Best Caching Solutions for CI/CD Ephemeral Runners

Since you're using Kubernetes to host your runners, you might want to leverage GitLab CI's caching features. Deploy Garage-S3 in your cluster, create a bucket for caching, and configure your runner to use that.

Using an artifact repository like Nexus can really streamline your caching process. There's a free version available, and if you proxy your Maven and npm dependencies through it, it'll cache them for you automatically.

If you're running on AWS, consider using S3-backed caching solutions. You can check out some of the options available like the S3-backed actions or caching replacements that are pretty handy for CI/CD processes.

Caching with ephemeral runners can get complicated, so having a central artifact repository like Nexus or a S3-backed cache can simplify things a lot. By directing all your runners to it, you can manage dependencies more effectively. Are you using GitHub Actions for your runners, or something custom?

If you're packing your code into an immutable Docker image, you can take advantage of Docker's caching capabilities. Just remember that alongside pushing your image to a container registry, you should also push the cache. This will help speed up your next build, depending on the CI/CD tool you're using. You may also want to consider setting up cache logic tailored to your specific needs.