API monitor

Monitor HTTP/HTTPS endpoints with custom methods, headers, request body, and JavaScript eval logic.

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

It must return an object with:

{ 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

Basic GET check

{
    "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