feat(export): support s3 and configurable location for helm cache

[julienduchesne]

Summary

Extend the experimental helmTemplate export cache so it can live somewhere other than the output directory — including S3 — and so callers can decide how strict cache failures should be.

• Replace --helm-cache-dir with --helm-cache-path, which accepts a local path, a file:// URL, or an s3://bucket/prefix URL. Setting it enables the cache and overrides the default <output_dir>/helm-cache.
• Add --helm-cache-on-error=warn|fail: warn logs and continues (the export still succeeds without a persisted cache), fail aborts the export.
• Abstract the cache behind a CacheLocation backend. The S3 backend lists and fetches entries into the in-memory cache on load, then puts the entries touched this run and prunes stale objects under the prefix on save.

Context

The cache load/save run once per export, single-threaded outside the rayon pool, so the S3 calls are driven by a private current-thread tokio runtime. S3 credentials and region come from the standard AWS default chain (env, profile, IMDS).

Note: like the local backend, an export that makes no helmTemplate calls prunes the whole prefix (nothing touched), so pointing --helm-cache-path at a shared S3 prefix and running a helm-free export will clear it.

Made with Cursor

[github-actions]

Benchmark Results

Benchmark	Test	vs tk	vs base
Diff	cluster_scoped	1.43x faster	39.33x slower
Diff	configmap_unchanged	0.79x faster	38.51x slower
Diff	deployment_nested_changes	0.81x faster	37.73x slower
Env List	Single Inline Directory (--json)	50.06x faster	equal
Env List	Single Inline File (--json)	48.83x faster	equal
Env List	All Environments (--json)	87.17x faster	equal
Eval	Single Static Environment	14.96x faster	1.04x slower
Eval	Inline Environment File	19.18x faster	equal
Eval	Eval Expression - Deeply Nested Path	14.11x faster	equal
Export (Full)	Single Static Environment	6.47x faster	equal
Export (Full)	Single Inline Environment	20.63x faster	equal
Export (Full)	All Environments	19.3x faster	equal
Export (Replace)	Single Static Environment	5.6x faster	equal
Export (Replace)	Single Inline Environment	21.91x faster	equal
Export (Replace)	All Environments	28.19x faster	equal
Helm Template	Full Export	1.36x faster	equal
Tool Importers Count	Single Lib Directory (Non-Recursive)	2.18x faster	equal
Tool Importers Count	Single Lib Directory (Recursive)	2.21x faster	equal
Tool Importers Count	Entire Lib Directory (Non-Recursive)	1.32x faster	equal
Tool Importers Count	Entire Lib Directory (Recursive)	1.16x faster	equal
Tool Importers	Global Lib File	3.26x faster	equal
Tool Importers	Single Env-Specific Lib File	1.67x faster	equal
Tool Importers	All Env-Specific Lib Files	5.12x faster	equal
Tool Importers	All Lib Files	5.17x faster	equal
Tool Importers	All Jsonnet Files	8.83x faster	equal
Tool Imports	Single Static Environment	3.11x faster	equal
Tool Imports	Single Inline Environment File	3.12x faster	equal
Validate Manifests	All Validations	-	equal
Validate Manifests	Manifest Tests Only	-	equal
Validate Manifests	Namespace Test Only	-	equal

Full results available in workflow artifacts.

Benchmark run on commit ec458ae95eec4f10724c55b41b91f593d067c49d