# Logger

_Path: en/lua/system/logger_

## Table of Contents

- Logging

## Content

# Logging

<secondary-label ref="function"/>
<secondary-label ref="process"/>
<secondary-label ref="workflow"/>
<secondary-label ref="io"/>

Structured logging with debug, info, warn, and error levels.



## Loading


```lua
local logger = require("logger")
```



### Debug


```lua
logger:debug("message", {key = "value"})
```

| Parameter | Type | Description |
|-----------|------|-------------|
| `message` | string | Log message |
| `fields` | table? | Contextual key-value pairs |



### Info


```lua
logger:info("message", {key = "value"})
```

| Parameter | Type | Description |
|-----------|------|-------------|
| `message` | string | Log message |
| `fields` | table? | Contextual key-value pairs |



### Warn


```lua
logger:warn("message", {key = "value"})
```

| Parameter | Type | Description |
|-----------|------|-------------|
| `message` | string | Log message |
| `fields` | table? | Contextual key-value pairs |



### Error


```lua
logger:error("message", {key = "value"})
```

| Parameter | Type | Description |
|-----------|------|-------------|
| `message` | string | Log message |
| `fields` | table? | Contextual key-value pairs |



### With Fields


Create a child logger with persistent fields.

```lua
local child = logger:with({request_id = id})
child:info("message")
```

| Parameter | Type | Description |
|-----------|------|-------------|
| `fields` | table | Fields to attach to all logs |

**Returns:** `Logger`



### Named Logger


Create a named child logger.

```lua
local named = logger:named("auth")
named:info("message")
```

| Parameter | Type | Description |
|-----------|------|-------------|
| `name` | string | Logger name |

**Returns:** `Logger`



## Errors


| Condition | Kind | Retryable |
|-----------|------|-----------|
| Empty name string | `errors.INVALID` | no |

See [Error Handling](lua/core/errors.md) for working with errors.



## Navigation

Previous: Environment (lua/system/env)
Next: I/O (lua/system/io)