Environment Variables

HDDS can be configured via environment variables. All variables are prefixed with HDDS_.

Discovery & Networking

Variable	Purpose	Example
HDDS_SPDP_UNICAST_PEERS	Manual unicast peer list	192.168.1.100:7400,192.168.1.101:7400
HDDS_LOG_UDP	Enable UDP debug logging	1
HDDS_INTEROP_DIAGNOSTICS	Enable interop diagnostics	1
HDDS_FORCE_DATA_MC	Route DATA to multicast	1
HDDS_DISABLE_TYPE_OBJECT	Disable TypeObject announcement	1

Network Interface Control

Variable	Purpose	Format
HDDS_MULTICAST_IF	Force multicast interface	IPv4 address (e.g., 192.168.1.5)
HDDS_UNICAST_IF	Force unicast interface	IPv4 address
HDDS_INTERFACE_ALLOW	Allow specific interfaces	CIDR list: eth0,192.168.1.0/24

TTL (Time-To-Live) Configuration

Variable	Purpose	Range
HDDS_TTL	Set both multicast & unicast TTL	1-255
HDDS_MULTICAST_TTL	Multicast TTL only	1-255
HDDS_UNICAST_TTL	Unicast TTL only	1-255

Source Filtering

Variable	Purpose	Format
HDDS_SOURCE_ALLOW	Allowed source CIDRs	192.168.1.0/24,10.0.0.0/8
HDDS_SOURCE_DENY	Denied source CIDRs	192.168.0.0/16

QoS & Traffic Control

Variable	Purpose	Format
HDDS_DSCP	DSCP code points	18,46,26 (AF21, EF, AF31)

Observability

Variable	Purpose	Values
HDDS_EXPORTER_DISABLE	Disable telemetry export	1, true, or yes

Logging

Standard Rust logging via RUST_LOG:

# Enable debug logging for HDDS
RUST_LOG=hdds=debug ./my_app

# Trace-level for discovery
RUST_LOG=hdds::discovery=trace ./my_app

# Multiple filters
RUST_LOG=hdds=debug,hdds::transport=trace ./my_app

Examples

Static Peer Discovery

# Disable multicast, use unicast peers only
export HDDS_SPDP_UNICAST_PEERS="10.0.0.1:7400,10.0.0.2:7400"
./my_dds_app

Network Interface Selection

# Force specific network interface
export HDDS_MULTICAST_IF="192.168.1.100"
export HDDS_UNICAST_IF="192.168.1.100"
./my_dds_app

TTL for Multi-Hop Networks

# Increase TTL for WAN scenarios
export HDDS_TTL=32
./my_dds_app

Debug Interoperability

# Enable verbose interop logging
export HDDS_INTEROP_DIAGNOSTICS=1
export RUST_LOG=hdds=debug
./my_dds_app

Firewall-Friendly Setup

# Disable multicast, use unicast only
export HDDS_SPDP_UNICAST_PEERS="peer1.example.com:7400"
export HDDS_FORCE_DATA_MC=0
./my_dds_app