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

# Probe: http_check

> Check HTTP/HTTPS endpoints with status, body, and JSONPath assertions

## Description

The `http_check` probe sends an HTTP request to an endpoint and validates the response. Supports assertions on status code, body content, and JSONPath. This is an active check — emits metrics and a check result with latency.

## Config fields

| Field                  | Type                | Required | Default    | Description                                                            |
| ---------------------- | ------------------- | -------- | ---------- | ---------------------------------------------------------------------- |
| `type`                 | `string`            | Yes      | —          | Must be `"http_check"`                                                 |
| `url`                  | `string`            | Yes      | —          | Full URL to check (including scheme)                                   |
| `method`               | `string`            | No       | `"GET"`    | HTTP method                                                            |
| `headers`              | `map[string]string` | No       | —          | Request headers                                                        |
| `bodyTemplate`         | `string`            | No       | —          | Request body (for POST/PUT)                                            |
| `expectedStatus`       | `int[]`             | No       | any \< 400 | Acceptable status codes. Empty = any status \< 400 passes              |
| `expectedBodyContains` | `string`            | No       | —          | String that must appear in the response body                           |
| `expectedJsonPath`     | `string`            | No       | —          | JSONPath expression to check (e.g. `$.status`)                         |
| `expectedJsonValue`    | `any`               | No       | —          | Expected value at the JSONPath. If omitted, only checks path existence |

## Metrics

| Metric                      | Type   | Unit | Description    |
| --------------------------- | ------ | ---- | -------------- |
| `vms.http_check.status`     | status | —    | `up` or `down` |
| `vms.http_check.latency_ms` | gauge  | ms   | Response time  |

## Example config

```json theme={null}
{
  "type": "http_check",
  "method": "GET",
  "url": "https://app.verolabs.co/health",
  "expectedStatus": [200]
}
```

**JSONPath assertion:**

```json theme={null}
{
  "type": "http_check",
  "method": "GET",
  "url": "https://api.verolabs.co/status",
  "headers": { "Authorization": "Bearer token123" },
  "expectedJsonPath": "$.status",
  "expectedJsonValue": "healthy"
}
```

## Notes

* Assertions are evaluated **in order**: status code → body contains → JSONPath.
* Response body is read up to **1 MiB**.
* A transport failure (connection refused, timeout) is a normal `down` result, not an agent error.