logging block

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

Example

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

Arguments

The following arguments are supported:

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 lines.
"json": Write logs as JSON objects.

Log receivers

The write_to argument allows Alloy 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

Alloy writes all logs to stderr.

When running Alloy as a systemd service, view logs written to stderr through journald.

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

When running Alloy 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 Alloy process to a file for logs to persist on disk.