Samsa

Rust-native Kafka/Redpanda protocol and client implementation.

This crate provides Rust native consumers and producers as well as low level bindings for the Apache Kafka protocol. Unlike crates that use librdkafka in an FFI, users of this crate will not need the C lib and will benefit from Rust all the way down; meaning memory safety, safe concurrency, low resource usage, and of course blazing speed.

Documentation

Goals

• Easy to understand code
• Leverage best in class libraries such as Tokio, Nom to do the heavy lifting
• Start with a robust foundation and add more advanced features over time
• Provide a pure rust implementation of the Kafka protocol
• Be a good building block for future works based around Kafka

Table of contents

• Getting started
  • Producer
  • Consumer
  • Consumer group
  • TLS support
  • Compression support
  • SASL support
• Examples
• Development setup
  • Tests
• Benchmarks
• Resources

Getting started

Install samsa to your rust project with cargo add samsa or include the following snippet in your Cargo.toml dependencies:

samsa = "0.1"

This project includes Docker Compose files to help set up Redpanda and Kafka clusters to ease with testing. The easiest way to do this is to run docker-compose up to spin up a 2 broker Redpanda cluster. If you want to use different versions of Kafka, check out the DockerCompose.README.md

Producer

A producer sends messages to the given topic and partition.

It is buffered, with both a timeout and volume threshold that clears the buffer when reached. This is how letency and throughout can be tweaked to achieve the desired rates.

To instantiate one, it is easiest to use a Stream and the ProducerBuilder.

use samsa::prelude::*;

let bootstrap_addrs = vec![BrokerAddress {
        host: "127.0.0.1".to_owned(),
        port: 9092,
    }];
let topic_name = "my-topic".to_string();
let partition_id = 0;

// create a stream of 5k messages in batches of 100
let stream = iter(0..5000).map(|_| ProduceMessage {
    topic: topic_name.to_string(),
    partition_id,
    key: Some(bytes::Bytes::from_static(b"Tester")),
    value: Some(bytes::Bytes::from_static(b"Value")),
    headers: vec![
        samsa::prelude::Header::new(String::from("Key"), bytes::Bytes::from("Value"))
    ],
}).chunks(100);

let output_stream =
ProducerBuilder::<TcpConnection>::new(bootstrap_addrs, vec![topic_name.to_string()])
    .await?
    .batch_timeout_ms(100)
    .max_batch_size(100)
    .clone()
    .build_from_stream(stream)
    .await;

tokio::pin!(output_stream);
while (output_stream.next().await).is_some() {}

Consumer

A Consumer is used to fetch messages from the broker. It is an asynchronous iterator that can be configured to auto-commit. To instantiate one, start with a ConsumerBuilder.

use samsa::prelude::*;

let bootstrap_addrs = vec![BrokerAddress {
        host: "127.0.0.1".to_owned(),
        port: 9092,
    }];
let partitions = vec![0];
let topic_name = "my-topic".to_string();
let assignment = TopicPartitionsBuilder::new()
    .assign(topic_name, partitions)
    .build();

let consumer = ConsumerBuilder::<TcpConnection>::new(
        bootstrap_addrs,
        assignment,
    )
    .await?
    .build();

let stream = consumer.into_stream();
// have to pin streams before iterating
tokio::pin!(stream);

// Stream will do nothing unless consumed.
while let Some(Ok((batch, offsets))) = stream.next().await {
    println!("{:?}", batch);
}

Consumer group

You can set up a consumer group with a group id and assignment. The offsets are commit automatically for the member of the group.

use samsa::prelude::*;

let bootstrap_addrs = vec![BrokerAddress {
        host: "127.0.0.1".to_owned(),
        port: 9092,
    }];
let partitions = vec![0];
let topic_name = "my-topic".to_string();
let assignment = TopicPartitionsBuilder::new()
    .assign(topic_name, partitions)
    .build();
let group_id = "The Data Engineering Team".to_string();

let consumer_group_member = ConsumerGroupBuilder::<TcpConnection>::new(
        bootstrap_addrs,
        group_id,
        assignment,
    ).await?
    .build()
    .await?;

let stream = consumer_group_member.into_stream();
// have to pin streams before iterating
tokio::pin!(stream);
 
// Stream will do nothing unless consumed.
while let Some(batch) = stream.next().await {
    println!("{:?}", batch);
}

TLS support

You can add TLS support to your consumer or producer for secured communication. To enable this, start with specifying the TlsConnectionOptions, and pass it into an instance of the ProducerBuilder or ConsumerBuilder.

Example for Producer with TLS support:

use samsa::prelude::*;

let tls_option = TlsConnectionOptions {
        broker_options: vec![BrokerAddress {
          host: "127.0.0.1".to_owned(),
          port: 9092,
        }],
        key: "/path_to_key_file".into(),
        cert: "/path_to_cert_file".into(),
        cafile: Some("/path_to_ca_file".into()),
    };
let topic_name = "my-topic".to_string();
let partition_id = 0;

let message = ProduceMessage {
        topic: topic_name.to_string(),
        partition_id,
        key: Some(bytes::Bytes::from_static(b"Tester")),
        value: Some(bytes::Bytes::from_static(b"Value")),
        headers: vec![
            Header::new(String::from("Key"), bytes::Bytes::from("Value"))
        ],
    };

let producer_client = ProducerBuilder::<TlsConnection>::new(
        tls_option, 
        vec![topic_name.to_string()]
    )
    .await?
    .batch_timeout_ms(1)
    .max_batch_size(2)
    .clone()
    .build()
    .await;

producer_client
    .produce(message)
    .await;

Example for Consumer with TLS support:

use samsa::prelude::*;

let tls_option = TlsConnectionOptions {
        broker_options: vec![BrokerAddress {
            host: "127.0.0.1".to_owned(),
            port: 9092,
        }],
        key: "/path_to_key_file".into(),
        cert: "/path_to_cert_file".into(),
        cafile: Some("/path_to_ca_file".into()),
    };
let partitions = vec![0];
let topic_name = "my-topic".to_string();
let assignment = TopicPartitionsBuilder::new()
    .assign(topic_name, partitions)
    .build();

let consumer = ConsumerBuilder::<TlsConnection>::new(
        tls_option,
        assignment,
    )
    .await?
    .build();

let stream = consumer.into_stream();
// have to pin streams before iterating
tokio::pin!(stream);

// Stream will do nothing unless consumed.
while let Some(batch) = stream.next().await {
    println!("{:?} messages read", batch.unwrap().count());
}

Compression support

We provide support for compression in the producer using the Compression enum. The enum allows to specify what type of compression to use. The Consumer will automatically know to decompress the message.

Example for Producer with TLS and GZIP compression support:

use samsa::prelude::*;

let tls_option = TlsConnectionOptions {
        broker_options: vec![BrokerAddress {
            host: "127.0.0.1".to_owned(),
            port: 9092,
        }],
        key: "/path_to_key_file".into(),
        cert: "/path_to_cert_file".into(),
        cafile: Some("/path_to_ca_file".into()),
    };
let topic_name = "my-topic".to_string();
let partition_id = 0;

let message = ProduceMessage {
        topic: topic_name.to_string(),
        partition_id,
        key: Some(bytes::Bytes::from_static(b"Tester")),
        value: Some(bytes::Bytes::from_static(b"Value")),
        headers: vec![
            Header::new(String::from("Key"), bytes::Bytes::from("Value"))
        ],
    };

let producer_client = ProducerBuilder::new(tls_option, vec![topic_name.to_string()])
    .await?
    .compression(Compression::Gzip)
    .batch_timeout_ms(1)
    .max_batch_size(2)
    .clone()
    .build()
    .await;

producer_client
    .produce(message)
    .await;

SASL support

We include support for SASL using all typical mechanisms: PLAIN, SCRAM-SHA-256, SCRAM-SHA-512. This is represented as another type of BrokerConnection that our Consumers and Producers recieve as a generic parameter. All that is needed is to provide the credentials.

Example for Producer using both TLS and SASL:

use samsa::prelude::*;

let tls_config = TlsConnectionOptions {
    broker_options: vec![BrokerAddress {
        host: "127.0.0.1".to_owned(),
        port: 9092,
    }],
    key: "/path_to_key_file".into(),
    cert: "/path_to_cert_file".into(),
    cafile: Some("/path_to_ca_file".into()),
};

let sasl_config = SaslConfig::new(String::from("myuser"), String::from("pass1234"), None, None);

let options = SaslTlsConfig {
    tls_config,
    sasl_config,
};

let topic_name = "atopic";

let s = ConsumerBuilder::<SaslTlsConnection>::new(
    options,
    TopicPartitionsBuilder::new()
        .assign(topic_name.to_owned(), vec![0])
        .build(),
)
.await
.unwrap()
.build()
.into_stream();

tokio::pin!(s);

while let Some(m) = s.next().await {
    tracing::info!("{:?} messages read", m.unwrap().count());
}

Examples

We provide high level examples for those interested in trying samsa out. The setup is as follows:

1. Use docker-compose up to start your redpanda cluster.
2. Go to http://localhost:8080/topics to view the redpanda console.
3. Create a topic named my-topic with 4 partitions.

Producer

This one is good to run first to fill up your topic with data.

1. Run cargo run --example producer
2. Visit http://localhost:8080/topics/my-topic to see data flowing in!

Consumer

Consume the messages in your topic.

1. Run cargo run --example consumer
2. Observe all the torrent of data in your terminal

ConsumerGroup

Coordinate a group of 4 consumers. This one is throttled to see the group rebalancing.

1. Run cargo run --example consumer_group
2. Visit http://localhost:8080/groups/Squad to see the lone member.
3. In another terminal window, run cargo run --example consumer_group
4. Visit the console to see the new member join.
5. Repeat 2 more times to see the full group.

TLS

We have a replica of the Producer and Consumer examples that utilize the TLS support. You will need a Cluster running with TLS enabled and the correct certificates in this codebase.

1. Set up a cluster that uses the correct TLS configuration
2. Copy your certs into the project
3. Update the paths in the following examples to be correct
4. Run cargo run --example tls_produce
5. Run cargo run --example tls_consume

SASL

We have a replica of the Producer and Consumer examples that utilize the SASL support. You will need a Cluster running with SASL enabled.

1. Set up a cluster that uses the correct SASL configuration
2. Update the credentials in the following examples to be correct
3. Run cargo run --example sasl
4. Run cargo run --example sasl_tls

Development setup

To set up the development environment, you will need the Rust Toolchain and Docker.

• Run docker-compose up to spin up a Redpanda cluster.

Tests

To run the tests, be sure to have the cluster running. Run KAFKA_BROKERS=[your cluster url] cargo test --tests --all-features -- --show-output --test-threads=1

Benchmarks

We provide a way to benchmark the library's performance through Criterion. This requires a small amount of setup:

1. Set up a local redpanda cluster
2. Create a topic with 1 partition named benchmark
3. Run the producer example using cargo run --example producer to put data in that topic
4. Run cargo bench

Results

On a 2020 Macbook Pro, 2 GHz Quad-Core Intel Core i5, 16 GB 3733 MHz LPDDR4X

Produce 1 million 10 byte messages

time:   [1.5852 s 1.6119 s 1.6406 s]

Consume 1 million 10 byte messages

time:   [1.8013 s 1.8112 s 1.8225 s]

Resources

• Kafka Protocol Spec
• Confluence Docs