No default UV_CACHE_DIR on selfhosted runners (#380)

Closes: #371

Author: eifinger

.github/workflows/test.yml

@@ -408,6 +408,30 @@ jobs:
         env:
           CACHE_HIT: ${{ steps.restore.outputs.cache-hit }}
 
+  test-cache-local:
+    strategy:
+      matrix:
+        inputs:
+          - os: ubuntu-latest
+            expected-cache-dir: "/home/runner/work/_temp/setup-uv-cache"
+          - os: windows-latest
+            expected-cache-dir: "D:\\a\\_temp\\setup-uv-cache"
+          - os: selfhosted-ubuntu-arm64
+            expected-cache-dir: "/home/ubuntu/.cache/uv"
+    runs-on: ${{ matrix.inputs.os }}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup with cache
+        uses: ./
+        with:
+          cache-suffix: ${{ github.run_id }}-${{ github.run_attempt }}-test-cache-local
+      - run: |
+          if [ "$UV_CACHE_DIR" != "${{ matrix.inputs.expected-cache-dir }}" ]; then
+            echo "UV_CACHE_DIR is not set to the expected value: $UV_CACHE_DIR"
+            exit 1
+          fi
+        shell: bash
+
   test-setup-cache-local:
     runs-on: selfhosted-ubuntu-arm64
     steps:
@@ -521,6 +545,7 @@ jobs:
       - test-python-version
       - test-activate-environment
       - test-musl
+      - test-cache-local
       - test-restore-cache
       - test-restore-cache-requirements-txt
       - test-restore-cache-dependency-glob

dist/save-cache/index.js

@@ -64,12 +64,18 @@ function getCacheLocalPath(): string {
   if (cacheLocalPathInput !== "") {
     return expandTilde(cacheLocalPathInput);
   }
-  if (process.env.RUNNER_TEMP !== undefined) {
-    return `${process.env.RUNNER_TEMP}${path.sep}setup-uv-cache`;
+  if (process.env.RUNNER_ENVIRONMENT === "github-hosted") {
+    if (process.env.RUNNER_TEMP !== undefined) {
+      return `${process.env.RUNNER_TEMP}${path.sep}setup-uv-cache`;
+    }
+    throw Error(
+      "Could not determine UV_CACHE_DIR. Please make sure RUNNER_TEMP is set or provide the cache-local-path input",
+    );
+  }
+  if (process.platform === "win32") {
+    return `${process.env.APPDATA}${path.sep}uv${path.sep}cache`;
   }
-  throw Error(
-    "Could not determine UV_CACHE_DIR. Please make sure RUNNER_TEMP is set or provide the cache-local-path input",
-  );
+  return `${process.env.HOME}${path.sep}.cache${path.sep}uv`;
 }
 
 function expandTilde(input: string): string {