Configuration

rLightning can be configured through TOML configuration files, command-line arguments, and environment variables. Settings are resolved in the following priority order:

Command-line arguments (highest priority)
Environment variables
Configuration file
Default values (lowest priority)

TOML Configuration File

By default, rLightning looks for config/default.toml. You can specify a custom path with --config.

Full Example

[server]
host = "127.0.0.1"
port = 6379
workers = 4  # 0 = auto-detect based on CPU cores

[storage]
max_memory_mb = 0          # 0 = unlimited
eviction_policy = "noeviction"
default_ttl_seconds = 0    # 0 = no expiration

[storage.key_constraints]
max_key_size = 512             # bytes
max_value_size = 536870912     # 512 MB

[security]
require_auth = false
password = ""

[logging]
level = "info"    # trace, debug, info, warn, error
file = ""         # empty = stdout

Server Section

Setting	Default	Description
`host`	`"127.0.0.1"`	Bind address for incoming connections
`port`	`6379`	TCP port to listen on
`workers`	`4`	Number of worker threads (`0` = auto-detect CPUs)

Storage Section

Setting	Default	Description
`max_memory_mb`	`0`	Maximum memory in MB (`0` = unlimited)
`eviction_policy`	`"noeviction"`	Policy when memory limit is reached
`default_ttl_seconds`	`0`	Default TTL for new keys (`0` = none)

Available eviction policies:

noeviction — Return errors when memory limit is reached
allkeys-lru — Evict least recently used keys
allkeys-random — Evict random keys
volatile-lru — Evict least recently used keys with an expiration set
volatile-random — Evict random keys with an expiration set
volatile-ttl — Evict keys with the shortest remaining TTL

Key Constraints

Setting	Default	Description
`max_key_size`	`512`	Maximum key size in bytes
`max_value_size`	`536870912`	Maximum value size in bytes (512 MB)

Security Section

Setting	Default	Description
`require_auth`	`false`	Whether clients must authenticate
`password`	`""`	Password for AUTH command

When require_auth is true, clients must issue AUTH <password> (or AUTH <username> <password> when using ACLs) before executing any other commands.

Logging Section

Setting	Default	Description
`level`	`"info"`	Log level: `trace`, `debug`, `info`, `warn`, `error`
`file`	`""`	Log file path (empty string = log to stdout)

Command-Line Arguments

Command-line arguments override all other configuration sources.

# Specify a config file
cargo run --release -- --config path/to/config.toml

# Override individual settings
cargo run --release -- --port 6380
cargo run --release -- --bind 0.0.0.0
cargo run --release -- --max-memory-mb 512
cargo run --release -- --password mysecretpassword

# Combine multiple arguments
cargo run --release -- --port 6380 --bind 0.0.0.0 --max-memory-mb 1024 --password secret

Argument	Description
`--config`	Path to TOML configuration file
`--port`	TCP port to listen on
`--bind`	Bind address
`--max-memory-mb`	Maximum memory limit in MB
`--password`	Authentication password

Environment Variables

Environment variables use the RLIGHTNING_ prefix followed by the uppercase setting name. They override config file values but are overridden by command-line arguments.

# Examples
export RLIGHTNING_PORT=6380
export RLIGHTNING_HOST=0.0.0.0
export RLIGHTNING_MAX_MEMORY_MB=1024
export RLIGHTNING_PASSWORD=mysecretpassword
export RLIGHTNING_LOG_LEVEL=debug

# Run with environment variable configuration
RLIGHTNING_PORT=6380 RLIGHTNING_PASSWORD=secret cargo run --release

Configuration Examples

Development Setup

[server]
host = "127.0.0.1"
port = 6379
workers = 0

[storage]
max_memory_mb = 0
eviction_policy = "noeviction"

[security]
require_auth = false

[logging]
level = "debug"

Production Setup

[server]
host = "0.0.0.0"
port = 6379
workers = 0

[storage]
max_memory_mb = 4096
eviction_policy = "allkeys-lru"

[storage.key_constraints]
max_key_size = 512
max_value_size = 536870912

[security]
require_auth = true
password = "your-strong-password-here"

[logging]
level = "warn"
file = "/var/log/rlightning/server.log"

Memory-Constrained Environment

[server]
host = "127.0.0.1"
port = 6379
workers = 2

[storage]
max_memory_mb = 256
eviction_policy = "volatile-lru"
default_ttl_seconds = 3600

[security]
require_auth = true
password = "secret"

[logging]
level = "info"