Fluent Bit output plugin

Fluent Bit is a Fast and Lightweight Data Forwarder, it can be configured with the Loki output plugin to ship logs to Loki. You can define which log files you want to collect using the Tail or Stdin input plugin. Additionally Fluent Bit supports multiple Filter and Parser plugins (Kubernetes, JSON, etc..) to structure and alter log lines.

This plugin is implemented with Fluent Bit's Go plugin interface. It pushes logs to Loki using a GRPC connection.

Warning syslog and systemd input plugins have not been tested yet. Feedback appreciated, file an issue if you encounter any misbehaviors.

Building

Prerequisites

Go 1.17+
gcc (for cgo)

To build the output plugin library file out_grafana_loki.so, in the root directory of Loki source code, you can use:

bash

$ make fluent-bit-plugin

You can also build the Docker image with the plugin pre-installed using:

bash

$ make fluent-bit-image

Running

bash

$ fluent-bit -e out_grafana_loki.so -c /etc/fluent-bit.conf

Testing

Issue the following command to send /var/log logs to your http://localhost:3100/loki/api/ Loki instance for testing:

bash

$ make fluent-bit-test

You can easily override the address by setting the $LOKI_URL environment variable.