systemg

Systemg - A Lightweight Process Manager

Systemg is a simple, fast, and dependency-free process manager written in Rust.
It aims to provide a minimal alternative to systemd and other heavyweight service managers, focusing on ease of use, clarity, and performance.

Why Systemg?

Traditional process managers like systemd are complex, heavy, and introduce unnecessary dependencies.
Systemg offers a lightweight, configuration-driven solution that's easy to set up and maintain.

Features

• Declarative YAML Configuration - Define services, dependencies, and restart policies easily.
• Automatic Process Monitoring - Restart crashed services based on custom policies.
• Dependency-Aware Startup - Honour depends_on chains, skip unhealthy dependencies, and cascade stop dependents on failure.
• Environment Variable Support - Load variables from .env files and per-service configurations.
• Minimal & Fast - Built with Rust, designed for performance and low resource usage.
• No Root Required - Unlike systemd, it doesn't take over PID 1.

Comparison vs Alternatives

Getting Started

Installation

Install the system binary:

curl -fsSL https://sh.sysg.dev | sh

Install systemg using cargo:

cargo install sysg

Or download the pre-built binary from the releases page.

Basic Commands

The sysg command-line interface provides several subcommands for managing processes.

Start

Start the process manager with the given configuration:

# Start with default configuration file (systemg.yaml)
sysg start

# Start with a specific configuration file
sysg start --config systemg.yaml

# Start the long-lived supervisor (persists after you log out)
sysg start --config systemg.yaml --daemonize

# Subsequent commands talk to the supervisor without re-spawning it
sysg status

# Override logging verbosity for the current run (works with every subcommand; names or 0-5)
sysg start --log-level debug
sysg start --log-level 4

When the supervisor is running it remains active in the background, holding service processes in the same process group so sysg stop, sysg restart, sysg status, and sysg logs can coordinate them even after you disconnect from the shell that started them.

Stop

Stop the process manager or a specific service:

# Stop the supervisor and every managed service
sysg stop

# Stop a specific service
sysg stop --service myapp

Restart

Restart the process manager:

# Restart all services managed by the supervisor
sysg restart

# Restart with a different configuration
sysg restart --config new-config.yaml

Status

Check the status of running services:

# Show status of all services
sysg status

# Show status of a specific service
sysg status --service webserver

Logs

View logs for a specific service:

# View the last 50 lines of logs for all services
sysg logs

# View logs for a specific service
sysg logs api-service

# View a custom number of log lines
sysg logs database --lines 100

Dependency handling

Declare service relationships with the depends_on field to coordinate startup order and health checks. Systemg will:

• start services in a topologically sorted order so each dependency is running or has exited successfully before its dependents launch;
• skip dependents whose prerequisites fail to start, surfacing a clear dependency error instead of allowing a partial boot;
• stop running dependents automatically when an upstream service crashes, preventing workloads from running against unhealthy backends.

For example:

services:
  database:
    command: "postgres -D /var/lib/postgres"

  web:
    command: "python app.py"
    depends_on:
      - database

If database fails to come up, web will remain stopped and log the dependency failure until the database is healthy again.

Testing

To run the test suite:

# Run all tests
cargo test

# Run specific test
cargo test test_service_lifecycle

Build from Source

To build systemg from source:

# Clone the repository
git clone https://github.com/ra0x3/systemg.git
cd systemg

# Build the project
cargo build --release

# The binary will be available at target/release/sysg

Contributing

Contributions to systemg are welcome! Please see the CONTRIBUTING.md file for guidelines.