Crate fluentbit

fluentbit

This crate aims to build output plugins for Fluent-bit. It is based on the Go interface for writting output plugins.

This crate is still in heavy development. At this point, Multiple-instance plugin is not supported but it would be added very soon.

Hello World

A simple Hello world example which prints data to stdout, it involves following three steps:

• Create a struct/enum with the data you might use for processing the incoming buffer from Fluent-bit
• Implement the trait FLBPluginMethods for that struct/enum.
• After steps 1 and 2, call the macro create_boilerplate!() which will generate the boilerplate code that every plugin should have, taking care of the unsafe safe code and abstracting it into a safe Rust style. This macro will accept as an argument any type which implements the FLBPluginMethods trait

And that's all. Compile your plugin as a dynamic library by adding this line to your Cargo.toml

[lib]
crate-type=["cdylib"]

Another thing that is worth to mention is that Fluent-bit should be able to load Go plugins even though your plugin was written in Rust. To enable external plugins' support you have to compile Fluent-bit with Goland support, e.g:

$ cd build/
$ cmake -DFLB_DEBUG=On -DFLB_PROXY_GO=On ../
$ make

Once compiled, you can see a new option in the binary -e which stands for external plugin, e.g:

$ bin/fluent-bit -h
Usage: fluent-bit [OPTION]
Available Options
 -c  --config=FILE	specify an optional configuration file
 -d, --daemon		run Fluent Bit in background mode
 -f, --flush=SECONDS	flush timeout in seconds (default: 5)
 -i, --input=INPUT	set an input
 -m, --match=MATCH	set plugin match, same as '-p match=abc'
 -o, --output=OUTPUT	set an output
 -p, --prop="A=B"	set plugin configuration property
 -e, --plugin=FILE	load an external plugin (shared lib)
 ...

Now here is a simple output plugin

extern crate fluentbit;
use fluentbit::*;

#[derive(Default)]
struct MyPluginDemo{
    num_flushes: u32,
}

impl FLBPluginMethods for MyPluginDemo{
     
    fn plugin_register(&mut self, info: &mut PluginInfo) -> FLBResult {
        info.name = "rustout".into();
        info.description = "It is a default description".into();
        Ok(())
    }

    fn plugin_init(&mut self) -> FLBResult {
        Ok(())
    }

    fn plugin_flush(&mut self, data: &[u8]) -> FLBResult {
        println!("data: {:?}", data);
        self.num_flushes += 1;
        println!("FLUSH NUMBER {}", self.num_flushes);
        Ok(())
    }

    fn plugin_exit(&mut self) -> FLBResult {
        println!("exiting");
        Ok(())
    }
     
}

create_boilerplate!(MyPluginDemo::default());

Test your plugin:

cargo build --release
fluent-bit -e target/release/libexample.so -i cpu -o "rustout"

Macros

create_boilerplate

This macro will generate the needed boilerplate for output plugins

Structs

PluginInfo

Basic plugin information

Enums

FLBError

Fluent-bit error definitions

Constants

FLB_ERROR
FLB_OK
FLB_PROXY_GOLANG
FLB_PROXY_OUTPUT_PLUGIN
FLB_RETRY

Traits

FLBPluginMethods

Trait which defines the functions that should be implemented by any rust plugin

Type Definitions

FLBResult

Custom result for any plugin's operation