rusmes-config

Configuration management for RusMES. Loads and validates TOML and YAML configuration files, providing strongly-typed config structs to all server components. Supports environment variable overrides, hot-reload on SIGHUP, and structured validation with descriptive errors.

Status

Complete. Supports loading ServerConfig from both TOML and YAML files with all major configuration sections. Environment variable overrides, hot-reload, log rotation, and validation are all production-ready.

Configuration Structs

Storage Backend Variants

pub enum StorageConfig {
    Filesystem { path: String },
    Postgres { connection_string: String },
    AmateRS { endpoints: Vec<String>, replication_factor: usize },
}

Environment Variable Overrides

All major settings can be overridden at runtime via RUSMES_* environment variables (30+ supported). Examples:

RUSMES_SMTP_PORT=2525
RUSMES_SMTP_HOST=0.0.0.0
RUSMES_IMAP_PORT=143
RUSMES_DOMAIN=mail.example.com
RUSMES_STORAGE_BACKEND=postgres
RUSMES_STORAGE_PATH=/var/mail
RUSMES_LOG_LEVEL=debug
RUSMES_METRICS_PORT=9090

Environment variables take precedence over file-based configuration values.

Hot-Reload

The server reloads configuration on SIGHUP without restarting. Config structs are re-parsed from the same file path and validated before replacing the live configuration. If validation fails, the reload is aborted and the server continues with the previous configuration.

Validation

ServerConfig::from_file() validates all fields on load and returns descriptive errors:

• Domain and postmaster address format
• Port ranges (1-65535)
• File paths (existence checks where applicable)
• Processor name uniqueness
• Auth backend required fields (e.g., LDAP URL, SQL DSN, OAuth2 client ID/secret)

Size and Duration Parsers

// Size strings
"50MB"   -> 52_428_800 bytes
"1GB"    -> 1_073_741_824 bytes
"1024KB" -> 1_048_576 bytes
"1024"   -> 1024 bytes (bare integer = bytes)

// Duration strings
"60s"  -> 60 seconds
"30m"  -> 1800 seconds
"1h"   -> 3600 seconds

Log Rotation

[log]
level = "info"
format = "json"          # "json" | "text"

[log.rotation]
policy = "daily"         # "daily" | "hourly" | "size"
max_size_bytes = 104857600  # used when policy = "size"
keep_files = 7

Usage

use rusmes_config::ServerConfig;

// Load TOML configuration
let config = ServerConfig::from_file("rusmes.toml")?;
println!("Domain: {}", config.domain);
println!("SMTP port: {}", config.smtp.port);
println!("Max message size: {} bytes", config.smtp.max_message_size_bytes()?);

// Load YAML configuration
let config = ServerConfig::from_file("rusmes.yaml")?;
// ... same API

The format is auto-detected based on file extension:

• .toml files are parsed as TOML
• .yaml or .yml files are parsed as YAML

Example Configuration

See examples/ directory for minimal, full reference, and production configurations in both TOML and YAML formats:

• rusmes-minimal.toml / rusmes-minimal.yaml
• rusmes-full.toml / rusmes-full.yaml
• rusmes-production.toml

Dependencies

• rusmes-proto - MailAddress type
• serde - deserialization
• toml - TOML parsing
• serde_yaml - YAML parsing
• anyhow - error handling

Tests

cargo nextest run -p rusmes-config --all-features

57 tests run: 57 passed, 0 skipped.

Tests cover: size string parsing, duration string parsing, log config (rotation policy, level parsing, module-level filters), TOML configuration deserialization for all sections (Auth, Queue, Security, Metrics, Logging, Rate Limits), YAML configuration deserialization, TOML/YAML equivalence, and field validation (domain, email, port).