feat: add built-in caching via inputs

.github/workflows/test.yml

@@ -80,6 +80,41 @@ jobs:
       - name: Check binary exists
         run: deno_foo -V
 
+  test-setup-cache:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Deno
+        uses: ./
+        with:
+          cache: true
+          cache-hash: ${{ hashFiles('**/deno.lock') }}
+
+      - name: Download dependencies for cache
+        run: deno install --global --no-config npm:[email protected]
+
+  test-cache:
+    needs: test-setup-cache
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Deno
+        uses: ./
+        with:
+          cache: true
+          cache-hash: ${{ hashFiles('**/deno.lock') }}
+
+      - name: Run with cached dependencies
+        run: deno run --cached-only --no-config -RE npm:[email protected] "It works!"
+
   lint:
     runs-on: ubuntu-latest
     steps:

README.md

@@ -141,3 +141,23 @@ number.
 
 - run: echo "Deno version is ${{ steps.deno.outputs.deno-version }}"
 ```
+
+### Caching dependencies downloaded by Deno automatically
+
+Dependencies installed by Deno can be cached automatically, which is similar to
+the [`cache` option in `setup-node`](https://github.com/actions/setup-node).
+
+To enable the cache, use `cache: true`. It's recommended to also add the
+`cache-hash` property, to scope caches based on lockfile changes.
+
+```yaml
+- uses: denoland/setup-deno@v2
+  with:
+    cache: true
+    cache-hash: ${{ hashFiles('**/deno.lock') }}
+```
+
+> [!WARNING]
+> If an environment variable `DENO_DIR` is set for steps that run/download
+> dependencies, then `DENO_DIR` must also be set for the `denoland/setup-deno`
+> action, for the caching to work as intended.

action.yml

@@ -13,11 +13,20 @@ inputs:
   deno-binary-name:
     description: The name to use for the binary.
     default: "deno"
+  cache:
+    description: Cache downloaded modules & packages automatically in GitHub Actions cache.
+    default: "false"
+  cache-hash:
+    description: A hash used as part of the cache key. Use e.g. `$\{{ hashFiles('**/deno.lock') }}` to cache based on the lockfile contents.
 outputs:
+  cache-hit:
+    description: A boolean indicating whether the cache was hit.
   deno-version:
     description: "The Deno version that was installed."
   release-channel:
     description: "The release channel of the installed version."
 runs:
   using: "node20"
   main: "dist/main.mjs"
+  post: "dist/post.mjs"
+  post-if: always()

deno.json

@@ -14,6 +14,7 @@
     "build": "deno run -A scripts/build.ts"
   },
   "imports": {
+    "@actions/cache": "npm:@actions/cache@^4.0.3",
     "@actions/core": "npm:@actions/core@^1.11.1",
     "@actions/tool-cache": "npm:@actions/tool-cache@^2.0.2",
     "@types/node": "npm:@types/node@^22.15.0",