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LICENSE License Build Status Version Minimum rustc version

This library is a multithreaded ETL (Extract, Transfrom, Load), with inspiration drawn from Keras, to allow a "Brew Master" to define any order of operations for data transformations and outputs.


rettle has the following Types to be used in any project to "Brew" data:

  • Pot: container that holds the set of instructions for data sources, sinks, and transforms (See Ingredient Types below)
  • Brewery: manager that holds the brewers and sends them jobs and the initial state of tea to be processed
  • Brewer: worker that brews the Tea


  • Ingredient: defines the steps that can be included in the ETL recipe
  • Argument: defines additional params that an Ingredient operation can use (Optional)

Ingredient Types

  • Fill: data input source
  • Transfuse: combine data from multiple sources defined before this step Not Implemented Yet
  • Steep: data transformation step
  • Skim: remove a field (or Tea object) Not Implemented Yet
  • Pour: data output destination

Using rettle

In your custom project you first need to define the custom "Tea" struct that will be created by the Fill Ingredient.


pub struct TextTea {
    pub x: i32,
    pub str_val: String,
    pub y: bool,

Next you can create a new Pot struct and supply it with sources and ingredients before calling it's brew() method to kick off the brewing process. Ingredients can be supplied with Optional Argument trait structs to pass additional runtime parameters used by your custom filters.

Optional Steep Argument Example:

pub struct SteepArgs {
    pub increment: i32,

impl Argument for SteepArgs {
    fn as_any(&self) -> &dyn Any {

Finally a Brewery struct must be created to specify the number of Brewers (threads) to run the code, and a start_time value to provide elapsed run time metrics.

Fill operations collect and pass the Tea objects to be worked on to the Brewery for it to be processed by the Brewers.

Example Project Code

fn main() {
    // Initialize variables
    let mut new_pot = Pot::new();
    let brewery = Brewery::new(2);
    let steep_args = SteepArgs { increment: 10000 };
    // Add source to pot
    new_pot = new_pot.add_source(Box::new(Fill{
        name: String::from("fake_tea"),
        source: String::from("hardcoded"),
        computation: Box::new(|_args, brewery, recipe| {
            let total_data = 1000000;
            let batch_size = 200;
            let num_iterations = total_data / batch_size;
            println!("Testing {} iterations", total_data);
            for _ in 0 .. num_iterations {
                let mut tea_batch = Vec::with_capacity(batch_size);
                for _ in 0 .. batch_size {
                    tea_batch.push(Box::new(TextTea::default()) as Box<dyn Tea + Send>);
                let recipe = Arc::clone(&recipe);
                brewery.take_order(|| {
                    make_tea(tea_batch, recipe);
        params: None,
    // Add ingredients to pot
    new_pot = new_pot.add_ingredient(Box::new(Steep{
        name: String::from("steep1"),
        computation: Box::new(|tea_batch, args| {
                .map(|tea| {
                    let tea = tea.as_any().downcast_ref::<TextTea>().unwrap();
                    let mut new_tea = tea.clone();
                    match args {
                        None => panic!("No params passed, not editing object!"),
                        Some(box_args) => {
                            let box_args = box_args.as_any().downcast_ref::<SteepArgs>().unwrap();
                            new_tea.x = new_tea.x - box_args.increment;
                    Box::new(new_tea) as Box<dyn Tea + Send>
        params: Some(Box::new(steep_args)),

    new_pot = new_pot.add_ingredient(Box::new(Pour{
        name: String::from("pour1"),
        computation: Box::new(|tea_batch, _args| {
                .map(|tea| {
                    //println!("Final Tea: {:?}", tea.as_any().downcast_ref::<TextTea>().unwrap());
                    let tea = tea.as_any().downcast_ref::<TextTea>().unwrap();
                    let same_tea = TextTea { x: tea.x, str_val: String::from(&tea.str_val[..]), y: tea.y };
                    Box::new(same_tea) as Box<dyn Tea + Send>
        params: None,
    // Process Tea
    // Display information
    println!("Number of sources: {}", new_pot.get_sources().len());
    println!("Number of steps: {}", new_pot.get_recipe().read().unwrap().len());

Ingredient Crates

The community can add Ingredient crates that can be used along with this crate to simplify adding ingredients for common integrations or transformations. Some sample crates include:

  • cstea: Fill/Pour integrations for csv files
  • elastictea: Fill/Pour integrations for Elasticsearch
  • logtea: Fill integration for log files


Rust based ETL inspired by "keras"




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