"],
-  ["graalpy", [25, 0, 0, "final", 0], "graalpy-25.0.0"],
-])("formats %s implementation version %j", async (name, version, expected) => {
-  mockRuntime({
-    implementation: name,
-    implementationVersion: version,
-    pythonVersion: "3.11.15",
+  "cpython-3.13.1-linux-x86_64-gnu",
+  "cpython-3.15.0rc1+freethreaded-macos-aarch64-none",
+  "cpython-3.15.0rc2+freethreaded-windows-x86_64-none",
+  "pypy-3.11.15-linux-x86_64-gnu",
+])("returns uv's opaque runtime key unchanged: %s", async (key) => {
+  mockExecFile.mockResolvedValue({
+    stderr: "",
+    stdout: `${JSON.stringify([{ key }])}\r\n`,
   });
-  expect(await getPythonRuntimeId(inputs)).toBe(`${expected}-python-3.11.15`);
+  expect(await getPythonRuntimeId(inputs)).toBe(key);
 });
 
-it.each([
-  ["linux", 'a "quoted" venv', "bin/python"],
-  ["darwin", "custom venv", "bin/python"],
-  ["win32", "custom venv", "Scripts/python.exe"],
-])("passes the venv executable directly on %s", async (platform, name, exe) => {
-  Object.defineProperty(process, "platform", { value: platform });
-  const venvPath = join("/runner temp", name);
-  await getPythonRuntimeId({ ...inputs, venvPath });
-  expect(mockExecFile).toHaveBeenCalledWith(
-    join(venvPath, exe),
-    ["-I", "-c", expect.any(String)],
-    { encoding: "utf8" },
-  );
-});
+it.each(['/runner temp/a "quoted" venv', "C:\\runner temp\\custom venv"])(
+  "queries the exact venv directory: %s",
+  async (venvPath) => {
+    await getPythonRuntimeId({ ...inputs, venvPath });
+    expect(mockExecFile).toHaveBeenCalledWith(
+      "uv",
+      [
+        "python",
+        "list",
+        venvPath,
+        "--only-installed",
+        "--output-format",
+        "json",
+      ],
+      { encoding: "utf8" },
+    );
+  },
+);
 
 it.each([
-  new Error("interpreter missing"),
-  "",
+  new Error("uv failed"),
   "not JSON",
   "null",
   "{}",
-  JSON.stringify({
-    freethreaded: false,
-    implementation: "pypy",
-    implementationVersion: [7, 3, 24, "unknown", 0],
-    pythonVersion: "3.11.15",
-  }),
-])("rejects interpreter failure or invalid metadata: %s", async (result) => {
+  "[]",
+  '[{"key":""}]',
+  '[{"key":123}]',
+  '[{"key":"first"},{"key":"second"}]',
+])("rejects uv failure or invalid results: %s", async (result) => {
   if (result instanceof Error) {
     mockExecFile.mockRejectedValue(result);
   } else {

action.yml

@@ -108,7 +108,7 @@ outputs:
   python-version:
     description: "The Python version that was set."
   python-runtime-id:
-    description: "An opaque identifier for the activated venv's Python runtime, including implementation, full version, and free-threaded build information. Empty when activate-environment is false. The action fails if the activated runtime cannot be determined."
+    description: "An opaque identifier reported by uv for the activated venv's Python runtime, including implementation, full Python version, and free-threaded build information. Empty when activate-environment is false. The action fails if the activated runtime cannot be determined."
   python-cache-hit:
     description: "A boolean value to indicate the Python cache entry was found"
 runs:

dist/setup/index.cjs

@@ -102068,53 +102068,30 @@ function getResolutionStrategy() {
 
 // src/utils/python-runtime.ts
 var import_node_child_process = require("node:child_process");
-var import_node_path2 = require("node:path");
 var import_node_util4 = require("node:util");
 var execFileAsync = (0, import_node_util4.promisify)(import_node_child_process.execFile);
-var PYTHON_RUNTIME_QUERY = `
-import json
-import platform
-import sys
-import sysconfig
-
-print(json.dumps({
-    "implementation": sys.implementation.name,
-    "implementationVersion": list(sys.implementation.version),
-    "pythonVersion": platform.python_version(),
-    "freethreaded": sysconfig.get_config_var("Py_GIL_DISABLED") == 1,
-}))
-`;
-function formatRuntimeId(runtime) {
-  if (typeof runtime.implementation !== "string" || runtime.implementation === "" || typeof runtime.pythonVersion !== "string" || runtime.pythonVersion === "" || typeof runtime.freethreaded !== "boolean") {
-    throw new Error("Invalid Python runtime metadata");
-  }
-  let id = `cpython-${runtime.pythonVersion}`;
-  if (runtime.implementation !== "cpython") {
-    const [major2, minor2, micro, releaseLevel, serial] = runtime.implementationVersion;
-    const suffixes = { alpha: "a", beta: "b", candidate: "rc", final: "" };
-    const suffix = suffixes[releaseLevel];
-    if (suffix === void 0 || ![major2, minor2, micro, serial].every(
-      (part) => Number.isInteger(part) && part >= 0
-    )) {
-      throw new Error("Invalid Python implementation version");
-    }
-    const implementationVersion = `${major2}.${minor2}.${micro}${suffix}${suffix ? serial : ""}`;
-    id = `${runtime.implementation}-${implementationVersion}-python-${runtime.pythonVersion}`;
-  }
-  return runtime.freethreaded ? `${id}-freethreaded` : id;
-}
 async function getPythonRuntimeId(inputs) {
   if (!inputs.activateEnvironment) {
     return "";
   }
-  const pythonPath = process.platform === "win32" ? (0, import_node_path2.join)(inputs.venvPath, "Scripts", "python.exe") : (0, import_node_path2.join)(inputs.venvPath, "bin", "python");
   try {
     const { stdout } = await execFileAsync(
-      pythonPath,
-      ["-I", "-c", PYTHON_RUNTIME_QUERY],
+      "uv",
+      [
+        "python",
+        "list",
+        inputs.venvPath,
+        "--only-installed",
+        "--output-format",
+        "json"
+      ],
       { encoding: "utf8" }
     );
-    return formatRuntimeId(JSON.parse(stdout));
+    const pythons = JSON.parse(stdout);
+    if (!Array.isArray(pythons) || pythons.length !== 1 || typeof pythons[0]?.key !== "string" || pythons[0].key === "") {
+      throw new Error("Expected one installed Python with a runtime key");
+    }
+    return pythons[0].key;
   } catch (error2) {
     throw new Error(
       `Failed to identify the activated environment's Python runtime: ${error2 instanceof Error ? error2.message : String(error2)}`,

