Merge pull request #1017 from actions/kotewar/readme-updates-for-granular-control

Readme updates for granular control

README.md

@@ -2,12 +2,19 @@
 
 This action allows caching dependencies and build outputs to improve workflow execution time.
 
+In addition to this `cache` action, other two actions are also available
+
+[Restore action](./restore/README.md)
+
+[Save action](./save/README.md)
+
 [![Tests](https://github.com/actions/cache/actions/workflows/workflow.yml/badge.svg)](https://github.com/actions/cache/actions/workflows/workflow.yml)
 
 ## Documentation
 
 See ["Caching dependencies to speed up workflows"](https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows).
 
+
 ## What's New
 ### v3
 * Added support for caching from GHES 3.5.

restore/README.md

@@ -0,0 +1,131 @@
+# Restore action
+
+The restore action, as the name suggest, restores a cache. It acts similar to the`cache` action except that it doesn't have a post step to save the cache. This action can provide you a granular control to only restore a cache without having to necessarily save it.  It accepts the same set of inputs as the `cache` action.
+
+## Inputs
+
+* `path` - A list of files, directories, and wildcard patterns to cache and restore. See [`@actions/glob`](https://github.com/actions/toolkit/tree/main/packages/glob) for supported patterns.
+* `key` - String used while saving cache for restoring the cache
+* `restore-keys` - An ordered list of prefix-matched keys to use for restoring stale cache if no cache hit occurred for key.
+
+## Outputs
+
+* `cache-hit` - A boolean value to indicate an exact match was found for the key. 
+* `cache-primary-key` - Cache primary key passed in the input to use in subsequent steps of the workflow.
+* `cache-matched-key` -  Key of the cache that was restored, it could either be the primary key on cache-hit or a partial/complete match of one of the restore keys.
+
+> **Note**
+`cache-hit` will be set to `true` only when cache hit occurs for the exact `key` match. For a partial key match via `restore-keys` or a cache miss, it will be set to `false`.
+
+### Environment Variables
+* `SEGMENT_DOWNLOAD_TIMEOUT_MINS` - Segment download timeout (in minutes, default `60`) to abort download of the segment if not completed in the defined number of minutes. [Read more](https://github.com/actions/cache/blob/main/workarounds.md#cache-segment-restore-timeout)
+
+## Use cases
+
+As this is a newly introduced action to give users more control in their workflows, below are some use cases where one can use this action.
+
+### Only restore cache
+
+In case you are using another workflow to create and save your cache that can be reused by other jobs in your repository, this action will take care of your restore only needs.
+
+```yaml
+steps:
+  - uses: actions/checkout@v3
+
+  - uses: actions/cache/restore@v3
+    id: cache
+    with:
+      path: path/to/dependencies
+      key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
+
+  - name: Install Dependencies
+    if: steps.cache.outputs.cache-hit != 'true'
+    run: /install.sh
+
+  - name: Build
+    run: /build.sh
+
+  - name: Publish package to public
+    run: /publish.sh
+```
+
+Once the cache is restored, this action won't run any post step to do post-processing like `actions/cache` and the rest of the workflow will run as usual.
+
+### Save intermediate private build artifacts
+
+In case of multi-module projects, where the built artifact of one project needs to be reused in subsequent child modules, the need of rebuilding the parent module again and again with every build can be eliminated. The `actions/cache` or `actions/cache/save` action can be used to build and save the parent module artifact once, and restored multiple times while building the child modules.
+
+
+#### Step 1 - Build the parent module and save it
+```yaml
+steps:
+  - uses: actions/checkout@v3
+
+  - name: Build
+    run: /build-parent-module.sh
+
+  - uses: actions/cache/save@v3
+    id: cache
+    with:
+      path: path/to/dependencies
+      key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
+```
+
+#### Step 2 - Restore the built artifact from cache using the same key and path
+```yaml
+steps:
+  - uses: actions/checkout@v3
+
+  - uses: actions/cache/restore@v3
+    id: cache
+    with:
+      path: path/to/dependencies
+      key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
+
+  - name: Install Dependencies
+    if: steps.cache.outputs.cache-hit != 'true'
+    run: /install.sh
+
+  - name: Build
+    run: /build-child-module.sh
+
+  - name: Publish package to public
+    run: /publish.sh
+```
+
+### Exit workflow on cache miss
+
+You can use the output of this action to exit the workflow on cache miss. This way you can restrict your workflow to only initiate the build when `cache-hit` occurs, in other words, cache with exact key is found.
+
+```yaml
+steps:
+  - uses: actions/checkout@v3
+
+  - uses: actions/cache/restore@v3
+    id: cache
+    with:
+      path: path/to/dependencies
+      key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
+
+  - name: Check cache hit
+    if: steps.cache.outputs.cache-hit != 'true'
+    run: exit 1
+
+  - name: Build
+    run: /build.sh
+```
+
+## Tips
+
+
+#### Reusing primary key and restored key in the save action
+
+Usually you may want to use same `key` in both actions/cache/restore` and `actions/cache/save` action. To achieve this, use `outputs` from the restore action to reuse the same primary key (or the key of the cache that was restored).
+
+#### Using restore action outputs to make save action behave just like the cache action
+
+The outputs `cache-primary-key` and `cache-matched-key` can be used to check if the restored cache is same as the given primary key. Alternatively, the `cache-hit` output can also be used to check if the restored was a complete match or a partially restored cache.
+
+#### Ensuring proper restores and save happen across the actions
+
+It is very important to use the same `key` and `path` that were used by either `actions/cache` or `actions/cache/save` while saving the cache. Learn more about cache key [naming](https://github.com/actions/cache#creating-a-cache-key) and [versioning](https://github.com/actions/cache#cache-version) here.

