VoltLog

Structured logger for real-time infrastructure — zero dependencies, type-safe, OCPP-aware

VoltLog is a modern, lightweight, and type-safe structured logger designed for high-throughput, real-time systems like IoT platforms, WebSocket servers (OCPP), and microservices.

📚 Full Documentation

For detailed guides, API reference, and advanced usage:

👉 https://ocpp-ws-io.rohittiwari.me/docs/voltlog-io

📦 Installation

npm install voltlog-io

🚀 Quick Start

import { createLogger, prettyTransport, consoleTransport } from "voltlog-io";

// Development — pretty colored output
const logger = createLogger({
  level: "DEBUG",
  transports: [prettyTransport()],
});

// Production — structured JSON
const logger = createLogger({
  level: "INFO",
  transports: [consoleTransport()],
});

logger.info("Server started", { port: 3000, env: "production" });
logger.error("Connection failed", new Error("ETIMEDOUT"));

📖 Features

Core Logging

// All log levels
logger.trace("Entering function");
logger.debug("Parsed payload", { bytes: 1024 });
logger.info("User authenticated", { userId: "u-42" });
logger.warn("Rate limit approaching", { rate: 95 });
logger.error("Query failed", { query: "SELECT *" }, new Error("timeout"));
logger.fatal("Unrecoverable", new Error("OOM"));

// Runtime level control
logger.setLevel("WARN"); // change at runtime
logger.getLevel(); // → "WARN"
logger.isLevelEnabled("DEBUG"); // → false (useful to guard expensive computation)

// Timer helper — auto-logs duration
const timer = logger.startTimer();
await doExpensiveWork();
timer.done("Work completed", { items: 100 });
// → INFO Work completed { durationMs: 342, items: 100 }

Child Loggers

const cpLogger = logger.child({ chargePointId: "CP-101" });
cpLogger.info("Connected");
// → context: { chargePointId: "CP-101" }

const sessionLogger = cpLogger.child({ sessionId: "sess-xyz" });
sessionLogger.info("Charging started");
// → context: { chargePointId: "CP-101", sessionId: "sess-xyz" }

Error Cause Chain (ES2022)

const rootCause = new Error("ECONNREFUSED 10.0.0.5:5432");
const dbError = new Error("DB connection failed", { cause: rootCause });
const appError = new Error("Request failed", { cause: dbError });

logger.error("Handler crashed", appError);
// → error.cause.cause.message = "ECONNREFUSED 10.0.0.5:5432" ← root cause preserved!

Custom ID Generator

// Default: crypto.randomUUID() (fast, native)
const logger = createLogger({ transports: [...] });

// Custom generator
const logger = createLogger({
  idGenerator: () => `log-${Date.now()}-${Math.random().toString(36).slice(2)}`,
  transports: [...],
});

// Disable for max performance
const logger = createLogger({ idGenerator: false, transports: [...] });

---

🔌 Transports (14 Built-in)

Console & Pretty

import { consoleTransport, prettyTransport } from "voltlog-io";

consoleTransport(); // JSON to stdout
prettyTransport({ colors: true, timestamps: true }); // colored dev output

File (Daily + Size Rotation)

import { fileTransport } from "voltlog-io";

fileTransport({
  dir: "./logs",
  filename: "app-%DATE%.log", // daily rotation
  maxSize: 10_000_000, // 10MB size rotation
});
// → logs/app-2026-02-28.log → logs/app-2026-02-28.1.log (at 10MB)

Ring Buffer (In-Memory Diagnostics)

import { ringBufferTransport } from "voltlog-io";

const ring = ringBufferTransport({ maxSize: 500 });

// Query buffered logs
ring.getEntries({ level: "ERROR" });
ring.getEntries({ since: Date.now() - 300_000, limit: 20 });
ring.clear();

