Core API Reference

Complete reference for the FlareLog SDK core API.

Overview

The FlareLog SDK provides a zero-dependency observability client that ships logs, errors, and traces to FlareLog or any OTLP-compatible backend.

Key Components

• FlareLog Class — Main logger class with all logging methods
• FlareLogChild Class — Child loggers for scoped contexts
• Configuration — Full configuration options via FlareLogConfig
• Logging Methods — trace, debug, info, warn, error, fatal
• Error Handling — logError, capture, captureSync
• Transports — Console, FlareLog, and OTLP transports

Quick Example

import { flarelog } from "@flarelog/sdk";

const logger = flarelog({
  apiKey: "fl_your_api_key",
  // Everything else is auto-detected!
});

logger.info("Application started");
logger.error("Something went wrong", { error: "details" });

Auto-Detection

The flarelog() factory automatically detects:

• Environment: development, production, etc. (reads VERCEL_ENV, NODE_ENV, CF env)
• Release: from npm_package_version, VERCEL_GIT_COMMIT_SHA, CF_PAGES_COMMIT_SHA
• Server name: hostname or VERCEL_REGION
• Platform: Cloudflare Workers, Vercel, Node.js, browser — adjusts batching and flushing
• Auto-capture: console, globalErrors, rejections

Log Levels

• TRACE - Detailed debugging
• DEBUG - Development debugging
• INFO - General information
• WARN - Warning events
• ERROR - Error events
• FATAL - Critical errors

Core Methods

// Logging
logger.trace(message, metadata?)
logger.debug(message, metadata?)
logger.info(message, metadata?)
logger.warn(message, metadata?)
logger.error(message, metadata?)
logger.fatal(message, metadata?)

// Error handling
logger.logError(error, { message, metadata, source })
await logger.capture(() => riskyOperation(), { label: "Operation" })

// Context
logger.setUser({ id, email, name })
logger.setTag(key, value)
logger.addBreadcrumb({ category, message, data })

// Control
await logger.flush()
logger.destroy()