---
title: "logging block | Grafana Agent documentation"
description: "Learn about the logging configuration block"
---

# logging block

`logging` is an optional configuration block used to customize how Grafana Agent Flow produces log messages. `logging` is specified without a label and can only be provided once per configuration file.

## Example

Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```alloy
logging {
  level  = "info"
  format = "logfmt"
}
```

## Arguments

The following arguments are supported:

Expand table

| Name       | Type                 | Description                                | Default    | Required |
|------------|----------------------|--------------------------------------------|------------|----------|
| `level`    | `string`             | Level at which log lines should be written | `"info"`   | no       |
| `format`   | `string`             | Format to use for writing log lines        | `"logfmt"` | no       |
| `write_to` | `list(LogsReceiver)` | List of receivers to send log entries to   |            | no       |

### Log level

The following strings are recognized as valid log levels:

- `"error"`: Only write logs at the *error* level.
- `"warn"`: Only write logs at the *warn* level or above.
- `"info"`: Only write logs at *info* level or above.
- `"debug"`: Write all logs, including *debug* level logs.

### Log format

The following strings are recognized as valid log line formats:

- `"logfmt"`: Write logs as [logfmt](https://brandur.org/logfmt) lines.
- `"json"`: Write logs as JSON objects.

### Log receivers

The `write_to` argument allows Grafana Agent Flow to tee its log entries to one or more `loki.*` component log receivers in addition to the default [location](#log-location). This, for example can be the export of a `loki.write` component to ship log entries directly to Loki, or a `loki.relabel` component to add a certain label first.

## Log location

Grafana Agent Flow writes all logs to `stderr`.

When running Grafana Agent Flow as a systemd service, view logs written to `stderr` through `journald`.

When running Grafana Agent Flow as a container, view logs written to `stderr` through `docker logs` or `kubectl logs`, depending on whether Docker or Kubernetes was used for deploying Grafana Agent Flow.

When running Grafana Agent Flow as a Windows service, logs are instead written as event logs. You can view the logs through Event Viewer.

In other cases, redirect `stderr` of the Grafana Agent Flow process to a file for logs to persist on disk.