Configuration

Configuration interface and options for @shinijs/logger.

LoggerConfig

Main configuration interface.

interface LoggerConfig {
  level: string;
  prettyPrint: boolean;
  fileEnabled: boolean;
  filePath: string;
  fileRotationEnabled: boolean;
  fileRotationFrequency: 'daily' | 'hourly' | 'custom';
  fileRotationPattern: string;
  fileMaxFiles: number;
  fileSizeLimit: string;
}

Properties

Core Properties

Property	Type	Description
level	string	Minimum log level (trace, debug, info, warn, error, fatal)
prettyPrint	boolean	Enable pretty console output
fileEnabled	boolean	Enable file logging
filePath	string	Directory path for log files

File Rotation Properties

Property	Type	Description
fileRotationEnabled	boolean	Enable automatic log file rotation. When enabled, logs are written to timestamped files instead of a single app.log file
fileRotationFrequency	'daily' | 'hourly' | 'custom'	Rotation frequency. daily creates new files each day, hourly creates new files each hour, custom allows custom intervals
fileRotationPattern	string	Date format pattern for log file names. Uses moment.js format tokens (e.g., YYYY-MM-DD for daily, YYYY-MM-DD-HH for hourly)
fileMaxFiles	number	Maximum number of log files to retain. Older files are automatically deleted when this limit is exceeded
fileSizeLimit	string	Maximum file size before rotation (e.g., 10M for 10 megabytes, 1G for 1 gigabyte). Works in conjunction with time-based rotation

Default Values

{
  level: process.env.LOG_LEVEL || 'info',
  prettyPrint: process.env.NODE_ENV !== 'production',
  fileEnabled: process.env.LOG_FILE_ENABLED === 'true',
  filePath: process.env.LOG_FILE_PATH || './logs',
  fileRotationEnabled: fileEnabled && process.env.LOG_FILE_ROTATION_ENABLED !== 'false',
  fileRotationFrequency: process.env.LOG_FILE_ROTATION_FREQUENCY || 'daily',
  fileRotationPattern: process.env.LOG_FILE_ROTATION_PATTERN || 'YYYY-MM-DD',
  fileMaxFiles: parseInt(process.env.LOG_FILE_MAX_FILES || '7', 10),
  fileSizeLimit: process.env.LOG_FILE_SIZE_LIMIT || '10M',
}

Default Rotation Behavior

When file logging is enabled (fileEnabled: true), rotation is automatically enabled by default. To disable rotation and use a single app.log file, explicitly set LOG_FILE_ROTATION_ENABLED=false.

Environment Variables

Configuration is read from environment variables:

Core Variables

Variable	Config Property	Default	Valid Values
LOG_LEVEL	level	'info'	trace, debug, info, warn, error, fatal
LOG_PRETTY_PRINT	prettyPrint	NODE_ENV !== 'production'	true, false
LOG_FILE_ENABLED	fileEnabled	false	true, false
LOG_FILE_PATH	filePath	'./logs'	Any valid directory path

File Rotation Variables

Variable	Config Property	Default	Valid Values
LOG_FILE_ROTATION_ENABLED	fileRotationEnabled	true (when file logging enabled)	true, false
LOG_FILE_ROTATION_FREQUENCY	fileRotationFrequency	'daily'	daily, hourly, custom
LOG_FILE_ROTATION_PATTERN	fileRotationPattern	'YYYY-MM-DD'	Any moment.js date format
LOG_FILE_MAX_FILES	fileMaxFiles	7	Any positive integer
LOG_FILE_SIZE_LIMIT	fileSizeLimit	'10M'	Size string (e.g., 10M, 1G, 500K)

Accessing Configuration

Via Dependency Injection

import { Injectable, Inject } from '@nestjs/common';
import type { ConfigType } from '@nestjs/config';
import loggerConfig, { LoggerConfig } from '@shinijs/logger';

