aqua-installer's caching

docs/products/aqua-installer.md

@@ -95,3 +95,51 @@ policy_allow | `""` | aqua >= `v2.3.0`. If this is `"true"`, `aqua policy allow`
 Please see [action.yaml](https://github.com/aquaproj/aqua-installer/blob/main/action.yaml) too.
 
 Nothing.
+
+### :bulb: Caching
+
+[#428](https://github.com/aquaproj/aqua-installer/issues/428)
+
+aqua-installer doesn't support caching, but you can cache packages and registries using `actions/cache`.
+
+e.g.
+
+```yaml
+- uses: actions/cache@v3.3.1
+  with:
+    path: ~/.local/share/aquaproj-aqua
+    key: v1-aqua-installer-${{runner.os}}-${{runner.arch}}-${{hashFiles('aqua.yaml')}}
+    restore-keys: |
+      v1-aqua-installer-${{runner.os}}-${{runner.arch}}-
+- uses: aquaproj/aqua-installer@v2.1.1
+  with:
+    aqua_version: v2.6.0
+```
+
+Please fix `actions/cache`'s parameters properly.
+If you [split `aqua.yaml` using import](/docs/guides/split-config) or use local Registries, you may have to add hashes of them to key and restore-keys.
+
+e.g.
+
+```yaml
+- uses: actions/cache@v3.3.1
+  with:
+    path: ~/.local/share/aquaproj-aqua
+    key: v1-aqua-installer-${{runner.os}}-${{runner.arch}}-${{hashFiles('.aqua/*.yaml')}} # Change key
+    restore-keys: |
+      v1-aqua-installer-${{runner.os}}-${{runner.arch}}-
+```
+
+aqua-installer runs aqua with [-l](https://aquaproj.github.io/docs/tutorial/install-only-link) option by default, so packages that aren't run in the workflow aren't cached.
+If you want to cache all packages, please set `aqua_opts` to unset `-l` option.
+
+```yaml
+- uses: aquaproj/aqua-installer@v2.1.1
+  with:
+    aqua_version: v2.6.0
+    aqua_opts: "" # Unset `-l` option
+```
+
+But if `-l` is unset, aqua installs packages that aren't run in the workflow uselessly.
+
+So it is up to you that whether and how you cache packages.