# Engines

> For the complete documentation index, see [llms.txt](https://effectkit.dev/llms.txt).

Declare which server engine you run with RedisProfiles, and what each profile enforces.

Source: https://effectkit.dev/docs/redis/servers/engines

A **profile** is a static description of a deployment. You pass one to a layer as `profile`, and the client applies its rules before it sends anything. Profiles never ask the server what it is.

**Example** (Declaring a Valkey Engine)

```ts twoslash
import { RedisProfiles } from "@effect-kit/redis";
import { RedisNode } from "@effect-kit/redis/node";

export const RedisLive = RedisNode.layer({
  url: "redis://localhost:6379",
  profile: RedisProfiles.valkey({ modules: ["json"] }),
});
```

Profiles are optional. Without one, the client sends every command and the server decides.

## Engine profiles [#engine-profiles]

| Profile                   | Accepted `routing`                        |
| ------------------------- | ----------------------------------------- |
| `RedisProfiles.redis`     | `"standalone"`, `"cluster"`, `"sentinel"` |
| `RedisProfiles.valkey`    | `"standalone"`, `"cluster"`, `"sentinel"` |
| `RedisProfiles.dragonfly` | `"standalone"`                            |
| `RedisProfiles.keydb`     | `"standalone"`                            |
| `RedisProfiles.redict`    | `"standalone"`                            |
| `RedisProfiles.garnet`    | `"standalone"`                            |
| `RedisProfiles.kvrocks`   | `"standalone"`                            |

An engine profile leaves TLS and authentication optional, allows any database, and restricts no command. Its checks are about how you connect:

- A profile whose `routing` does not match the layer fails with `ProfileError` and `reason: "routing"`. A standalone profile does not work with `layerCluster`.
- `modules` lists the modules your server really has. A command from a module that is not in the list fails with `ProfileError` and `reason: "module"` before it is sent. Without `modules`, the server decides.

All `ProfileError` failures have `delivery: "unsent"`.

## Engine-specific rules [#engine-specific-rules]

The only command rule in an engine profile is for Garnet. The Garnet profile rejects `ZSCAN` with `NOSCORES`, because Garnet `v2.2.4` ignores the flag, and typed replies could then not tell scores from members. The command fails with `ProfileError` and `reason: "restricted-command"`.

Everything else an engine does not implement comes back from the server as a `ServerError`.

**Example** (Rejecting a Module Command Before Sending)

```ts twoslash
import { Effect } from "effect";
import { Redis, RedisProfiles } from "@effect-kit/redis";
import { RedisNode } from "@effect-kit/redis/node";

const RedisLive = RedisNode.layer({
  url: "redis://localhost:6379",
  profile: RedisProfiles.redis({ modules: ["json"] }),
});

export const program = Effect.gen(function* () {
  const redis = yield* Redis;
  return yield* redis.ftList();
}).pipe(
  Effect.catchTag("ProfileError", (error) =>
    error.reason === "module" ? Effect.succeed([]) : Effect.fail(error),
  ),
  Effect.provide(RedisLive),
);
```

## How engines are tested [#how-engines-are-tested]

Each engine runs the package's conformance cases once, on the version listed in [Compatibility](/docs/redis/servers). The cases cover strings, keys, collections, ordered sets, sessions, events, modules and administration, over RESP2 and RESP3, on Node.js and Bun. Garnet also runs a case with its Lua support enabled.

Dragonfly, KeyDB, Redict, Garnet and Kvrocks run with no modules. Do not expect JSON or Search on them.