Configurable http caching middleware for Go servers.
Improve API throughput, reduce latency, and save on third-party resources.

• Eviction Policy: FIFO, LRU
• Cache Size: Based on number of entries, or memory usage
• Cache Filters: Filter on URL, method, or header fields
• TTL + Max TTL: Cache expiration and renewal
• Logger: Pass any logger package
• Metrics: Track cache hits, misses, and evictions

import (
	"log"
	"net/http"
	"os"
	"time"
	"github.com/Ztkent/replay"
	"github.com/go-chi/chi/v5"
)

func main() {
	r := chi.NewRouter()
	c := replay.NewCache(
		replay.WithMaxSize(100),
		replay.WithMaxMemory(100*1024*1024),
		replay.WithCacheFilters([]string{"URL", "Method"}),
		replay.WithCacheFailures(false),
		replay.WithEvictionPolicy("LRU"),
		replay.WithTTL(5*time.Minute),
		replay.WithMaxTTL(30*time.Minute),
		replay.WithLogger(log.New(os.Stdout, "replay: ", log.LstdFlags)),
	)

	// Apply the middleware to the entire router
	r.Use(c.Middleware)
	// Or apply it to a specific endpoint
	r.Get("/test-endpoint", c.MiddlewareFunc(testHandlerFunc()))
	http.ListenAndServe(os.Getenv("SERVER_PORT"), r)
}

The cache configured with the following options:

• WithMaxSize(maxSize int): Set the maximum number of entries in the cache.
• WithMaxMemory(maxMemory uint64): Set the maximum memory usage of the cache.
• WithEvictionPolicy(evictionPolicy string): Set the eviction policy for the cache [FIFO, LRU].
• WithEvictionTimer(evictionTimer time.Duration): Set the time between cache eviction checks.
• WithTTL(ttl time.Duration): Set the time a cache entry can live without being accessed.
• WithMaxTTL(maxTtl time.Duration): Set the maximum time a cache entry can live, including renewals.
• WithCacheFilters(cacheFilters []string): Set the cache filters to use for generating cache keys.
• WithCacheFailures(cacheFailures bool): Set whether to cache failed requests.
• WithLogger(l *log.Logger): Set the logger to use for cache logging.

You can access cache metrics to monitor cache performance:

metrics := c.Metrics()

Fields Available:

• Hits: Total number of cache hits.
• Misses: Total number of cache misses.
• Evictions: Total umber of cache evictions.
• CurrentSize: Number of entries in the cache.
• CurrentMemory: Current memory usage of the cache.