loglayer
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A modern logging library with a fluent API for specifying log messages, metadata and errors
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# loglayer
[](https://www.npmjs.com/package/loglayer)
[](http://www.typescriptlang.org/)
`loglayer` is a unified Typescript logger that routes logs to various logging libraries, cloud providers, files, and OpenTelemetry while providing a fluent API for specifying log messages, metadata and errors.
- For full documentation, read the [docs](https://loglayer.dev).
```javascript
// Example using the Pino logging library with LogLayer
// You can also start out with a console logger and swap to another later!
import { LogLayer } from 'loglayer';
import { pino } from 'pino';
import { PinoTransport } from '@loglayer/transport-pino';
import { redactionPlugin } from '@loglayer/plugin-redaction';
const log = new LogLayer({
// Multiple loggers can also be used at the same time.
transport: new PinoTransport({
logger: pino()
}),
// Plugins modify log data before it's shipped to your logging library.
plugins: [
redactionPlugin({
paths: ['password'],
censor: '[REDACTED]',
}),
],
// Put context data in a specific field (default is flattened)
contextFieldName: 'context',
// Put metadata in a specific field (default is flattened)
metadataFieldName: 'metadata',
})
// persisted data that is always included in logs
log.withContext({
path: "/",
reqId: "1234"
})
log.withPrefix("[my-app]")
.withError(new Error('test'))
// data that is included for this log entry only
.withMetadata({ some: 'data', password: 'my-pass' })
// Non-object data only (numbers, booleans, and strings only)
// this can be omitted to just log an object / error
// by using .errorOnly() / .metadataOnly() instead of withError() / withMetadata()
.info('my message')
```
```json5
{
"level": 30,
"time": 1735857465669,
"msg": "[my-app] my message",
"context": {
"path": "/",
"reqId": "1234",
},
"metadata": {
"password": "[REDACTED]",
"some": "data",
},
"err":{
"type": "Error",
"message": "test",
"stack": "Error: test\n ..."
}
}
```
With the [Pretty Terminal Transport](https://loglayer.dev/transports/pretty-terminal):
## Installation
Install the core package:
```bash
npm i loglayer
```
## Quick Start
```typescript
import { LogLayer, ConsoleTransport } from 'loglayer'
const log = new LogLayer({
transport: new ConsoleTransport({
logger: console,
}),
})
log
.withMetadata({ some: 'data'})
.withError(new Error('test'))
.info('my message')
```
- See the [LogLayer configuration documentation](https://loglayer.dev/configuration.html) for more configuration options.
- See the [Console Transport documentation](https://loglayer.dev/transports/console.html) for more configuration options.