docs/environment-and-tools.md

@@ -18,7 +18,7 @@ This allows directly using it in later steps:
 By default, the venv is created at `.venv` inside the `working-directory`.
 
 With `activate-environment: true`, the `python-runtime-id` output identifies the
-venv's Python runtime. This is an opaque identifier that users of the action
+venv's Python runtime as reported by uv. This is an opaque identifier that users of the action
 can use as a cache key if necessary; users should not assume anything about
 the stability or structure of the identifier itself.
 

src/utils/python-runtime.ts

@@ -1,82 +1,37 @@
 import { execFile } from "node:child_process";
-import { join } from "node:path";
 import { promisify } from "node:util";
 import type { SetupInputs } from "./inputs";
 
 const execFileAsync = promisify(execFile);
 
-const PYTHON_RUNTIME_QUERY = `
-import json
-import platform
-import sys
-import sysconfig
-
-print(json.dumps({
-    "implementation": sys.implementation.name,
-    "implementationVersion": list(sys.implementation.version),
-    "pythonVersion": platform.python_version(),
-    "freethreaded": sysconfig.get_config_var("Py_GIL_DISABLED") == 1,
-}))
-`;
-
-type ReleaseLevel = "alpha" | "beta" | "candidate" | "final";
-
-interface PythonRuntime {
-  implementation: string;
-  implementationVersion: [number, number, number, ReleaseLevel, number];
-  pythonVersion: string;
-  freethreaded: boolean;
-}
-
-function formatRuntimeId(runtime: PythonRuntime): string {
-  if (
-    typeof runtime.implementation !== "string" ||
-    runtime.implementation === "" ||
-    typeof runtime.pythonVersion !== "string" ||
-    runtime.pythonVersion === "" ||
-    typeof runtime.freethreaded !== "boolean"
-  ) {
-    throw new Error("Invalid Python runtime metadata");
-  }
-
-  let id = `cpython-${runtime.pythonVersion}`;
-  if (runtime.implementation !== "cpython") {
-    const [major, minor, micro, releaseLevel, serial] =
-      runtime.implementationVersion;
-    const suffixes = { alpha: "a", beta: "b", candidate: "rc", final: "" };
-    const suffix = suffixes[releaseLevel];
-    if (
-      suffix === undefined ||
-      ![major, minor, micro, serial].every(
-        (part) => Number.isInteger(part) && part >= 0,
-      )
-    ) {
-      throw new Error("Invalid Python implementation version");
-    }
-    const implementationVersion = `${major}.${minor}.${micro}${suffix}${suffix ? serial : ""}`;
-    id = `${runtime.implementation}-${implementationVersion}-python-${runtime.pythonVersion}`;
-  }
-
-  return runtime.freethreaded ? `${id}-freethreaded` : id;
-}
-
 export async function getPythonRuntimeId(inputs: SetupInputs): Promise<string> {
   if (!inputs.activateEnvironment) {
     return "";
   }
 
-  const pythonPath =
-    process.platform === "win32"
-      ? join(inputs.venvPath, "Scripts", "python.exe")
-      : join(inputs.venvPath, "bin", "python");
-
   try {
     const { stdout } = await execFileAsync(
-      pythonPath,
-      ["-I", "-c", PYTHON_RUNTIME_QUERY],
+      "uv",
+      [
+        "python",
+        "list",
+        inputs.venvPath,
+        "--only-installed",
+        "--output-format",
+        "json",
+      ],
       { encoding: "utf8" },
     );
-    return formatRuntimeId(JSON.parse(stdout));
+    const pythons = JSON.parse(stdout);
+    if (
+      !Array.isArray(pythons) ||
+      pythons.length !== 1 ||
+      typeof pythons[0]?.key !== "string" ||
+      pythons[0].key === ""
+    ) {
+      throw new Error("Expected one installed Python with a runtime key");
+    }
+    return pythons[0].key;
   } catch (error) {
     throw new Error(
       `Failed to identify the activated environment's Python runtime: ${error instanceof Error ? error.message : String(error)}`,