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

# HTTP desired count

The **HTTP scale API (desired)** target requests a concrete replica count from your platform. Arklow clamps the request to the target's minimum and maximum.

This mode uses the shared [status endpoint and authentication contract](/resources/scale-targets/http/index).

## Write contract

Arklow sends:

```http theme={null}
PUT {endpoint}/scale/desired
Content-Type: application/json
```

```json theme={null}
{
  "desired_replicas": 3
}
```

Return a `2xx` response after your platform accepts the target size. Return `409` when a previous change is still converging; Arklow treats the write as unsettled and waits before trying another change.

The status endpoint should report `current_replicas` when available and use `settled` to show whether the requested count has converged.

## Add an HTTP desired-count target

<Steps>
  <Step title="Prepare the API">
    Implement the shared status endpoint and the desired-count write endpoint.
  </Step>

  <Step title="Open scale targets">
    Go to [**Scale Targets**](https://app.arklow.io/dashboard/scale-targets), click **New scale target**, and select **HTTP scale API (desired)**.
  </Step>

  <Step title="Enter the endpoint">
    Provide the public HTTPS base URL of the scale API.
  </Step>

  <Step title="Select authentication">
    Choose the HTTP Auth Headers credential containing the headers your API expects.
  </Step>

  <Step title="Select capacity">
    Choose the destination or shared pool served by this platform.
  </Step>

  <Step title="Set the envelope">
    Enter the minimum and maximum replica counts Arklow may request.
  </Step>

  <Step title="Save">
    Create the target and confirm that its first status observation matches your platform.
  </Step>
</Steps>