@Injectable()
export class MyService {
  constructor(
    @Inject(loggerConfig.KEY)
    private readonly config: ConfigType<typeof loggerConfig>,
  ) {
    console.log('Log level:', this.config.level);
    console.log('Pretty print:', this.config.prettyPrint);
  }
}

Type-Safe Access

import type { LoggerConfig } from '@shinijs/logger';

function validateConfig(config: LoggerConfig): boolean {
  const validLevels = ['trace', 'debug', 'info', 'warn', 'error', 'fatal'];
  return validLevels.includes(config.level);
}

Configuration Registration

The configuration is registered using @nestjs/config:

import { registerAs } from '@nestjs/config';

export default registerAs('logger', (): LoggerConfig => ({
  level: process.env.LOG_LEVEL || 'info',
  prettyPrint: process.env.NODE_ENV !== 'production',
  fileEnabled: process.env.LOG_FILE_ENABLED === 'true',
  filePath: process.env.LOG_FILE_PATH || './logs',
}));

Custom Configuration

You can override the default configuration by providing your own:

import { Module } from '@nestjs/common';
import { ConfigModule } from '@nestjs/config';
import { LoggerModule } from '@shinijs/logger';

@Module({
  imports: [
    ConfigModule.forRoot({
      load: [
        () => ({
          logger: {
            level: 'debug',
            prettyPrint: true,
            fileEnabled: true,
            filePath: './custom-logs',
            fileRotationEnabled: true,
            fileRotationFrequency: 'daily',
            fileRotationPattern: 'YYYY-MM-DD',
            fileMaxFiles: 14,
            fileSizeLimit: '20M',
          },
        }),
      ],
    }),
    LoggerModule,
  ],
})
export class AppModule {}

Validation

The configuration includes automatic validation with fallback to defaults:

Core Properties

• level must be a valid log level (trace, debug, info, warn, error, fatal)
• filePath must be a valid directory path
• prettyPrint and fileEnabled are boolean values

Rotation Properties

• fileRotationFrequency must be daily, hourly, or custom (invalid values default to daily with console warning)
• fileMaxFiles must be a valid positive integer (invalid values default to 7 with console warning)
• fileSizeLimit should use format like 10M, 1G, 500K
• fileRotationPattern should use valid moment.js date format tokens

Behavior Notes

• File logging works simultaneously with pretty printing - when both are enabled, logs are written to both the console (with pretty formatting) and to the log file
• Rotation is enabled by default when file logging is enabled - explicitly set LOG_FILE_ROTATION_ENABLED=false to use a single log file
• Invalid configuration values trigger console warnings and fall back to safe defaults

Rotation Configuration Examples

Daily Rotation (Default)

LOG_FILE_ENABLED=true
LOG_FILE_PATH=./logs
# Rotation is enabled by default
# Creates: app-2024-01-15.log, app-2024-01-16.log, etc.

Hourly Rotation

LOG_FILE_ENABLED=true
LOG_FILE_ROTATION_FREQUENCY=hourly
LOG_FILE_ROTATION_PATTERN=YYYY-MM-DD-HH
# Creates: app-2024-01-15-14.log, app-2024-01-15-15.log, etc.

Custom Retention Period

LOG_FILE_ENABLED=true
LOG_FILE_MAX_FILES=30
# Keeps 30 days of logs instead of default 7

Size-Based Rotation

LOG_FILE_ENABLED=true
LOG_FILE_SIZE_LIMIT=50M
# Rotates when file reaches 50MB

Disable Rotation

LOG_FILE_ENABLED=true
LOG_FILE_ROTATION_ENABLED=false
# Uses single app.log file (legacy behavior)

File Naming Patterns

When rotation is enabled, log files are named using the base name app plus the date pattern:

Frequency	Pattern	Example Filename
daily	YYYY-MM-DD	app-2024-01-15.log
hourly	YYYY-MM-DD-HH	app-2024-01-15-14.log
custom	User-defined	app-<pattern>.log
Disabled	N/A	app.log

See Also

• Configuration Guide - How to configure the logger
• LoggerModule - Module configuration
• File Rotation - Advanced rotation strategies and troubleshooting