Menu

Caution

Grafana Alloy is the new name for our distribution of the OTel collector. Grafana Agent has been deprecated and is in Long-Term Support (LTS) through October 31, 2025. Grafana Agent will reach an End-of-Life (EOL) on November 1, 2025. Read more about why we recommend migrating to Grafana Alloy .
Open source

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

river
logging {
  level  = "info"
  format = "logfmt"
}

Arguments

The following arguments are supported:

NameTypeDescriptionDefaultRequired
levelstringLevel at which log lines should be written"info"no
formatstringFormat to use for writing log lines"logfmt"no
write_tolist(LogsReceiver)List of receivers to send log entries tono

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 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 . 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.