Webhook (with Batching & Retry)

import { webhookTransport, batchTransport } from "voltlog-io";

batchTransport(
  webhookTransport({
    url: "https://api.example.com/logs",
    headers: { Authorization: "Bearer token" },
    retry: true,
    maxRetries: 3,
  }),
  { batchSize: 50, flushIntervalMs: 5000 },
);

OpenTelemetry (SigNoz, Jaeger, Grafana)

import { otelTransport, otelTraceMiddleware } from "voltlog-io";

const logger = createLogger({
  middleware: [otelTraceMiddleware()], // auto-picks traceId/spanId
  transports: [
    otelTransport({
      endpoint: "https://ingest.signoz.io",
      headers: { "signoz-access-token": "YOUR_TOKEN" },
      serviceName: "my-app",
      resource: { "deployment.environment": "production" },
    }),
  ],
});
// Every log auto-includes traceId + spanId from active OTel spans

Loki (Grafana)

import { lokiTransport } from "voltlog-io";

lokiTransport({
  host: "http://loki:3100",
  labels: { app: "my-service", env: "prod" },
  dynamicLabels: (entry) => ({ level: entry.levelName }),
  includeMetadata: true, // context, error, correlationId
  retry: true,
  maxRetries: 3,
});

Other Transports

import {
  datadogTransport, // Datadog Logs API
  sentryTransport, // Sentry (errors + breadcrumbs)
  slackTransport, // Slack webhook
  discordTransport, // Discord webhook
  redisTransport, // Redis Streams
  jsonStreamTransport, // Node.js WritableStream
  browserJsonStreamTransport, // Browser WritableStream
} from "voltlog-io";

---

🧩 Middleware (13 Built-in)

Redaction

import { redactionMiddleware } from "voltlog-io";

redactionMiddleware({
  paths: ["password", "idToken", "authorization"],
  deep: true, // search nested objects
  replacement: "[REDACTED]",
});

AsyncLocalStorage Context

import { asyncContextMiddleware } from "voltlog-io";

const asyncCtx = asyncContextMiddleware();

const logger = createLogger({
  middleware: [asyncCtx.middleware],
  transports: [prettyTransport()],
});

// Set context once — propagates across all async boundaries
app.use((req, res, next) => {
  asyncCtx.runInContext({ requestId: req.id, userId: req.user?.id }, next);
});

// Anywhere downstream — no child() needed
logger.info("Processing order");
// → auto-includes { requestId, userId }

Sampling & Rate Limiting

import { samplingMiddleware } from "voltlog-io";

samplingMiddleware({
  maxPerWindow: 10, // max 10 logs per window
  windowMs: 60_000, // per minute
  priorityLevel: 40, // WARN+ always passes
});

Other Middleware

import {
  correlationIdMiddleware, // auto-generate/propagate correlation IDs
  alertMiddleware, // trigger alerts on error spikes
  deduplicationMiddleware, // suppress repeated logs
  heapUsageMiddleware, // attach memory stats
  ipMiddleware, // extract client IP
  userAgentMiddleware, // extract User-Agent
  levelOverrideMiddleware, // dynamic level via headers
  ocppMiddleware, // OCPP protocol enrichment
  otelTraceMiddleware, // OpenTelemetry trace context
  createHttpLogger, // HTTP request/response logging
} from "voltlog-io";

---

⚡ Performance

// Max performance mode — zero overhead for filtered logs
const logger = createLogger({
  level: "WARN",
  idGenerator: false, // no ID generation
  transports: [consoleTransport()],
});

// These cost ~0.02μs each (100x faster than Pino for filtered logs)
logger.trace("free");
logger.debug("free");
logger.info("free");

// Only these execute
logger.warn("logged");
logger.error("logged");

🛡️ Graceful Shutdown

process.on("SIGTERM", async () => {
  await logger.flush(); // ensure all buffered logs are sent
  await logger.close(); // release resources (file handles, connections)
  process.exit(0);
});

🤝 Contributing

Contributions are welcome! Please see our Contributing Guide.

License

MIT © Rohit Tiwari