Implementation:Fede1024 Rust rdkafka ClientConfig Builder

Knowledge Sources	rust-rdkafka librdkafka Configuration
Domains	Messaging, Configuration
Last Updated	2026-02-07 19:00 GMT

Overview

Concrete builder for constructing Kafka client instances provided by the rust-rdkafka library.

Description

The ClientConfig struct provides a fluent builder API for Kafka client construction. It accumulates string key-value configuration parameters in a HashMap and then instantiates the desired client type through create() (default context) or create_with_context() (custom context). The builder delegates to librdkafka's native configuration system via rd_kafka_conf_new and rd_kafka_conf_set.

Usage

Import and use this struct whenever creating any Kafka client. Call new() to start, chain set() calls for parameters, then call create::<T>() with the desired client type.

Code Reference

Source Location

Repository: rust-rdkafka
File: src/config.rs
Lines: L232-316

Signature

impl ClientConfig {
    /// Creates a new empty configuration.
    pub fn new() -> ClientConfig

    /// Sets a parameter in the configuration.
    pub fn set<K, V>(&mut self, key: K, value: V) -> &mut ClientConfig
    where
        K: Into<String>,
        V: Into<String>,

    /// Uses the current configuration to create a new Consumer or Producer.
    pub fn create<T: FromClientConfig>(&self) -> KafkaResult<T>

    /// Uses the current configuration and the provided context to create a new Consumer or Producer.
    pub fn create_with_context<C, T>(&self, context: C) -> KafkaResult<T>
    where
        C: ClientContext,
        T: FromClientConfigAndContext<C>,
}

Import

use rdkafka::config::ClientConfig;

I/O Contract

Inputs

Name	Type	Required	Description
key	K: Into<String>	Yes	Kafka configuration parameter name (e.g., "bootstrap.servers")
value	V: Into<String>	Yes	Configuration parameter value
context	C: ClientContext	No	Custom context for callbacks (only for create_with_context)
T (type param)	FromClientConfig	Yes	Target client type (e.g., FutureProducer, StreamConsumer)

Outputs

Name	Type	Description
create() returns	KafkaResult<T>	Configured client instance or error
create_with_context() returns	KafkaResult<T>	Client instance with custom context or error

Usage Examples

Create a FutureProducer

use rdkafka::config::ClientConfig;
use rdkafka::producer::FutureProducer;

let producer: FutureProducer = ClientConfig::new()
    .set("bootstrap.servers", "localhost:9092")
    .set("message.timeout.ms", "5000")
    .create()
    .expect("Producer creation failed");

Create a StreamConsumer

use rdkafka::config::ClientConfig;
use rdkafka::consumer::StreamConsumer;

let consumer: StreamConsumer = ClientConfig::new()
    .set("bootstrap.servers", "localhost:9092")
    .set("group.id", "my-group")
    .set("auto.offset.reset", "earliest")
    .create()
    .expect("Consumer creation failed");

Create with Custom Context

use rdkafka::config::ClientConfig;
use rdkafka::consumer::StreamConsumer;

let consumer: StreamConsumer<CustomContext> = ClientConfig::new()
    .set("bootstrap.servers", "localhost:9092")
    .set("group.id", "my-group")
    .create_with_context(CustomContext)
    .expect("Consumer creation failed");

Related Pages

Implements Principle

Principle:Fede1024_Rust_rdkafka_Client_Configuration

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