Fluent Bit uses CMake as its build system.

Requirements

• CMake 3.12 or greater. You might need to use cmake3 instead of cmake.

• Flex

• Bison 3 or greater

• YAML headers

• OpenSSL headers

Prepare environment

If you already know how CMake works, you can skip this section and review the available build options.

The following steps explain how to build and install the project with the default options.

1. Change to the build/ directory inside the Fluent Bit sources:

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   cd build/

2. Let CMake configure the project specifying where the root path is located:

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   cmake ../

   This command displays a series of results similar to:

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   -- The C compiler identification is GNU 4.9.2
   -- Check for working C compiler: /usr/bin/cc
   -- Check for working C compiler: /usr/bin/cc -- works
   -- Detecting C compiler ABI info
   -- Detecting C compiler ABI info - done
   -- The CXX compiler identification is GNU 4.9.2
   -- Check for working CXX compiler: /usr/bin/c++
   -- Check for working CXX compiler: /usr/bin/c++ -- works
   ...
   -- Could NOT find Doxygen (missing:  DOXYGEN_EXECUTABLE)
   -- Looking for accept4
   -- Looking for accept4 - not found
   -- Configuring done
   -- Generating done
   -- Build files have been written to: /home/edsiper/coding/fluent-bit/build

3. Start the compilation process using the make command:

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   make

   This command displays results similar to:

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   Scanning dependencies of target msgpack
   [  2%] Building C object lib/msgpack-1.1.0/CMakeFiles/msgpack.dir/src/unpack.c.o
   [  4%] Building C object lib/msgpack-1.1.0/CMakeFiles/msgpack.dir/src/objectc.c.o
   [  7%] Building C object lib/msgpack-1.1.0/CMakeFiles/msgpack.dir/src/version.c.o
   ...
   [ 19%] Building C object lib/monkey/mk_core/CMakeFiles/mk_core.dir/mk_file.c.o
   [ 21%] Building C object lib/monkey/mk_core/CMakeFiles/mk_core.dir/mk_rconf.c.o
   [ 23%] Building C object lib/monkey/mk_core/CMakeFiles/mk_core.dir/mk_string.c.o
   ...
   Scanning dependencies of target fluent-bit-static
   [ 66%] Building C object src/CMakeFiles/fluent-bit-static.dir/flb_pack.c.o
   [ 69%] Building C object src/CMakeFiles/fluent-bit-static.dir/flb_input.c.o
   [ 71%] Building C object src/CMakeFiles/fluent-bit-static.dir/flb_output.c.o
   ...
   Linking C executable ../bin/fluent-bit
   [100%] Built target fluent-bit-bin

4. To continue installing the binary on the system, use make install:

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   make install

   If the command indicates insufficient permissions, prefix the command with sudo.

Build options

Fluent Bit provides configurable options to CMake that can be enabled or disabled.

General options

Development options

Optimization options

Input plugins

Input plugins gather information from a specific source type like network interfaces, some built-in metrics, or through a specific input device. The following input plugins are available:

Filter plugins

Filter plugins let you modify, enrich or drop records. The following table describes the filters available on this version:

Output plugins

Output plugins let you flush the information to some external interface, service, or terminal. The following table describes the output plugins available:

Processor plugins

Processor plugins handle the events within the processor pipelines to allow modifying, enriching, or dropping events.

The following table describes the processors available:

| Option | Description | Default || :--- | :--- | :--- | | FLB_PROCESSOR_METRICS_SELECTOR | Enable metrics selector processor | On | | FLB_PROCESSOR_LABELS | Enable metrics label manipulation processor | On |

Fluent Bit in normal operation mode allows to be configurable through text files or using specific arguments in the command line, while this is the ideal deployment case, there are scenarios where a more restricted configuration is required: static configuration mode.

Static configuration mode aims to include a built-in configuration in the final binary of Fluent Bit, disabling the usage of external files or flags at runtime.

Getting Started

Requirements

The following steps assumes you are familiar with configuring Fluent Bit using text files and you have experience building it from scratch as described in the Build and Install section.

Configuration Directory

In your file system prepare a specific directory that will be used as an entry point for the build system to lookup and parse the configuration files. It is mandatory that this directory contain as a minimum one configuration file called fluent-bit.conf containing the required SERVICE, INPUT and OUTPUT sections. As an example create a new fluent-bit.conf file with the following content:

[SERVICE]
    Flush     1
    Daemon    off
    Log_Level info

[INPUT]
    Name      cpu

[OUTPUT]
    Name      stdout
    Match     *

the configuration provided above will calculate CPU metrics from the running system and print them to the standard output interface.

Build with Custom Configuration

Inside Fluent Bit source code, get into the build/ directory and run CMake appending the FLB_STATIC_CONF option pointing the configuration directory recently created, e.g:

$ cd fluent-bit/build/
$ cmake -DFLB_STATIC_CONF=/path/to/my/confdir/

then build it:

$ make

At this point the fluent-bit binary generated is ready to run without necessity of further configuration:

$ bin/fluent-bit 
Fluent-Bit v0.15.0
Copyright (C) Treasure Data

[2018/10/19 15:32:31] [ info] [engine] started (pid=15186)
[0] cpu.local: [1539984752.000347547, {"cpu_p"=>0.750000, "user_p"=>0.500000, "system_p"=>0.250000, "cpu0.p_cpu"=>1.000000, "cpu0.p_user"=>1.000000, "cpu0.p_system"=>0.000000, "cpu1.p_cpu"=>0.000000, "cpu1.p_user"=>0.000000, "cpu1.p_system"=>0.000000, "cpu2.p_cpu"=>0.000000, "cpu2.p_user"=>0.000000, "cpu2.p_system"=>0.000000, "cpu3.p_cpu"=>1.000000, "cpu3.p_user"=>1.000000, "cpu3.p_system"=>0.000000}]

You can download the most recent stable or development source code.

Stable

For production systems, it's strongly suggested that you get the latest stable release of the source code in either zip file or tarball file format from GitHub using the following link pattern:

https://github.com/fluent/fluent-bit/archive/refs/tags/v<release version>.tar.gz
https://github.com/fluent/fluent-bit/archive/refs/tags/v<release version>.zip

For example, for version 1.8.12 the link is: https://github.com/fluent/fluent-bit/archive/refs/tags/v1.8.12.tar.gz

Development

If you want to contribute to Fluent Bit, you should use the most recent code. You can get the development version from the Git repository:

git clone https://github.com/fluent/fluent-bit

The master branch is where the development of Fluent Bit happens. Development version users should expect issues when compiling or at run time.

Fluent Bit users are encouraged to help test every development version to ensure a stable release.