71 lines
4.4 KiB
Markdown
71 lines
4.4 KiB
Markdown
## Cache segment restore timeout
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A cache gets downloaded in multiple segments of fixed sizes (`1GB` for a `32-bit` runner and `2GB` for a `64-bit` runner). Sometimes, a segment download gets stuck which causes the workflow job to be stuck forever and fail. Version `v3.0.8` of `actions/cache` introduces a segment download timeout. The segment download timeout will allow the segment download to get aborted and hence allow the job to proceed with a cache miss.
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Default value of this timeout is 60 minutes and can be customized by specifying an [environment variable](https://docs.github.com/en/actions/learn-github-actions/environment-variables) named `SEGMENT_DOWNLOAD_TIMEOUT_MINS` with timeout value in minutes.
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## Update a cache
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A cache today is immutable and cannot be updated. But some use cases require the cache to be saved even though there was a "hit" during restore. To do so, use a `key` which is unique for every run and use `restore-keys` to restore the nearest cache. For example:
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```yaml
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- name: update cache on every commit
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uses: actions/cache@v3
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with:
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path: prime-numbers
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key: primes-${{ runner.os }}-${{ github.run_id }} # Can use time based key as well
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restore-keys: |
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primes-${{ runner.os }}
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```
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Please note that this will create a new cache on every run and hence will consume the cache [quota](./README.md#cache-limits).
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## Use cache across feature branches
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Reusing cache across feature branches is not allowed today to provide cache [isolation](https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows#restrictions-for-accessing-a-cache). However if both feature branches are from the default branch, a good way to achieve this is to ensure that the default branch has a cache. This cache will then be consumable by both feature branches.
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## Force deletion of caches overriding default cache eviction policy
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Caches have [branch scope restriction](https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows#restrictions-for-accessing-a-cache) in place. This means that if caches for a specific branch are using a lot of storage quota, it may result into more frequently used caches from `default` branch getting thrashed. For example, if there are many pull requests happening on a repo and are creating caches, these cannot be used in default branch scope but will still occupy a lot of space till they get cleaned up by [eviction policy](https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows#usage-limits-and-eviction-policy). But sometime we want to clean them up on a faster cadence so as to ensure default branch is not thrashing. In order to achieve this, [gh-actions-cache cli](https://github.com/actions/gh-actions-cache/) can be used to delete caches for specific branches.
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This workflow uses `gh-actions-cache` to delete all the caches created by a branch.
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<details>
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<summary>Example</summary>
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```yaml
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name: cleanup caches by a branch
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on:
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pull_request:
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types:
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- closed
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workflow_dispatch:
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jobs:
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cleanup:
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runs-on: ubuntu-latest
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steps:
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- name: Check out code
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uses: actions/checkout@v3
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- name: Cleanup
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run: |
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gh extension install actions/gh-actions-cache
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REPO=${{ github.repository }}
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BRANCH=${{ github.ref }}
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echo "Fetching list of cache key"
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cacheKeysForPR=$(gh actions-cache list -R $REPO -B $BRANCH | cut -f 1 )
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## Setting this to not fail the workflow while deleting cache keys.
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set +e
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echo "Deleting caches..."
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for cacheKey in $cacheKeysForPR
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do
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gh actions-cache delete $cacheKey -R $REPO -B $BRANCH --confirm
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done
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echo "Done"
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env:
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GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
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```
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</details>
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## Cross OS cache
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From `v3.2.1` cache is cross os compatible. This means that a cache created on `ubuntu-latest` can be used by `windows-latest` and vice versa. This is useful when you want to cache dependencies which is available on different the OSs. This will help reduce the consumption of the cache quota. Things to keep in mind:
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- Only cache those files which are compatible across OSs.
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- Don't cache symlinks as they work differently on different OSs so would cause issues during cache restore.
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- Put runner OS in the cache key if that cache is not ment to be used across OSs. |