pino-zen

Colored log formatter for Pino JSON logs.

Install

npm install pino-zen

Usage

Pino Transport

Use pino-zen directly as a Pino transport for colored console output alongside other targets:

import pino from "pino";

const level = process.env.LOG_LEVEL
if (!["debug", "info", "warn", "error", "trace"].includes(level)) {
  throw new Error(`Invalid log level: ${level}`);
}

const logger = pino({
  level,
  transport: {
    targets: [
      { target: "pino/file", level, options: { destination: "app.log", append: false } },
      { target: "pino-zen", level, options: {} },
    ],
  },
  formatters: {
    bindings() {
      return {}; // Return empty object to exclude pid and hostname
    },
  },
});

Module Mode

Pino Zen includes a "Module Mode" that prepends a color-coded and right-aligned module name to your logs. This is especially useful for microservices or mono-repos where you want to distinguish logs from different components at a glance.

Performance & Alignment

Module names are automatically tracked, and the prefix is right-aligned based on the longest module name encountered during the process lifecycle.

const logger = pino({
  transport: {
      target: "pino-zen",
      options: { module: "module" },
  }
});

logger.info({ module: "api" }, "request processed");
logger.info({ module: "auth" }, "user verified");

Output:

 [api]  INFO:request processed
[auth]  INFO:user verified

CLI Pipe

Pipe any NDJSON log output through the pino-zen CLI:

node app.js | pino-zen

CLI Options

| Flag | Short | Description | Example | |------|-------|-------------|---------| | --module | -m | Use a field as the module prefix | pino-zen -m module |

Example usage:

node app.js | pino-zen -m service