encore-go-cache

Encore Go Caching (Redis)

Instructions

Encore Go's cache is a typed wrapper around Redis. Declare a cache.Cluster once, then create Keyspace objects for each shape of data you need.

Cluster

package mycache

import "encore.dev/storage/cache"

var Cluster = cache.NewCluster("my-cache", cache.ClusterConfig{
    EvictionPolicy: cache.AllKeysLRU,
})

Eviction policies: cache.AllKeysLRU (default), cache.NoEviction, cache.AllKeysLFU, cache.AllKeysRandom, cache.VolatileLRU, cache.VolatileLFU, cache.VolatileTTL, cache.VolatileRandom.

Keyspace types

Each keyspace has a key shape (used to build the Redis key from KeyPattern) and a value type.

package mycache

import (
    "context"
    "time"
    "encore.dev/storage/cache"
)

type TokenKey struct {
    TokenID string
}

// Strings
var Tokens = cache.NewStringKeyspace[TokenKey](Cluster, cache.KeyspaceConfig{
    KeyPattern:    "token/:TokenID",
    DefaultExpiry: cache.ExpireIn(time.Hour),
})

func example(ctx context.Context) {
    _ = Tokens.Set(ctx, TokenKey{TokenID: "abc"}, "value")
    val, err := Tokens.Get(ctx, TokenKey{TokenID: "abc"}) // cache.Miss on miss
    _ = Tokens.Delete(ctx, TokenKey{TokenID: "abc"})
    _ = val
    _ = err
}

// Integers (atomic counters)
type CounterKey struct {
    UserID string
}

var Counters = cache.NewIntKeyspace[CounterKey](Cluster, cache.KeyspaceConfig{
    KeyPattern:    "requests/:UserID",
    DefaultExpiry: cache.ExpireIn(10 * time.Second),
})

func incr(ctx context.Context) {
    count, _ := Counters.Increment(ctx, CounterKey{UserID: "user123"}, 1)
    _, _ = Counters.Decrement(ctx, CounterKey{UserID: "user123"}, 1)
    _ = count
}

// Structs (JSON-encoded)
type ProfileKey struct {
    UserID string
}

type UserProfile struct {
    Name  string
    Email string
}

var Profiles = cache.NewStructKeyspace[ProfileKey, UserProfile](Cluster, cache.KeyspaceConfig{
    KeyPattern:    "profile/:UserID",
    DefaultExpiry: cache.ExpireIn(time.Hour),
})

func setProfile(ctx context.Context) {
    _ = Profiles.Set(ctx, ProfileKey{UserID: "123"}, UserProfile{
        Name: "Alice", Email: "[email protected]",
    })
}

Other keyspace types

All from encore.dev/storage/cache:

• NewFloatKeyspace — float64 values, has Increment.
• NewListKeyspace — list values, with PushLeft/PushRight/PopLeft/PopRight/GetRange.
• NewSetKeyspace — set values, with Add/Remove/Contains/Items.

Multi-field key patterns

type ResourceKey struct {
    UserID       string
    ResourcePath string
}

var ResourceRequests = cache.NewIntKeyspace[ResourceKey](Cluster, cache.KeyspaceConfig{
    KeyPattern:    "requests/:UserID/:ResourcePath",
    DefaultExpiry: cache.ExpireIn(10 * time.Second),
})

Expiry helpers

import (
    "encore.dev/storage/cache"
    "time"
)

cache.ExpireIn(time.Hour)              // relative
cache.ExpireDailyAt(2, 0, 0, time.UTC) // specific UTC time each day
cache.NeverExpire                      // no expiry
cache.KeepTTL                          // keep existing TTL when updating

Errors

import "encore.dev/storage/cache"

val, err := keyspace.Get(ctx, key)
if errors.Is(err, cache.Miss) {
    // not in cache
}

err = keyspace.SetIfNotExists(ctx, key, value)
if errors.Is(err, cache.KeyExists) {
    // already there
}

Guidelines

• Declare cache.Cluster and keyspaces as package-level variables.
• Pick the most specific keyspace type — IntKeyspace for counters gives you atomic Increment/Decrement for free.
• Get() returns cache.Miss on miss; Replace() and SetIfNotExists() return cache.Miss/cache.KeyExists on conflict.
• Local development uses an in-memory Redis with a ~100-key cap — don't load-test it.
• For durable storage, use encore-go-database (Postgres) or encore-go-bucket (object storage) instead.