> ## Documentation Index
> Fetch the complete documentation index at: https://healthzkit.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Checks and adapters

> Configure Healthzkit checks and adapters—probe types, per-check timeouts, degraded and fail rollup rules, metadata hooks, and custom HealthAdapter implementations.

## `CheckConfig`

Each check is a `CheckConfig` entry in the `checks` array on the root config:

| Field            | Purpose                                                                                                                                                                                |
| ---------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **`name`**       | Key in the response `checks` object.                                                                                                                                                   |
| **`type`**       | One or both of `"liveness"` and `"readiness"`. Only checks that include the probe type run for that probe. If none match, the response is still **200** with an empty `checks` object. |
| **`adapter`**    | Must implement `HealthAdapter`: `check(): Promise<AdapterResult>`.                                                                                                                     |
| **`timeout`**    | Per-check timeout in milliseconds. Default **5000**, unless overridden by `defaults.timeout`.                                                                                          |
| **`schedule`**   | Optional `{ intervalMs }`. When `kit.start()` has been called, the adapter runs on that interval and results are **cached** (see [Scheduling](/guide/scheduling)).                     |
| **`onFail`**     | Optional `httpStatus`, `treatAs` (for example map `"fail"` to `"degraded"` for rollup and body while adjusting HTTP rules).                                                            |
| **`onDegraded`** | Present on the type; degraded HTTP status for the overall response is controlled via **`defaults.onDegraded`** (see [Responses and HTTP](/guide/responses-and-http)).                  |

## `AdapterResult`

Each `adapter.check()` resolves to:

* **`status`**: `"ok" | "degraded" | "fail"`.
* **`error`**: Optional `Error` or string (included in the serialized check unless `output.exposeError` is `false`).
* **`metadata`**: Optional object merged into the check result.

Thrown errors from `adapter.check()` are treated as **`fail`**, with the error message captured when `exposeError` is true.

## Official adapters

This monorepo publishes optional packages that return a `HealthAdapter` for common infrastructure: **queues**, **databases**, **storage**, **search**, and **HTTP endpoints**. For anything else, use a custom `adapter.check()` implementation.

### Queues

* [RabbitMQ](/adapter/rabbitmq) — `@healthzkit/rabbitmq`
* [Kafka](/adapter/kafka) — `@healthzkit/kafka`

### Databases

* [Redis](/adapter/redis) — `@healthzkit/redis`
* [Valkey](/adapter/valkey) — `@healthzkit/valkey`
* [Postgres](/adapter/postgres) — `@healthzkit/postgres`
* [CockroachDB](/adapter/cockroach) — `@healthzkit/cockroach`
* [MySQL](/adapter/mysql) — `@healthzkit/mysql`
* [MongoDB](/adapter/mongo) — `@healthzkit/mongo`
* [SQLite](/adapter/sqlite) — `@healthzkit/sqlite`
* [DynamoDB](/adapter/dynamo) — `@healthzkit/dynamo`
* [Drizzle ORM](/adapter/drizzle) — `@healthzkit/drizzle`
* [Prisma](/adapter/prisma) — `@healthzkit/prisma`

### Storage

* [S3](/adapter/s3) — `@healthzkit/s3`
* [MinIO](/adapter/minio) — `@healthzkit/minio`

### Search

* [Elasticsearch](/adapter/elasticsearch) — `@healthzkit/elasticsearch`

### HTTP

* [HTTP endpoints](/adapter/http) — `@healthzkit/http`