Facilitate the management of Fluent Bit and Fluentd in Kubernetes

Fluent Operator

Fluent Operator provides great flexibility in building a logging layer based on Fluent Bit and Fluentd.

Once installed, the Fluent Operator provides the following features:

• Fluent Bit Management: Deploy and destroy Fluent Bit DaemonSet automatically.
• Fluentd Management: Deploy and destroy Fluentd StatefulSet automatically.
• Custom Configuration: Select input/filter/output plugins via labels.
• Dynamic Reloading: Update configuration without rebooting Fluent Bit and Fluentd pods.
• Multi-tenant log isolation: Fluentd supports multi-tenant log isolation through label_router plugin.
• Pluggable deployment components: Either Fluent Bit or Fluentd can be deployed separately.

Table of contents

• Fluent Operator
  • Table of contents
  • Overview
    • Fluent Bit
    • Fluentd
  • Get Started
    • Prerequisites
    • Install
      • Deploy Fluent Operator with YAML
      • Deploy Fluent Operator with Helm
    • Fluent Operator Walkthrough
    • Collect Kubernetes logs
      • Deploy the Kubernetes logging stack with YAML
      • Deploy the Kubernetes logging stack with Helm
    • Collect auditd logs
    • Fluentd
  • Plugins
    • Fluent Bit
    • Fluentd
  • Best Practice
    • Plugin Grouping
    • Monitoring
    • Custom Parser
    • Misc
    • Custom Plugin
  • Roadmap
  • Development
    • Requirements
    • Running
  • Contributing
    • Documentation
    • Manifests
  • Community
    • About the community
    • Contact us
  • Videos and blogs

Overview

Although both Fluent Bit and Fluentd can collect, process(parse and filter) and then forward log to the final destinations, still they have strengths in different aspects.

Fluent Bit is a good choice as a logging agent because of its lightweight and efficiency, while Fluentd is more powerful to perform advanced processing on logs because of its rich plugins.

• Fluent Bit only mode: If you just need to collect logs and send logs to the final destinations, all you need is Fluent Bit.
• Fluent Bit + Fluentd mode: If you also need to perform some advanced processing on the logs collected or send to more sinks, then you also need Fluentd.
• Fluentd only mode: If you need to receive logs through networks like HTTP or Syslog and then process and send the log to the final sinks, you only need Fluentd.

Fluent Operator includes CRDs and controllers for both Fluent Bit and Fluentd which allows you to config your log processing pipelines in the 3 modes mentioned above as you wish.

Fluent Bit will be deployed as a DaemonSet while Fluentd will be deployed as a StatefulSet. The whole workflow could be described as below:

Fluent Bit

The following CRDs are defined for Fluent Bit:

• FluentBit: Defines the Fluent Bit DaemonSet and its configs. A custom Fluent Bit image kubesphere/fluent-bit is required to work with FluentBit Operator for dynamic configuration reloading.
• ClusterFluentBitConfig: Select cluster-level input/filter/output plugins and generates the final config into a Secret.
• FluentBitConfig: Selects namespace-level filter/output/parser and cluster-level parser plugins and generates final config into a Secret.
• ClusterInput: Defines cluster-level input config sections.
• Parser: Defines namespace-level parser config sections.
• ClusterParser: Defines cluster-level parser config sections.
• Filter: Defines namespace-level filter config sections.
• ClusterFilter: Defines cluster-level filter config sections.
• Output: Defines namespace-level output config sections.
• ClusterOutput: Defines cluster-level output config sections.

Each ClusterInput, ClusterParser, ClusterFilter, ClusterOutput represents a Fluent Bit config section, which are selected by ClusterFluentBitConfig via label selectors. Fluent Operator watches those objects, constructs the final config, and finally creates a Secret to store the config which will be mounted into the Fluent Bit DaemonSet. The entire workflow looks like below:

To enable Fluent Bit to pick up and use the latest config whenever the Fluent Bit config changes, a wrapper called Fluent Bit watcher is added to restart the Fluent Bit process as soon as Fluent Bit config changes are detected. This way, the Fluent Bit pod needn't be restarted to reload the new config. The Fluent Bit config is reloaded in this way because there is no reloading interface in Fluent Bit itself. Please refer to this known issue for more details.

