crowdsecurity/crowdsec · error

unknown cache strategy '%s'

Error message

unknown cache strategy '%s'

What it means

RegexpCacheInit configures a regexp cache (rafthrift/cache LRU/LFU/ARC builder) from a cache config. This error is thrown when the config's cache strategy string is not one of the recognized strategies, so no cache can be built.

Source

Thrown at pkg/exprhelpers/helpers.go:177

		size = *cacheCfg.Size
	}

	gc := gcache.New(size)

	strategy := "LRU"
	if cacheCfg.Strategy != "" {
		strategy = cacheCfg.Strategy
	}

	switch strategy {
	case "LRU":
		gc = gc.LRU()
	case "LFU":
		gc = gc.LFU()
	case "ARC":
		gc = gc.ARC()
	default:
		return fmt.Errorf("unknown cache strategy '%s'", strategy)
	}

	if cacheCfg.TTL != nil {
		gc.Expiration(*cacheCfg.TTL)
	}

	cache := gc.Build()
	dataFileRegexCache[filename] = cache

	return nil
}

// UpdateCacheMetrics is called directly by the prom handler
func UpdateRegexpCacheMetrics() {
	metrics.RegexpCacheMetrics.Reset()

	for name := range dataFileRegexCache {
		metrics.RegexpCacheMetrics.With(prometheus.Labels{"name": name}).Set(float64(dataFileRegexCache[name].Len(true)))

View on GitHub (pinned to 909b515798)

Solutions

1. Set the cache strategy to exactly "LRU", "LFU", or "ARC" (uppercase) in the config.
2. Check for casing errors — the switch is case-sensitive, so "lru" fails.
3. Consult the crowdsec docs for the supported strategy list rather than the underlying cache library's docs.
4. Remove the strategy key to fall back to the default case if one exists in the surrounding code.

Example fix

// before (config)
cache: { strategy: "lru", size: 100 }
// after
cache: { strategy: "LRU", size: 100 }

switch strategy {
case "", "LRU", "LFU", "ARC":
	// ok
default:
	return fmt.Errorf("unsupported cache strategy %q", strategy)
}

When it happens

Trigger: Calling RegexpCacheInit with a cache config whose strategy field is e.g. "lru" (lowercase), "fifo", "none", or any misspelling — the switch only matches "LRU", "LFU", "ARC" (and the empty/default case above it).

Common situations: Typos or wrong casing in config YAML for regexp cache settings; copying cache config from another project with different strategy names; enabling a strategy the embedded cache library doesn't support.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• path must start with /
• invalid auth_type: must be one of basic_auth, headers, mtls
• on_challenge hooks are only valid in-band, not under outofba
• empty cti key
• no listen_uri or listen_socket specified

AI-assisted analysis of crowdsecurity/crowdsec@909b515798 (2026-09-06). Data as JSON: /api/errors/d37ef9302d88ab36. Report an issue: GitHub.