---
title: "loki.source.gelf | Grafana Alloy documentation"
description: "Learn about loki.source.gelf"
---

# `loki.source.gelf`

`loki.source.gelf` reads [Graylog Extended Long Format (GELF) logs](https://github.com/Graylog2/graylog2-server) from a UDP listener and forwards them to other `loki.*` components.

You can specify multiple `loki.source.gelf` components by giving them different labels and ports.

## Usage

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```alloy
loki.source.gelf "<LABEL>" {
  forward_to    = <RECEIVER_LIST>
}
```

## Arguments

The component starts a new UDP listener and fans out log entries to the list of receivers passed in `forward_to`.

You can use the following arguments with `loki.source.gelf`:

Expand table

| Name                     | Type                 | Description                                                                | Default           | Required |
|--------------------------|----------------------|----------------------------------------------------------------------------|-------------------|----------|
| `forward_to`             | `list(LogsReceiver)` | List of receivers to send log entries to.                                  |                   | yes      |
| `listen_address`         | `string`             | UDP address and port to listen for Graylog messages.                       | `"0.0.0.0:12201"` | no       |
| `relabel_rules`          | `RelabelRules`       | Relabeling rules to apply on log entries.                                  | `{}`              | no       |
| `use_incoming_timestamp` | `bool`               | When false, assigns the current timestamp to the log when it was processed | `false`           | no       |

> Note
> 
> GELF logs can be sent uncompressed or compressed with GZIP or ZLIB. A `job` label is added with the full name of the component `loki.source.gelf.LABEL`.

The `relabel_rules` argument can make use of the `rules` export from a [`loki.relabel`](../loki.relabel/) component to apply one or more relabeling rules to log entries before they’re forwarded to the list of receivers specified in `forward_to`.

Incoming messages have the following internal labels available:

- `__gelf_message_facility`: The GELF facility.
- `__gelf_message_version`: The GELF message version sent by the client.
- `__gelf_message_host`: The host sending the GELF message.
- `__gelf_message_level`: The GELF level as a string.

All labels starting with `__` are removed prior to forwarding log entries. To keep these labels, relabel them using a [`loki.relabel`](../loki.relabel/) component and pass its `rules` export to the `relabel_rules` argument.

## Blocks

The `loki.source.gelf` component doesn’t support any blocks. You can configure this component with arguments.

## Component health

`loki.source.gelf` is only reported as unhealthy if given an invalid configuration.

## Debug Metrics

- `gelf_target_entries_total` (counter): Total number of successful entries sent to the GELF target.
- `gelf_target_parsing_errors_total` (counter): Total number of parsing errors while receiving GELF messages.

## Example

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```alloy
loki.relabel "gelf" {
  rule {
    source_labels = ["__gelf_message_host"]
    target_label  = "host"
  }
}

loki.source.gelf "listen"  {
  forward_to    = [loki.write.endpoint.receiver]
  relabel_rules = loki.relabel.gelf.rules
}

loki.write "endpoint" {
  endpoint {
    url ="loki:3100/api/v1/push"
  }
}
```

## Compatible components

`loki.source.gelf` can accept arguments from the following components:

- Components that export [Loki `LogsReceiver`](../../../compatibility/#loki-logsreceiver-exporters)

> Note
> 
> Connecting some components may not be sensible or components may require further configuration to make the connection work correctly. Refer to the linked documentation for more details.