save/README.md

@@ -0,0 +1,84 @@
+# Save action
+
+The save action, as the name suggest, saves a cache. It acts similar to the `cache` action except that it doesn't necessarily first do a restore. This action can provide you a granular control to only save a cache without having to necessarily restore it, or to do a restore anywhere in the workflow job and not only in post phase.
+
+## Inputs
+
+* `key` - 'An explicit key for saving the cache'
+* `path` - 'A list of files, directories, and wildcard patterns to cache'
+* `upload-chunk-size` - 'The chunk size used to split up large files during upload, in bytes'
+
+## Outputs
+
+This action has no outputs.
+
+## Use cases
+
+
+### Only save cache
+
+In case you are using separate jobs for generating common artifacts and sharing them across different jobs, this action will help you with your save only needs.
+
+```yaml
+steps:
+  - uses: actions/checkout@v3
+
+  - name: Install Dependencies
+    if: steps.cache.outputs.cache-hit != 'true'
+    run: /install.sh
+
+  - name: Build common artifacts
+    run: /build.sh
+
+  - uses: actions/cache/save@v3
+    id: cache
+    with:
+      path: path/to/dependencies
+      key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
+```
+
+### Re-evaluate cache key while saving
+
+With save action, the key can now be re-evaluated while executing the action. This helps in cases where the lockfiles are generated during the build.
+
+Let's say we have a restore step that computes key at runtime
+
+```yaml
+uses: actions/cache/restore@v3
+id: restore-cache
+with:
+    key: cache-${{ hashFiles('**/lockfiles') }}
+```
+
+Case 1: Where an user would want to reuse the key as it is
+```yaml
+uses: actions/cache/save@v3
+with:
+    key: steps.restore-cache.output.key
+```
+
+Case 2: Where the user would want to re-evaluate the key
+```yaml
+uses: actions/cache/save@v3
+with:
+    key: npm-cache-${{hashfiles(package-lock.json)}}
+```
+
+### Always save cache
+
+There are instances where some flaky test cases would fail the entire workflow and users would get frustrated because the builds would run for hours and the cache couldn't get saved as the workflow failed in between. For such use-cases, users would now have the ability to use `actions/cache/save` action to save the cache by using `if: always()` condition. This way the cache will always be saved if generated, or a warning will be thrown that nothing is found on the cache path. Users can also use the `if` condition to only execute the `actions/cache/save` action depending on the output of the previous steps. This way they get more control on when to save the cache.
+
+```yaml
+steps:
+  - uses: actions/checkout@v3
+  .
+  . // restore if need be
+  .
+  - name: Build
+    run: /build.sh
+  - uses: actions/cache/save@v3
+    if: always() // or any other condition to invoke the save action
+    with:
+      path: path/to/dependencies
+      key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
+```