Fluent Bit

This page explains how to configure Fluent Bit to ship logs into Vector for Logwise, and what (if anything) you need to change on the Vector side for:

• the Docker-based Logwise stack, and
• a manual/self-hosted Vector setup.

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1. What Fluent Bit does in this setup

Fluent Bit:

• tails log files from your applications,
• adds useful metadata (for example: service_name),
• sends logs to Vector using OTLP HTTP via Fluent Bit’s opentelemetry output.

Vector receives these logs through the same OTLP source used by the OpenTelemetry Collector.

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2. Example Fluent Bit configuration

Below is an example configuration (adapt it to your environment):

[SERVICE]
    Flush        1
    Daemon       off
    Log_Level    info
    Http_Server  On
    Http_Listen  0.0.0.0
    Http_Port    2020

[INPUT]
    Name              tail
    Path              /var/log/healthcheck/*.log
    Tag               healthcheck
    Mem_Buf_Limit     5MB
    Skip_Long_Lines   On
    Refresh_Interval  5

[FILTER]
    Name   modify
    Match  healthcheck
    Add    service_name  healthcheck-dummy

[OUTPUT]
    Name           opentelemetry
    Match          *
    Host           <VECTOR_HOST>
    Port           4318
    Logs_uri       /v1/logs
    Tls            Off

Key points:

• Input: tails /var/log/healthcheck/*.log (change to your app’s path).
• Filter: adds service_name=healthcheck-dummy so downstream logic can key on it.
• Output: uses Fluent Bit’s opentelemetry output, targeting http://<VECTOR_HOST>:4318/v1/logs.

Replace <VECTOR_HOST> with the hostname or IP where Vector is reachable.

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3. Vector configuration impact

3.1 Docker-based Logwise stack

In the Docker-based Logwise setup:

• Vector is already configured with an otlp_logs source that listens on port 4318 for OTLP HTTP logs.
• No additional changes are required in vector.yaml to support Fluent Bit’s OTLP output.

You only need to ensure that:

• the Vector container is reachable from Fluent Bit at port 4318, and
• the Fluent Bit Host points at that host (for example vector if you are inside the same Docker network).

3.2 Manual/self-hosted Vector

In a self-hosted setup, follow the Self-Host → Vector guide to install and configure Vector with the otlp_logs source enabled:

sources:
  otlp_logs:
    type: "opentelemetry"
    grpc:
      address: "0.0.0.0:4317"
    http:
      address: "0.0.0.0:4318"

As long as this source is present and listening on port 4318:

• you do not need further changes in Vector for Fluent Bit,
• you only need to open port 4318 on your firewall and point Fluent Bit at that address.

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4. Summary

• Use Fluent Bit when you need a lightweight log agent that can still speak OTLP to Vector.
• Configure Fluent Bit with:
  • a tail input for your log files,
  • a modify filter to add metadata (for example service_name),
  • an opentelemetry output pointing to http://<VECTOR_HOST>:4318/v1/logs.
• In Logwise, Vector’s OTLP source is the same for both the OTEL Collector and Fluent Bit, and requires no extra changes for either Docker or manual setups.