Fluentd

The following CRDs are defined for Fluentd:

• Fluentd: Defines the Fluentd Statefulset and its configs. A custom Fluentd image kubesphere/fluentd is required to work with Fluentd Operator for dynamic configuration reloading.
• FluentdConfig: Select cluster-level or namespace-level scope input/filter/output plugins and generates the final config into a Secret.
• ClusterFluentdConfig: Select cluster-level input/filter/output plugins and generates the final config into a Secret.
• Filter: Defines namespace-level filter config sections.
• ClusterFilter: Defines cluster-level filter config sections.
• Output: Defines namespace-level output config sections.
• ClusterOutput: Defines cluster-level output config sections.

Get Started

Prerequisites

Kubernetes v1.16.13+ is necessary for running Fluent Operator.

Install

Deploy Fluent Operator with YAML

Install the latest stable version

kubectl apply -f https://raw.githubusercontent.com/fluent/fluent-operator/release-2.5/manifests/setup/setup.yaml

# You can change the namespace in manifests/setup/kustomization.yaml in corresponding release branch 
# and then use command below to install to another namespace
# kubectl kustomize manifests/setup/ | kubectl apply -f -

Install the development version

kubectl apply -f https://raw.githubusercontent.com/fluent/fluentbit-operator/master/manifests/setup/setup.yaml

# You can change the namespace in manifests/setup/kustomization.yaml 
# and then use command below to install to another namespace
# kubectl kustomize manifests/setup/ | kubectl apply -f -

Deploy Fluent Operator with Helm

Note: For the helm based install, Helm v3.2.1 or higher is needed.

The Fluent Bit section of the Fluent Operator supports different CRI docker, containerd, and CRI-O. containerd and CRI-O use the CRI Log format which is different with docker, they requires additional parser to parse JSON application logs. You should set different containerRuntime depending on your container runtime.

The default runtime is docker, you can choose other runtimes as follows.

If your container runtime is containerd or cri-o, you can set the containerRuntime parameter to containerd or crio. e.g.

helm install fluent-operator --create-namespace -n fluent charts/fluent-operator/  --set containerRuntime=containerd

Install through the online chart link:

helm install fluent-operator --create-namespace -n fluent https://github.com/fluent/fluent-operator/releases/download/< version >/fluent-operator.tgz

Please replace < version > with a actual version like v1.0.0

Fluent Operator CRDs will be installed by default when running a helm install for the chart. But if the CRD already exists, it will be skipped with a warning. So make sure you install the CRDs by yourself if you upgrade your Fluent Operator version.

By default the installation with Helm create all the CRDs (fluent-bit and fluentd ones). If you do not intent to use one of the two components, it is possible to skip its CRDs and also to not start the controllers for it in the operator. To achieve that operator.disableComponentControllers and (fluent-bit/fluentd).crdsEnable parameters can be provided:

helm install fluent-operator --create-namespace -n fluent charts/fluent-operator/  --set operator.disableComponentControllers=fluent-bit,fluent-bit.crdsEnable=false

Note: During the upgrade process, if a CRD was previously created using the create operation, an error will occur during the apply operation. Using apply here allows the CRD to be replaced and created in its entirety in a single operation.

To replace the CRDs pull the current helm chart:

wget https://github.com/fluent/fluent-operator/releases/download/<version>/fluent-operator.tgz
tar -xf fluent-operator.tgz

To update the CRDs, run the following command:

kubectl replace -f fluent-operator/crds

Fluent Operator Walkthrough

For more info on various use cases of Fluent Operator, you can refer to Fluent-Operator-Walkthrough.

Collect Kubernetes logs

This guide provisions a logging pipeline including the Fluent Bit DaemonSet and its log input/filter/output configurations to collect Kubernetes logs including container logs and kubelet logs.

Note that you need a running Elasticsearch v5+ cluster to receive log data before start. Remember to adjust output-elasticsearch.yaml to your own es setup. Kafka and Fluentd outputs are optional and are turned off by default.

