fix: add OS version to cache key to prevent binary incompatibility (#716)

## Summary

- Adds OS name and version (e.g., `ubuntu-22.04`, `macos-14`,
`windows-2022`) to cache keys to prevent binary incompatibility when
GitHub updates runner images
- Fixes issue where cached uv binaries compiled against older
glibc/library versions fail on newer runner OS versions

## Changes

- Added `getOSNameVersion()` function to `src/utils/platforms.ts` with
OS-specific detection for Linux (via `/etc/os-release`), macOS (Darwin
kernel version mapping), and Windows
- Updated cache key format to include OS version, bumped `CACHE_VERSION`
to `"2"`
- Added `cache-key` output to expose the generated cache key for
debugging
- Added `test-cache-key-os-version` job testing across multiple OS
versions
- Updated `docs/caching.md` with cache key documentation

Closes #703

Author: eifinger

.github/workflows/test.yml

@@ -385,10 +385,60 @@ jobs:
         with:
           persist-credentials: false
       - name: Install latest version
+        id: setup-uv
         uses: ./
+        with:
+          enable-cache: true
+      - name: Verify cache key contains alpine
+        run: |
+          echo "Cache key: $CACHE_KEY"
+          if echo "$CACHE_KEY" | grep -qv "alpine"; then
+            echo "Cache key does not contain 'alpine'"
+            exit 1
+          fi
+        shell: sh
+        env:
+          CACHE_KEY: ${{ steps.setup-uv.outputs.cache-key }}
       - run: uv sync
         working-directory: __tests__/fixtures/uv-project
 
+  test-cache-key-os-version:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        include:
+          - os: ubuntu-22.04
+            expected-os: "ubuntu-22.04"
+          - os: ubuntu-24.04
+            expected-os: "ubuntu-24.04"
+          - os: macos-14
+            expected-os: "macos-14"
+          - os: macos-15
+            expected-os: "macos-15"
+          - os: windows-2022
+            expected-os: "windows-2022"
+          - os: windows-2025
+            expected-os: "windows-2025"
+    steps:
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          persist-credentials: false
+      - name: Setup uv
+        id: setup-uv
+        uses: ./
+        with:
+          enable-cache: true
+      - name: Verify cache key contains OS version
+        run: |
+          echo "Cache key: $CACHE_KEY"
+          if [[ "$CACHE_KEY" != *"${{ matrix.expected-os }}"* ]]; then
+            echo "Cache key does not contain expected OS version: ${{ matrix.expected-os }}"
+            exit 1
+          fi
+        shell: bash
+        env:
+          CACHE_KEY: ${{ steps.setup-uv.outputs.cache-key }}
+
   test-setup-cache:
     runs-on: ${{ matrix.os }}
     strategy:
@@ -1002,6 +1052,7 @@ jobs:
       - test-python-version
       - test-activate-environment
       - test-musl
+      - test-cache-key-os-version
       - test-cache-local
       - test-cache-local-cache-disabled
       - test-cache-local-cache-disabled-but-explicit-path

action.yml

@@ -89,6 +89,8 @@ outputs:
     description: "The path to the installed uvx binary."
   cache-hit:
     description: "A boolean value to indicate a cache entry was found"
+  cache-key:
+    description: "The cache key used for storing/restoring the cache"
   venv:
     description: "Path to the activated venv if activate-environment is true"
 runs:

dist/save-cache/index.js

@@ -2,6 +2,34 @@
 
 This document covers all caching-related configuration options for setup-uv.
 
+## Cache key
+
+The cache key is automatically generated based on:
+
+- **Architecture**: CPU architecture (e.g., `x86_64`, `aarch64`)
+- **Platform**: OS platform type (e.g., `unknown-linux-gnu`, `unknown-linux-musl`, `apple-darwin`,
+  `pc-windows-msvc`)
+- **OS version**: OS name and version (e.g., `ubuntu-22.04`, `macos-14`, `windows-2022`)
+- **Python version**: The Python version in use
+- **Cache options**: Whether pruning and Python caching are enabled
+- **Dependency hash**: Hash of files matching `cache-dependency-glob`
+- **Suffix**: Optional `cache-suffix` if provided
+
+Including the OS version ensures that caches are not shared between different OS versions,
+preventing binary incompatibility issues when runner images change.
+
+The computed cache key is available as the `cache-key` output:
+
+```yaml
+- name: Setup uv
+  id: setup-uv
+  uses: astral-sh/setup-uv@v7
+  with:
+    enable-cache: true
+- name: Print cache key
+  run: echo "Cache key: ${{ steps.setup-uv.outputs.cache-key }}"
+```
+
 ## Enable caching
 
 > [!NOTE]

dist/setup/index.js

@@ -13,15 +13,16 @@ import {
   restoreCache as shouldRestoreCache,
   workingDirectory,
 } from "../utils/inputs";
-import { getArch, getPlatform } from "../utils/platforms";
+import { getArch, getOSNameVersion, getPlatform } from "../utils/platforms";
 
 export const STATE_CACHE_KEY = "cache-key";
 export const STATE_CACHE_MATCHED_KEY = "cache-matched-key";
-const CACHE_VERSION = "1";
+const CACHE_VERSION = "2";
 
 export async function restoreCache(): Promise<void> {
   const cacheKey = await computeKeys();
   core.saveState(STATE_CACHE_KEY, cacheKey);
+  core.setOutput("cache-key", cacheKey);
 
   if (!shouldRestoreCache) {
     core.info("restore-cache is false. Skipping restore cache step.");
@@ -72,9 +73,10 @@ async function computeKeys(): Promise<string> {
   const suffix = cacheSuffix ? `-${cacheSuffix}` : "";
   const pythonVersion = await getPythonVersion();
   const platform = await getPlatform();
+  const osNameVersion = getOSNameVersion();
   const pruned = pruneCache ? "-pruned" : "";
   const python = cachePython ? "-py" : "";
-  return `setup-uv-${CACHE_VERSION}-${getArch()}-${platform}-${pythonVersion}${pruned}${python}${cacheDependencyPathHash}${suffix}`;
+  return `setup-uv-${CACHE_VERSION}-${getArch()}-${platform}-${osNameVersion}-${pythonVersion}${pruned}${python}${cacheDependencyPathHash}${suffix}`;
 }
 
 async function getPythonVersion(): Promise<string> {