This is documentation for the next version of Loki. For the latest stable release, go to the latest version.
Fluent Bit Loki output plugin
Fluent Bit is a fast and lightweight logs and metrics processor and forwarder that can be configured with the Fluent-bit Loki output plugin to ship logs to Loki.
You can define which log files you want to collect using the Tail
or Stdin
data pipeline input. Additionally, Fluent Bit supports multiple Filter
and Parser
plugins (Kubernetes
, JSON
, etc.) to structure and alter log lines.
Note
There are two Fluent Bit plugins for Loki: the officially maintained plugin
loki
and thegrafana-loki
plugin. We recommend using theloki
plugin described within this page as it’s officially maintained by the Fluent Bit project.For more information, see the Fluent Bit Loki output plugin documentation. Note that the
grafana-loki
plugin is no longer actively maintained.
Configuration
All configuration options for the Fluent Bit Loki output plugin are documented in the Fluent Bit Loki output plugin documentation.
Here is a generic example for connecting Fluent Bit to Loki hosted on Grafana Cloud:
[OUTPUT]
Name loki
Match *
Host YourHostname.company.com
port 443
tls on
tls.verify on
http_user XXX
http_passwd XXX
Replace Host
, http_user
, and http_passwd
with your Grafana Cloud Loki endpoint and credentials.
Usage examples
Here are some examples of how to use Fluent Bit to send logs to Loki.
Tail Docker logs
Here is an example to run Fluent Bit in a Docker container, collect Docker logs, and send them to a local Loki instance.
docker run -v /var/lib/docker/containers:/var/lib/docker/containers fluent/fluent-bit:latest /fluent-bit/bin/fluent-bit -i tail -p Path="/var/lib/docker/containers/*/*.log" -p Parser=docker -p Tag="docker.*" -o loki -p host=loki -p port=3100 -p labels="agent=fluend-bit,env=docker"
In this example, we are using the tail
input plugin to collect Docker logs and the loki
output plugin to send logs to Loki. Note it is recommended to use a configuration file to define the input and output plugins. The -p
flag is used to pass configuration parameters to the plugins.
Configuration file (Alternative to command line arguments)
Create a configuration file fluent-bit.conf
with the following content:
[INPUT]
Name tail
Path /var/lib/docker/containers/*/*.log
Parser docker
Tag docker.*
[OUTPUT]
Name loki
Match *
Host loki
Port 3100
Labels agent=fluend-bit,env=docker
Run Fluent Bit with the configuration file:
docker run -v /var/lib/docker/containers:/var/lib/docker/containers -v $(pwd)/fluent-bit.conf:/fluent-bit/etc/fluent-bit.conf fluent/fluent-bit:latest /fluent-bit/bin/fluent-bit -c /fluent-bit/etc/fluent-bit.conf
Collect Docker events
Here is an example to run Fluent Bit in a Docker container, collect docker events, and send them to a local Loki instance.
docker run -v /var/run/docker.sock:/var/run/docker.sock fluent/fluent-bit:latest /fluent-bit/bin/fluent-bit -i docker_events -o loki -p host=loki -p port=3100 -p labels="agent=fluend-bit,env=docker"
In this example, we are using the docker_events
input plugin to collect Docker events and the loki
output plugin to send logs to Loki. Note it is recommended to use a configuration file to define the input and output plugins. The -p
flag is used to pass configuration parameters to the plugins.
Configuration file (Alternative to command line arguments)
Create a configuration file fluent-bit.conf
with the following content:
[INPUT]
Name docker_events
[OUTPUT]
Name loki
Match *
Host loki
Port 3100
Labels agent=fluent-bit,env=docker
Run Fluent Bit with the configuration file:
docker run -v /var/run/docker.sock:/var/run/docker.sock -v $(pwd)/fluent-bit.conf:/fluent-bit/etc/fluent-bit.conf fluent/fluent-bit:latest /fluent-bit/bin/fluent-bit -c /fluent-bit/etc/fluent-bit.conf
Collect Kubernetes logs
The recommended way to collect logs from Kubernetes with Fluent Bit is to use the Helm chart provided by the Fluent Bit project. The Helm chart is available at https://github.com/fluent/helm-charts.
Here is an example of how to deploy the Fluent Bit Helm chart to collect logs from Kubernetes and send them to Loki:
Add the Fluent Bit Helm repository:
helm repo add fluent https://fluent.github.io/helm-charts
Create a
values.yaml
file with the following content:config: outputs: | [OUTPUT] Name loki Match * Host YourHost.Company.net port 443 tls on tls.verify on http_user XXX http_passwd XXX Labels agent=fluend-bit Note we are only updating the `outputs` section of the Fluent Bit configuration. This is to replace the default output plugin with the Loki output plugin. If you need to update other parts of the Fluent Bit configuration refer to the [Fluent Bit values file reference](https://github.com/fluent/helm-charts/blob/main/charts/fluent-bit/values.yaml).
Deploy the Fluent Bit Helm chart:
helm install fluent-bit fluent/fluent-bit -f values.yaml