lago-javascript-client/esm/logging_rate_limit_observer.js

Lago JavaScript API Client

import { rateLimitUsagePct } from "./rate_limit_headers.js";
/**
 * Default usage thresholds (80%, 90%, 95%) at which the observer emits a log.
 */
export const DEFAULT_RATE_LIMIT_THRESHOLDS = [
    0.8,
    0.9,
    0.95,
];
/**
 * Returns a ready-to-use `onRateLimitInfo` callback that logs a warning each
 * time rate limit usage crosses one of the configured thresholds.
 *
 * Example:
 *
 * ```ts
 * import { Client } from "@getlago/lago-javascript-client";
 * import { loggingRateLimitObserver } from "@getlago/lago-javascript-client";
 *
 * const client = Client(apiKey, {
 *   rateLimitRetry: { onRateLimitInfo: loggingRateLimitObserver() },
 * });
 * ```
 */
export function loggingRateLimitObserver(options = {}) {
    const thresholds = [...(options.thresholds ?? DEFAULT_RATE_LIMIT_THRESHOLDS)]
        .sort((a, b) => b - a); // descending
    // deno-lint-ignore no-console
    const log = options.log ?? ((m) => console.warn(m));
    return function observe(info) {
        const pct = rateLimitUsagePct(info);
        if (pct === null)
            return;
        for (const threshold of thresholds) {
            if (pct >= threshold) {
                log(`Lago rate limit at ${(pct * 100).toFixed(0)}% (limit=${info.limit}, ` +
                    `remaining=${info.remaining}, reset=${info.reset}s, ` +
                    `${info.method} ${info.url})`);
                return;
            }
        }
    };
}