LogOptions

The options accepted by createLogger.

type LogOptions = {
	/**
	 * The name of the logger. Adds a name field to every JSON line logged.
	 */
	name: string
	/**
	 * The minimum level to log.
	 * Typically, debug and trace logs are only valid for development, and not needed in production.
	 */
	level: Level
}

Import

import type { Level, LogOptions } from '@tevm/logger'

Properties

`name`

Type: string
Required

Added as a name field to every record. This is the field you filter on to isolate one component's logs. Tevm's own components use TevmClient (the node) and @tevm/common (chain configuration); use something similarly specific for your own.

`level`

Type: Level
Required

The minimum severity to emit. Records below it are dropped cheaply.

Level

type Level = 'fatal' | 'error' | 'warn' | 'info' | 'debug' | 'trace'

Standard logging levels from least to most verbose:

Level	Numeric	Meaning
`fatal`	60	Critical errors that cause the application to crash.
`error`	50	Error conditions that might still allow it to continue.
`warn`	40	Warning conditions that should be addressed.
`info`	30	Informational messages highlighting normal progress.
`debug`	20	Detailed information for debugging purposes.
`trace`	10	Extremely detailed information, including function entry/exit.

This is also the type of createTevmNode's loggingLevel option — see Using the logger with Tevm Node.

Example

Building options from configuration, with validation:

options.ts

import { createLogger, type Level, type LogOptions } from '@tevm/logger'
 
const LEVELS = ['fatal', 'error', 'warn', 'info', 'debug', 'trace'] as const
 
/**
 * Builds LogOptions from environment variables.
 * @throws {Error} If LOG_LEVEL is set to something that is not a valid level.
 */
export const optionsFromEnv = (): LogOptions => {
	const level = process.env['LOG_LEVEL'] ?? 'info'
	if (!(LEVELS as readonly string[]).includes(level)) {
		throw new Error(`Invalid LOG_LEVEL ${JSON.stringify(level)}. Expected one of: ${LEVELS.join(', ')}`)
	}
	return {
		name: process.env['SERVICE_NAME'] ?? 'tevm-app',
		level: level as Level,
	}
}
 
const logger = createLogger(optionsFromEnv())
logger.info({ level: logger.level }, 'logger configured')

Source

src/LogOptions.ts

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