Configuration Options

ros-z provides multiple ways to configure Zenoh, from simple to advanced.

Option 1: Default Configuration (Recommended)

Use the built-in ROS session config for standard deployments:

let ctx = ZContextBuilder::default().build()?;

What it does:

• Connects to router at tcp/localhost:7447
• Uses ROS-compatible timeouts and buffer sizes
• Disables multicast discovery (uses router instead)

Option 2: Custom Router Endpoint

Connect to a router on a different host or port:

let ctx = ZContextBuilder::default()
    .with_router_endpoint("tcp/192.168.1.100:7447")
    .build()?;

Use cases:

• Distributed systems with remote router
• Custom port configurations
• Multiple isolated networks

Option 3: Config File via Environment Variable

Point to a JSON5 config file without changing code, using the same variable as rmw_zenoh_cpp:

export ZENOH_SESSION_CONFIG_URI=/path/to/session_config.json5

// No code changes needed - the config file is loaded automatically
let ctx = ZContextBuilder::default().build()?;

Option 4: Environment Variable Overrides

Override individual Zenoh configuration settings using the ZENOH_CONFIG_OVERRIDE environment variable, using the same variable as rmw_zenoh_cpp:

# Override mode and endpoint
export ZENOH_CONFIG_OVERRIDE='mode="client";connect/endpoints=["tcp/192.168.1.100:7447"]'

# Run any ros-z application — overrides apply automatically
cargo run --example z_pubsub

// No code changes needed - overrides are applied automatically
let ctx = ZContextBuilder::default().build()?;

Format:

• Semicolon-separated key=value pairs
• Values use JSON5 syntax
• Keys use slash-separated paths (e.g., connect/endpoints, scouting/multicast/enabled)

Common examples:

# Connect to remote router
export ZENOH_CONFIG_OVERRIDE='connect/endpoints=["tcp/10.0.0.5:7447"]'

# Enable multicast scouting explicitly
export ZENOH_CONFIG_OVERRIDE='scouting/multicast/enabled=true'

# Multiple overrides
export ZENOH_CONFIG_OVERRIDE='mode="client";connect/timeout_ms=5000;scouting/multicast/enabled=false'

Option 5: Advanced Configuration Builders

Fine-tune session or router settings programmatically:

use ros_z::config::{SessionConfigBuilder, RouterConfigBuilder};

// Customize session config
let session_config = SessionConfigBuilder::new()
    .with_router_endpoint("tcp/192.168.1.100:7447")
    .build()?;

let ctx = ZContextBuilder::default()
    .with_zenoh_config(session_config)
    .build()?;

// Or build a custom router config
let router_config = RouterConfigBuilder::new()
    .with_listen_port(7448)  // Custom port
    .build()?;

zenoh::open(router_config).await?;

Key builder methods:

Option 6: Peer Mode Using Multicast Discovery (No Router Required)

Revert to multicast peer discovery for simple setups:

// Use vanilla Zenoh config (peer mode with multicast)
let ctx = ZContextBuilder::default()
    .with_zenoh_config(zenoh::Config::default())
    .build()?;

Option 7: Load from Config File (Programmatic)

Use JSON5 config files for complex deployments:

let ctx = ZContextBuilder::default()
    .with_config_file("/etc/zenoh/session_config.json5")
    .build()?;

When to use:

• Deploying across multiple machines
• Environment-specific configurations
• Version-controlled infrastructure