structlog
A lightweight structured logging tool for Node.js without any dependencies.
Example
By default this tool will generate logs like the following:
2022-03-09T19:57:48.962Z [error] i'm an error [/structlog/foo.js:5] thread=MAIN logId=017f705b-4200-0002-1101-720541fa117c
2022-03-09T19:57:48.963Z [warn] i'm a warning [/structlog/foo.js:6] thread=MAIN logId=017f705b-4200-0000-e4a6-f1df2ca4f248
However, you can configure both the log and timestamp formats.
Usage
To use this logging tool, all you need to do is install it:
yarn add structlog
And use it like so:
import { logger } from 'structlog'
logger.error('error!')
Importing logger will give you a ready-made instance of StructuredLogger with the default config, so you don't need to instantiate a new logger instance each time or pass down references to an instance.
However, you can configure options by instantiating StructuredLogger yourself, like so:
import { StructuredLogger } from 'structlog'
const logger = new StructuredLogger({ timestampFormat: 'unix' })
Options
You can configure the following options by passing them in an object as a parameter when creating StructuredLogger :
| Option | Default value | Accepted values | Description |
|---|---|---|---|
timestampFormat |
'iso' |
'iso' , 'gmt', 'unix', 'timestring' ,'localestring' |
Timestamp format to use. |
logFormat |
'{timestamp} [{type}] {message} [{path}] {tags}' |
Any string |
Log format to use {} to define variables. Accepted variables: timestamp, type, message, path, tags. |
pathFormat |
'{filePath}:{lineNumber}' |
Any string |
Format to use for the path component of the log. Use {} to define variables. Accepted variables: filePath, lineNumber, functionName, methodName, typeName. |
useColors |
false |
true, false |
Whether logs should be printed with colors according to the type (e.g. error = red). |
useThreadTagsExtension |
false |
true, false |
An extension that automatically adds a thread tag to the log specifying what thread the log happened in. |
useLogIdExtension |
false |
true, false |
An extension that automatically adds a logId tag to the log, with a unique ID as its value. |
pathStackDepth |
0 |
Any number |
(Advanced) Level of depth to determine the path portion of the log from. For example, if you write a wrapper over the logger, set this to 1 so that the path will reflect the code that called your wrapper, rather than the wrapper itself. |
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