Deploy the Kubernetes logging stack with YAML

kubectl apply -f manifests/logging-stack

# You can change the namespace in manifests/logging-stack/kustomization.yaml 
# and then use command below to install to another namespace
# kubectl kustomize manifests/logging-stack/ | kubectl apply -f -

Deploy the Kubernetes logging pipeline with Helm

You can also deploy the Kubernetes logging pipeline with Helm, just need to set the Kubernetes parameter to true (default):

helm upgrade fluent-operator --create-namespace -n fluent charts/fluent-operator/  --set containerRuntime=docker

If you want to deploy fluentd, just need to set the fluentd.enable parameter to true:

helm upgrade fluent-operator --create-namespace -n fluent charts/fluent-operator/  --set containerRuntime=docker,fluentd.enable=true

Within a couple of minutes, you should observe an index available:

$ curl localhost:9200/_cat/indices
green open ks-logstash-log-2020.04.26 uwQuoO90TwyigqYRW7MDYQ 1 1  99937 0  31.2mb  31.2mb

Success!

Collect audit logs

The Linux audit framework provides a CAPP-compliant (Controlled Access Protection Profile) auditing system that reliably collects information about any security-relevant (or non-security-relevant) event on a system. Refer to manifests/logging-stack/auditd, it supports a method for collecting audit logs from the Linux audit framework.

kubectl apply -f manifests/logging-stack/auditd

# You can change the namespace in manifests/logging-stack/auditd/kustomization.yaml 
# and then use command below to install to another namespace
# kubectl kustomize manifests/logging-stack/auditd/ | kubectl apply -f -

Within a couple of minutes, you should observe an index available:

$ curl localhost:9200/_cat/indices
green open ks-logstash-log-2021.04.06 QeI-k_LoQZ2h1z23F3XiHg  5 1 404879 0 298.4mb 149.2mb

Fluentd

Fluentd acts as a log forward layer that receives logs from Fluent Bit or other Apps through the network.

For more info on various use cases of Fluent Operator Fluentd CRDs, you can refer to Fluent-Operator-Walkthrough.

Plugins

Fluent Bit

Here you can find supported Fluent Bit plugins.

Fluentd

Here you can find supported Fluentd plugins.

Best Practice

Plugin Grouping

Here you can find the plugin group information.

Monitoring

Here you can use the built-in HTTP Server in Fluent Bit.

Custom Parser

Here you can customize parser in Fluent Bit.

Misc

If you want to learn more about Fluent-Operator, please refer to the misc.

Custom Plugin

Here you can learn how to use custom plugin in FluentBit and Fluentd.

Roadmap

• Support containerd log format
• Add Fluentd CRDs as the log aggregation layer with group name fluentd.fluent.io
• Add FluentBit Cluster CRDs with new group name fluentbit.fluent.io
• Rename the entire project to Fluent Operator
• Support more Fluentd & FluentBit plugins

Development

Requirements

• golang v1.16+.requirement
• kubectl v1.19.2+.
• kubebuilder v3.1+ (the project is build with v3.1.0)
• Access to a Kubernetes cluster v1.19.2+

Running

1. Install CRDs: make install
2. Run: make run

Contributing

Documentation

API Doc is generated automatically. To modify it, edit the comment above struct fields, then run go run cmd/doc-gen/main.go.

Manifests

Most files under the folder manifests/setup are automatically generated from config. Don't edit them directly, run make manifests instead, then replace these files accordingly.

Community

About the community

Fluent Operator is sponsored and open-sourced by the KubeSphere Team and maintained by the Fluent community.

This project was accepted by the Fluent community as a sub-project in 2021 and is currently a vendor-neutral and community-driven project.

Contact us

You are welcome to join us in the Fluent community to polish it together:

• Slack: Create an account in the Fluent Slack workspace and then search #fluent-operator to join or click #fluent-operator to join if you already have an account
• Wechat: join the KubeSphere Observability SIG by following the kubesphere WeChat subscription
• Bi-weekly Meeting: https://meeting.tencent.com/dm/mZPB9QKdtX0F (You can find the SIG-Observability meeting schedule here)

Videos and blogs

• From FluentBit Operator to Fluent Operator: The Long Way to Come - Benjamin Huo
• What is Fluent Operator and how do you use it - Henrik Rexed
• Under the Hood with Fluent Bit Operator: Kubernetes-native Log Processor - Feynman Zhou & Dhruv Kela
• Quick Start: Learn Fluent Operator in 5 minutes (中文) - Dehao Cheng