Redis

dotnet add package ActionCache.Redis

builder.Services.AddActionCache(options =>
{
    options.UseRedisCache(redis => redis.Configuration = "localhost:6379");
});

The delegate configures RedisCacheOptions, so a ConfigurationOptions instance, credentials or TLS settings all go here. A shorthand overload takes the configuration string directly:

options.UseRedisCache("localhost:6379");

Keyspace notifications

The Redis backend keeps a sorted-set index per namespace, which is what makes namespace eviction and refresh possible without scanning. Entries that expire on their own have to be removed from that index, and the backend learns about them from Redis key-expired events.

Enable the Ex flags for that cleanup to run:

redis-cli config set notify-keyspace-events Ex

or in redis.conf:

notify-keyspace-events Ex

The listener targets the database in your connection string.

Without Ex nothing breaks. The index self-heals lazily when it is next read — cleanup is deferred rather than lost. Enabling the flags keeps the index tight instead.

If the subscription cannot be established at startup — Redis not up yet, for instance — the host does not fail. The failure is logged at Warning and retried with exponential backoff until it succeeds.

Locking

None needed for cache operations: they are atomic through Lua scripts.

Redis does supply a distributed lock, which is what UseDistributedSingleFlight() uses. When both Redis and SQL Server are registered, Redis is preferred.

Connection

The connection is established lazily, so an application starts even when Redis is not reachable yet. Until it is, cache operations degrade under the usual resilience rules.

Memory SQL Server