Fluent Bit Integration

What is Fluent Bit?

Fluent Bit is an open-source and multi-platform log processor tool which aims to be a generic Swiss knife for logs processing and distribution (verbatim from Fluent Bit’s documentation). For more information on Fluent Bit, refer to the documentation here.

Integrating Fluent Bit with Kloudfuse stack

Refer to installation instructions for Fluent Bit here. To configure Fluent Bit to send data to Kloudfuse stack, you can modify the agent’s config or values.yaml (if you’re going to install using helm).

You’ll need to configure HTTP output plugin to forward data to Kloudfuse.

HTTP plugin integration

Add the following configuration to Fluent Bit agent’s config for HTTP configuration.

    [OUTPUT]
        Name http
        Match <match_pattern>
        Host <kfuse_ingress_ip>
        Port 443
        TLS on
        URI /ingester/v1/fluent_bit
        Format {json|json_lines|json_stream|msgpack}

Configuration

Kloudfuse UI allows you to filter log events based on log labels/tags. You’ll find the label selectors and filter on the left nav bar of the UI. To get a seamless experience with Kloudfuse while using Fluent Bit agent, we recommend the following configuration(s) or customization(s). Note that the fluent bit agent needs to be restarted for these to take effect.

Kubernetes Labels

Fluent Bit has a filter called kubernetes which will enrich the log event with Kubernetes metadata. Refer to the documentation on this filter here. If you have application deployed in a Kubernetes environment, we highly recommend enabling this filter for all those applications. Here’s an example configuration for this filter:

    [FILTER]
        Name kubernetes
        Match *          # Match everything
        Merge_Log On
        Keep_Log Off
        K8S-Logging.Parser On
        K8S-Logging.Exclude On

Cloud Labels

We recommend adding/configuring the aws filter to get the availability-zone and instance-type. Refer to the documentation for this filter here. At a minimum, we recommend the following configuration for aws filter:

    [FILTER]
        Name aws
        Match *      # Match everything
        az true
        account_id true
        ec2_instance_type true

This filter does not include the cluster name, however. We recommend adding modify filter to include the cluster name as a separate tag. Here's a sample config on how to do that:

    [FILTER]
        Name modify
        Match *     # Match everything
        Add cluster_name <CLUSTER_NAME>

Note that the key, cluster_name in the above filter is configurable too. If you use a key name other than cluster_name or clusterName, then add the following section under logs-parser section in your custom Kloudfuse’s values.yaml

extraApplicationConfigs: |-
    agent.properties.fluent-bit.user_defined_overrides.cloud.cluster_name = [<YOUR_CUSTOM_CLUSTER_NAME_KEY>]

Static custom labels

To add static custom labels, please add following in the config file. The example below adds a static custom label called tenant_name do the following:

    [FILTER]
        Name modify
        Match *     # Match everything
        Add tenant_name <TENANT_NAME>

Log source

By default, Kloudfuse stack looks for container_name in the Fluent Bit payload as the log source. However, this will only be populated if the Fluent Bit agent is configured with kubernetes filter. If you want to Kloudfuse stack to use a different key as the log source, then include the following section under logs-parser section in your custom Kloudfuse’s values.yaml

extraApplicationConfigs: |-
    agent.properties.fluent-bit.user_defined_overrides.log_source = [<YOUR_CUSTOM_LOG_SOURCE_KEY>]

Log message

Fluent Bit agent includes the log event message in log key in the payload. However this can be overriden in the agent configuration. You can customize key which Kloudfuse stack should look for to get the log event message. To customize this setting, include the following section under logs-parser section in your custom Kloudfuse’s values.yaml

extraApplicationConfigs: |-
    agent.properties.fluent-bit.user_defined_overrides.message = [<YOUR_CUSTOM_LOG_MESSAGE_KEY>]

Agent extracted key-value pairs

Fluent Bit supports various parsers to extract key value pairs from an unstructured log. For a full list of parsers, refer to the documentation here. By default, Kloudfuse will add all these key-value pairs to log facets, which can be filtered on the UI. Note that Kloudfuse cannot differentiate between these key-value pairs and any metadata fields, added by any filter other than kubernetes and aws. However, you can customize Kloudfuse stack by adding a list of prefix labels. To customize this setting, include the following section under logs-parser section in your custom Kloudfuse’s values.yaml

extraApplicationConfigs: |-
    agent.properties.fluent-bit.tags_append_list = [<LIST_OF_CANDIDATE_TAG_KEY_PREFIXES>]