🌀 Flint — KVM Management, Reimagined

A single <11MB binary with a modern Web UI, CLI, and API for KVM.
No XML. No bloat. Just VMs.

Flint is a modern, self-contained KVM management tool built for developers, sysadmins, and home labs who want zero bloat and maximum efficiency. It was built in a few hours out of a sudden urge for something better.

📋 Prerequisites

System Requirements:

• Linux host (Debian, Ubuntu, Fedora, RHEL, Arch, etc.)
• libvirt >= 6.10.0 (check with libvirtd --version)
• QEMU/KVM virtualization support

Required Packages:

sudo apt update
sudo apt install -y qemu-kvm libvirt-daemon-system libvirt-daemon libvirt-clients bridge-utils
sudo systemctl enable --now libvirtd

sudo dnf install -y qemu-kvm libvirt libvirt-client virt-install
sudo systemctl enable --now libvirtd

sudo pacman -S qemu-full libvirt virt-install virt-manager
sudo systemctl enable --now libvirtd

Note: If you encounter libvirt-lxc.so.0: cannot open shared object file, install the LXC library:

# Debian/Ubuntu
sudo apt install -y libvirt-daemon-driver-lxc

# RHEL/Fedora
sudo dnf install -y libvirt-daemon-lxc

# Arch
sudo pacman -S libvirt-lxc

Platform Compatibility:

Flint is built with CGO (libvirt-go bindings). We provide binaries for both glibc and musl (Alpine Linux):

• glibc binaries: flint-linux-amd64, flint-linux-arm64 (for Debian, Ubuntu, Fedora, RHEL, Arch, etc.)
• musl binaries: flint-linux-amd64-musl, flint-linux-arm64-musl (for Alpine Linux)

# For Alpine Linux (amd64)
wget https://github.com/volantvm/flint/releases/latest/download/flint-linux-amd64-musl.zip
unzip flint-linux-amd64-musl.zip
chmod +x flint
./flint serve

# For Alpine Linux (arm64)
wget https://github.com/volantvm/flint/releases/latest/download/flint-linux-arm64-musl.zip
unzip flint-linux-arm64-musl.zip
chmod +x flint
./flint serve

# Install required Alpine packages
apk add libvirt-daemon libvirt-qemu qemu-system-x86_64
rc-update add libvirtd
rc-service libvirtd start

apk add gcompat libstdc++
wget https://github.com/volantvm/flint/releases/latest/download/flint-linux-amd64.zip
unzip flint-linux-amd64.zip
chmod +x flint
./flint serve

🚀 One-Liner Install

curl -fsSL https://raw.githubusercontent.com/volantvm/flint/main/install.sh | bash

Auto-detects OS/arch, installs to /usr/local/bin, and prompts for web UI passphrase setup.

🔐 Security & Authentication

Flint implements a multi-layered security approach:

Web UI Security:

• Passphrase Authentication: Web interface requires a passphrase login
• Session-Based: Secure HTTP-only cookies with 1-hour expiry
• No API Key Exposure: Web UI never exposes API keys to browsers

API Security:

• Bearer Token Authentication: CLI and external tools use API keys
• Protected Endpoints: All API endpoints require authentication
• Flexible Access: Support for both session cookies and API keys

Authentication Flow:

# First run - set passphrase
flint serve
# 🔐 No web UI passphrase set. Let's set one up for security.
# Enter passphrase: ********

# Web UI access
# Visit http://your-server:5550 → Enter passphrase → Full access

# CLI access (uses API key)
flint vm list --all

# External API access
curl -H "Authorization: Bearer YOUR_API_KEY" http://localhost:5550/api/vms

✨ Core Philosophy

• 🖥️ Modern UI — A beautiful, responsive Next.js + Tailwind interface, fully embedded.
• ⚡ Single Binary — No containers, no XML hell. A sub-8MB binary is all you need.
• 🛠️ Powerful CLI & API — Automate everything. If you can do it in the UI, you can do it from the command line or API.
• 📦 Frictionless Provisioning — Native Cloud-Init support and a simple, snapshot-based template system.
• 🔐 Secure by Default — Multi-layered authentication with passphrase protection.
• 💪 Non-Intrusive — Flint is a tool that serves you. It's not a platform that locks you in.
• 🌐 Remote Management — Connect to remote KVM/libvirt servers via SSH from a single Flint instance.

🏎️ Quickstart

1. Start the Server

# Interactive setup (recommended for first run)
flint serve --set-passphrase

# Or set passphrase directly
flint serve --passphrase "your-secure-password"

# Or use environment variable
export FLINT_PASSPHRASE="your-secure-password"
flint serve

On first run, you'll be prompted to set a web UI passphrase for security.

• Web UI: http://localhost:5550 (requires passphrase login)
• API: http://localhost:5550/api (requires authentication)

2. Web UI Access

• Visit http://localhost:5550
• Enter your passphrase to access the management interface
• All API calls are automatically authenticated via session

3. CLI Usage

# VM Management
flint vm list                    # List all VMs
flint vm launch my-server        # Create and start a VM
flint vm ssh my-server          # SSH into a VM

# Cloud Images
flint image list                 # Browse cloud images
flint image download ubuntu-24.04 # Download an image

# