Crate tonic_lb_k8s 

Tonic client load balancing for Kubernetes.

This crate watches Kubernetes EndpointSlice resources and feeds endpoint changes to a Tonic balance channel, enabling client-side load balancing across pod replicas.

Why?

Standard Kubernetes ClusterIP services don’t load balance gRPC effectively. HTTP/2 multiplexes all requests over a single long-lived TCP connection, so all traffic goes to one pod. This crate handles endpoint discovery and connection management automatically.

Usage

use std::net::SocketAddr;
use std::time::Duration;
use tonic::transport::{Channel, Endpoint};
use tonic_lb_k8s::{discover, DiscoveryConfig};

// Create your own balance channel
let (channel, tx) = Channel::balance_channel::<SocketAddr>(1024);

// Start discovery - build function returns Endpoint for each address
let config = DiscoveryConfig::new("my-grpc-service", 50051);
discover(config, tx, |addr| {
    Endpoint::from_shared(format!("http://{addr}"))
        .unwrap()
        .connect_timeout(Duration::from_secs(5))
});

// Use with your generated gRPC client
// let client = MyServiceClient::new(channel);

Structs

DiscoveryConfig

Configuration for Kubernetes endpoint discovery.

Enums

Port

Port specification for the gRPC service.

Functions

discover

Starts watching Kubernetes endpoints and sends changes to the provided sender.