minor

Update hashFiles documentation reference

.github/workflows/workflow.yml

@@ -99,7 +99,7 @@ jobs:
       options: --dns 127.0.0.1
     services:
       squid-proxy:
-        image: datadog/squid:latest
+        image: ubuntu/squid:latest
         ports:
           - 3128:3128
     env:
@@ -122,7 +122,7 @@ jobs:
       options: --dns 127.0.0.1
     services:
       squid-proxy:
-        image: datadog/squid:latest
+        image: ubuntu/squid:latest
         ports:
           - 3128:3128
     env:

README.md

@@ -48,7 +48,7 @@ If you are using this inside a container, a POSIX-compliant `tar` needs to be in
 See [Skipping steps based on cache-hit](#skipping-steps-based-on-cache-hit) for info on using this output
 
 ### Cache scopes
-The cache is scoped to the key and branch. The default branch cache is available to other branches.
+The cache is scoped to the key, [version](#cache-version) and branch. The default branch cache is available to other branches.
 
 See [Matching a cache key](https://help.github.com/en/actions/configuring-and-managing-workflows/caching-dependencies-to-speed-up-workflows#matching-a-cache-key) for more info.
 
@@ -118,7 +118,7 @@ See [Examples](examples.md) for a list of `actions/cache` implementations for us
 
 A cache key can include any of the contexts, functions, literals, and operators supported by GitHub Actions.
 
-For example, using the [`hashFiles`](https://help.github.com/en/actions/reference/context-and-expression-syntax-for-github-actions#hashfiles) function allows you to create a new cache when dependencies change.
+For example, using the [`hashFiles`](https://docs.github.com/en/actions/learn-github-actions/expressions#hashfiles) function allows you to create a new cache when dependencies change.
 
 ```yaml
   - uses: actions/cache@v3
@@ -175,9 +175,13 @@ steps:
 
 
 ## Cache Version
-Cache version is unique for a combination of compression tool used for compression of cache (Gzip, Zstd, etc based on runner OS) and the path of directories being cached. If two caches have different versions, they are identified as unique cache entries. This also means that a cache created on `windows-latest` runner can't be restored on `ubuntu-latest` as cache `Version`s are different. 
+Cache version is a hash [generated](https://github.com/actions/toolkit/blob/500d0b42fee2552ae9eeb5933091fe2fbf14e72d/packages/cache/src/internal/cacheHttpClient.ts#L73-L90) for a combination of compression tool used (Gzip, Zstd, etc. based on the runner OS) and the `path` of directories being cached. If two caches have different versions, they are identified as unique caches while matching. This for example, means that a cache created on `windows-latest` runner can't be restored on `ubuntu-latest` as cache `Version`s are different. 
 
-Example: Below example will create 3 unique caches with same keys. Ubuntu and windows runners will use different compression technique and hence create two different caches. And `build-linux` will create two different caches as the `paths` are different.
+> Pro tip: [List caches](https://docs.github.com/en/rest/actions/cache#list-github-actions-caches-for-a-repository) API can be used to get the version of a cache. This can be helpful to troubleshoot cache miss due to version. 
+
+<details>
+  <summary>Example</summary>
+The workflow will create 3 unique caches with same keys. Ubuntu and windows runners will use different compression technique and hence create two different caches. And `build-linux` will create two different caches as the `paths` are different.
 
 ```yaml
 jobs:
@@ -224,6 +228,44 @@ jobs:
         if: steps.cache-primes.outputs.cache-hit != 'true'
         run: ./generate-primes -d prime-numbers
 ```
+</details>
+
+## Deleting caches
+We can not re-use caches from pull request branches in other branches like main, such caches can eat up the storage quota and hence causing thrashing on more useful branches like main. In order to resolve this issue, we can use [gh-actions-cache cli](https://github.com/actions/gh-actions-cache/) to delete caches. This workflow uses `gh-actions-cache` to delete all the caches created by all the pull requests. 
+
+```
+name: cleanup-caches
+on:
+  workflow_dispatch
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v3
+
+      - name: Cleanup
+        run: |
+          gh extension install actions/gh-actions-cache
+          
+          REPO=${{ github.repository }}
+
+          echo "Fetching list of cache key"
+          ## This will extract out all the cache keys for pull requests
+          cacheKeysForPR=$(gh actions-cache list -R $REPO | grep "refs/pull" | cut -d $'\t'  -f 1 )
+
+          ## Setting this to not fail the workflow while deleting duplicate cache keys. We can have same cache key for multiple branches based on the cache key generation.
+          set +e
+          echo "Deleting caches..."
+          for cacheKey in $cacheKeysForPR
+          do
+              gh actions-cache delete $cacheKey -R $REPO --confirm
+          done
+          echo "Done"
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+```
 
 ## Known practices and workarounds
 Following are some of the known practices/workarounds which community has used to fulfill specific requirements. You may choose to use them if suits your use case. Note these are not necessarily the only or the recommended solution.