Why does actions/cache restore a cache but still show a cache miss?

[Hiteshnp65]

🏷️ Discussion Type

Bug

💬 Feature/Topic Area

ARC (Actions Runner Controller)

Discussion Details

I’m trying to understand how cache keys and restore keys work in GitHub Actions.

Sometimes a workflow shows a cache miss for the exact key, but then restores files using a restore-keys prefix. In that situation, does GitHub consider it a cache hit or a cache miss?

Also, if the dependencies have changed but the cache key stays the same, what is the recommended way to make sure the workflow doesn't keep restoring an outdated dependency cache?

I’ve checked the Actions cache documentation but I’m still a little confused about how exact matches, partial matches, and cache invalidation work together.

[github-actions[bot]]

💬 Your Product Feedback Has Been Submitted 🎉

Thank you for taking the time to share your insights with us! Your feedback is invaluable as we build a better GitHub experience for all our users.

Here's what you can expect moving forward ⏩

• Your input will be carefully reviewed and cataloged by members of our product teams. 
  • Due to the high volume of submissions, we may not always be able to provide individual responses.
  • Rest assured, your feedback will help chart our course for product improvements.
• Other users may engage with your post, sharing their own perspectives or experiences. 
• GitHub staff may reach out for further clarification or insight. 
  • We may 'Answer' your discussion if there is a current solution, workaround, or roadmap/changelog post related to the feedback.

Where to look to see what's shipping 👀

• Read the Changelog for real-time updates on the latest GitHub features, enhancements, and calls for feedback.
• Explore our Product Roadmap, which details upcoming major releases and initiatives.

What you can do in the meantime 💻

• Upvote and comment on other user feedback Discussions that resonate with you.
• Add more information at any point! Useful details include: use cases, relevant labels, desired outcomes, and any accompanying screenshots.

As a member of the GitHub community, your participation is essential. While we can't promise that every suggestion will be implemented, we want to emphasize that your feedback is instrumental in guiding our decisions and priorities.

Thank you once again for your contribution to making GitHub even better! We're grateful for your ongoing support and collaboration in shaping the future of our platform. ⭐

[MihaiCulbida]

Hi. Hope this helps!
A restore-keys match is still considered a cache miss for the exact key, even though GitHub can restore a partial matching cache.
If your dependencies change, it’s a good idea to include a hash of your lockfile (for example, hashFiles('**/package-lock.json')) in the cache key. This way, the key changes when the dependencies change, preventing an outdated cache from being reused.
Hope this clears things up. Good luck!