make: use Docker named volumes for ~21x faster local linting (Mac OS)

[Roasbeef]

This commit optimizes Docker cache mounting for the linter with a CI-aware strategy:

Local development (macOS/Windows): Uses Docker named volumes which keep data inside Docker's native Linux filesystem, avoiding the slow host-syncing overhead of bind mounts. This yields ~21x faster linting on warm cache.

CI (GitHub Actions): Uses bind mounts to host paths (~/.cache/go-build, ~/go/pkg/mod) that GitHub Actions already caches via the setup-go action. This ensures CI benefits from cached dependencies across runs.

The Makefile detects CI mode via the CI environment variable that GitHub Actions sets automatically.

Local benchmark results:

• Cold run (empty cache): ~2m 28s
• Warm run (cached): ~11s (~21x faster)

Key improvements in warm runs:

• Go packages loading: 1m 58s → 5.6s
• Linters execution: 20.5s → 2.7s
• Total execution: 2m 20s → 8.6s

This should keep CI the same, while dramatically speeding up lint time locally (at least on mac).

[gemini-code-assist]

Summary of Changes

Hello @Roasbeef, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a strategic optimization to the Docker-based linting process, significantly improving the local development experience on macOS and Windows by leveraging Docker named volumes for caching. This change drastically reduces linting times for warm caches without impacting the efficiency of CI pipelines, which continue to utilize existing GitHub Actions caching mechanisms. The Makefile has been updated to dynamically apply the correct caching strategy based on the execution environment.

Highlights

• Optimized Docker Cache Mounting: Implemented a dual-strategy for Docker cache mounting in the linter, differentiating between CI and local development environments to maximize performance.
• Significant Local Performance Boost: Switched local linting to use Docker named volumes, resulting in approximately 21x faster warm cache linting on macOS/Windows by avoiding slow host-syncing overhead.
• CI Cache Preservation: Maintained existing CI performance by continuing to use bind mounts to host paths that GitHub Actions already caches, ensuring no regression in CI build times.
• CI Detection: The Makefile now intelligently detects the CI environment using the CI environment variable to apply the appropriate caching strategy automatically.

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[gemini-code-assist]

Code Review

This pull request introduces a smart caching strategy for the Docker-based linter, using named volumes for faster local builds and bind mounts for CI environments to leverage existing caching mechanisms. The implementation is clean and well-commented. My review includes one suggestion to add a make target for cleaning up the newly introduced Docker named volumes, which would help developers manage disk space and ensure a clean build environment when needed.

[gemini-code-assist]

With the introduction of named Docker volumes for local development, it would be beneficial to also add a make target to clean them up. These volumes will persist on the user's machine and can grow in size over time. A developer might want to clear them to start from a clean slate or to free up disk space.

You could add a new target like this:

.PHONY: clean-docker-volumes
clean-docker-volumes:
	@$(call print, "Removing Docker cache volumes.")
	docker volume rm lnd-go-build-cache lnd-go-mod-cache lnd-go-lint-cache || true

This would improve the developer experience by providing a managed way to handle these new resources.

[ziggie1984]

I think adding this cleanup also makes sense.

[Roasbeef]

Will addd

[ziggie1984]

LGTM, my mac is generally super fast so I did not immediately saw the improvement but also not deterioration therefore if it works for other people let's use named volumes.