log-file-write

log-file-write is a Node.js logger focused on file-based logs with timezone support, optional Slack alerts, retention cleanup, and a simple developer API.

Requirements

• Node.js >= 20

Installation

npm install log-file-write

Quick Start

import { SetUserOptions, Info, Error } from "log-file-write";

SetUserOptions({
  folderPath: "./logs",
  dateBasedFileNaming: true,
  logLevel: "debug",
  onlyFileLogging: true
});

await Info("Application started", "api", "bootstrap");
await Error("Database timeout", "api", "getUsers", { retry: 1 }, "database");

Modern API (recommended)

import { SetUserOptions, createLogger } from "log-file-write";

SetUserOptions({
  folderPath: "./logs",
  fileName: "application",
  dateBasedFileNaming: false,
  onlyFileLogging: true
});

const userLogger = createLogger({ serviceName: "user-service", methodName: "createUser" });
await userLogger.info("Creating user", { userId: "u-1001" });
await userLogger.error("User creation failed", { code: "DB_TIMEOUT" }, "database");

Slack Webhook Support

1. Create an incoming webhook in your Slack workspace.
2. Store the webhook URL in an environment variable.
3. Pass slackWebhookUrl via SetUserOptions.

import { SetUserOptions, Error } from "log-file-write";

SetUserOptions({
  folderPath: "./logs",
  onlyFileLogging: true,
  slackWebhookUrl: process.env.SLACK_WEBHOOK_URL
});

await Error("Database timeout", "billing-service", "createInvoice", { retry: 1 }, "database");

Notes:

• Slack is optional; file logging always works without it.
• If webhook delivery fails, the library logs the error and continues writing to file.
• Supported errorType values for Slack text customization: database, network, server, client, other.

API

• SetUserOptions(options) sets runtime options and validates defaults.
• GetUserOptions() returns the resolved options.
• createLogger(context) creates scoped logger helpers.
• Debug/Trace/Info/Warn/Error/Fatal/Success/Other/Log are async logging methods.

All methods support:

1. Legacy positional arguments: Info(message, serviceName?, methodName?, errorObj?, errorType?, callback?)
2. Object payload: Info({ message, serviceName, methodName, errorObj, errorType }, callback?)

Security Notes

• Log fields are sanitized to reduce log-injection risks from multiline input.
• Slack webhook failures are isolated and do not break local file logging.
• Invalid timezone/log-level options are normalized to safe defaults.

Available Options

type TDefaultOptions = {
  timeZone: string;
  folderPath: string;
  dateBasedFileNaming: boolean;
  fileName: string;
  fileNamePrefix: string;
  fileNameSuffix: string;
  fileNameExtension: string;
  dateFormat: string;
  timeFormat: string;
  logLevel: "debug" | "prod" | "prod-trace";
  onlyFileLogging: boolean;
  slackWebhookUrl?: string;
  logsDeletePeriodInDays?: number;
};

Development

npm install
npm run lint
npm run build
npm test

Timezone Reference

• IANA timezone list