@json-express/logger-pino

High-performance, industry-standard structured logging for JSONExpress.

📦 Overview

@json-express/logger-pino is the recommended logger for production. It produces high-speed, asynchronous, JSON-structured log output that drops straight into modern observability stacks — ELK, Splunk, Datadog, CloudWatch, Loki, and friends.

It wraps Pino and implements the JSONExpress ILogger interface.

🚀 Key Features

• Structured by Default: One JSON object per line with level, time, pid, hostname, component, and msg — ready to ship to any log aggregator.
• Request Correlation: Reads the framework-wide traceId from RequestContext and stamps it onto every log line — no manual propagation needed.
• High Performance: Asynchronous file/stream transports keep logging off the request path.
• Two Output Modes: enterprise file mode (default — writes to ./logs/app.log) or 12-factor stream mode (stdout/stderr), with optional pino-pretty formatting in development.

🛠️ Configuration

All settings are JSONExpress environment variables. . and __ are interchangeable nesting separators; case is insensitive.

| Key | Default | Description | | :--- | :--- | :--- | | jex.logger | (unset — falls back to console) | Set to @json-express/logger-pino to activate. | | jex.log.level | info | Logging severity (info, debug, warn, error). | | jex.log.path | ./logs | Destination directory or file path. Set to stdout or stderr for terminal output. | | jex.log.pretty | true in development, otherwise false | Pretty terminal output via pino-pretty. Only applies to stream mode (stdout/stderr). |

🔄 Logging Modes

1. File Mode (default) — logs land in ./logs/app.log as raw JSON. Override the directory with jex.log.path=./var/server (becomes ./var/server/app.log) or pass a full file path with jex.log.path=/var/log/my-app.log. Missing directories are created on demand.
2. Stream Mode — set jex.log.path=stdout (or stderr) to pipe directly to the terminal. Combine with jex.log.pretty=true for a colorized, dev-friendly stream.

💻 Manual Usage

If you are wiring up a JSONExpress kernel without the CLI:

import { JsonExpressKernel } from '@json-express/core';
import { EnvConfigProvider } from '@json-express/config-env';
import { PinoLogger } from '@json-express/logger-pino';

const config = new EnvConfigProvider();
const logger = new PinoLogger({ configProvider: config });

const kernel = new JsonExpressKernel();
kernel.registerLogger(logger);

📜 Standardized Interface

export interface ILogger {
    info(message: string, context?: any): void;
    warn(message: string, context?: any): void;
    error(message: string, context?: any): void;
    debug(message: string, context?: any): void;
    child(context: any): ILogger;
}

See also

• example/logger-pino — runnable example showing structured output and traceId correlation
• @json-express/logger-console — the zero-dependency default logger