Sparse-checkout configuration persists across workflows on self-hosted runners

[nilmond010]

[Bug] Sparse-checkout settings from actions/checkout persist and affect subsequent workflows on self-hosted runners

Summary

When using actions/checkout with sparse-checkout on a self-hosted runner, the sparse-checkout Git configuration persists across subsequent jobs. This causes later workflows (that do not use sparse-checkout) to only check out the previously sparse file set instead of the full repository.

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Prerequisite

• A self-hosted GitHub Actions runner is configured and available.

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Steps to Reproduce

1. Run a workflow with sparse-checkout

   - name: Checkout specific file from sample-repo
     uses: actions/checkout@v4
     with:
       lfs: true
       repository: org-name/sample-repo
       token: ${{ secrets.SAMPLE_TOKEN }} # Contains a PAT
       path: sample-repo
       sparse-checkout: |
         sample-file.bak
       sparse-checkout-cone-mode: false
       clean: false

   Allow the workflow to complete.

2. Run a second workflow on the same self-hosted runner (no sparse-checkout):

   - uses: actions/checkout@v4
     with:
       clean: true

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Expected Behavior

The second workflow should check out the entire repository, unaffected by the sparse-checkout configuration from the previous workflow.

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Actual Behavior

• The second workflow:
  • Removes all files.
  • Only checks out the files that were previously specified in the sparse-checkout configuration from the first workflow.
• This indicates that core.sparseCheckout remains set to true in the runner’s Git configuration between jobs.

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Analysis

• The actions/checkout action modifies the runner’s Git config:

  git config core.sparseCheckout true

• On self-hosted runners, this configuration persists across jobs and workflows.
• Unless explicitly reset, future runs on that runner inherit the sparse-checkout state.

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Temporary Workaround

Manually disable sparse-checkout after using it:

- name: Disable sparse checkout
  run: git config core.sparseCheckout false
  continue-on-error: true

---

Proposed Fix

Ensure actions/checkout:

1. Resets core.sparseCheckout to false at the start of each execution.
2. Does not persist sparse-checkout state between runs on the same runner.

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Reproducibility

• 100% reproducible.
• Can be tested without relying on our workflow execution references.

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Environment

• actions/checkout: v4
• Runner type: Self-hosted
• OS: Windows

[stefansli]

We just stumbled upon the same problem (action Version 4.2.2). Here is our research:

• The issue is linked to the usage of non cone mode checkouts. In that case, core.sparseCheckout is enabled directly, without calling git sparse-checkout.
• At some point (we are not sure how this happens), extensions.worktreeConfig is enabled
• During git sparse-checkout disable, git sets core.sparseCheckout to false in .git/config.worktree!!!
• Afterwards, extensions.worktreeConfig is disabled:

  checkout/src/git-command-manager.ts

  Line 182 in ff7abcd

  await this.tryConfigUnset('extensions.worktreeConfig', false)

• This leaves behind a core.sparseCheckout=true in .git/config causing further checkouts in the worktree/repository to use the sparse configuration

I can think of two ways to solve this:

1. Switch

   checkout/src/git-command-manager.ts

   Line 182 in ff7abcd

   await this.tryConfigUnset('extensions.worktreeConfig', false)

   with Line 180, maybe ensure that core.sparseCheckout is false by explicitly setting it.
2. Don't set core.sparseCheckout manually but initialize the sparse checkout for non cone mode with git sparse-checkout aswell and trust that git is doing the correct thing.

[lokesh755]

Thanks for reporting this. We’ve confirmed the behavior and will be working on a fix so that actions/checkout properly restores the sparse-checkout state in the post step.