API monitors send HTTP requests and evaluate the response with a JavaScript function. Use them for any HTTP or HTTPS endpoint.
Configuration fields
| Field | Type | Default | Notes |
|---|
url | string | — | Required |
method | GET | POST | PUT | PATCH | DELETE | HEAD | OPTIONS | GET | |
headers | { key: string; value: string }[] | [] | Optional custom headers |
body | string | "" | Sent for non-GET/HEAD methods |
timeout | number | 10000 | Request timeout in milliseconds |
allowSelfSignedCert | boolean | false | Disables TLS certificate verification |
eval | string (JS function) | built-in default | See eval contract below |
Default eval behavior
When no custom eval is set, the monitor returns UP when:
- the HTTP status code is
429, or
- the status code is in the
2xx or 3xx range
All other status codes return DOWN.
The built-in eval function:
async function (statusCode, responseTime, responseRaw, modules) {
let statusCodeShort = Math.floor(statusCode / 100);
if (statusCode == 429 || (statusCodeShort >= 2 && statusCodeShort <= 3)) {
return {
status: 'UP',
latency: responseTime,
}
}
return {
status: 'DOWN',
latency: responseTime,
}
}
Custom eval contract
Your function receives four arguments:
| Argument | Type | Description |
|---|
statusCode | number | HTTP response status code |
responseTime | number | Measured latency in milliseconds |
responseRaw | string | Raw response body as a string |
modules | object | Available libraries — currently includes cheerio |
{ status: "UP" | "DEGRADED" | "DOWN" | "MAINTENANCE", latency: number }
If the eval function throws an error or returns an invalid shape, the monitor records DOWN for that run.
Examples
{
"type": "API",
"type_data": {
"url": "https://api.example.com/health",
"method": "GET",
"timeout": 10000
}
}
Use $VARIABLE_NAME in the URL, headers, or body to reference environment variables stored as secrets. Kener replaces them before sending the request.
Troubleshooting
- Always DOWN: verify the URL is reachable from your Kener host, check method and headers
- TLS errors: enable
allowSelfSignedCert only for trusted self-signed endpoints
- Eval errors: check that your function always returns a valid
{ status, latency } object
- Timeout: increase
timeout or investigate network latency from Kener to the target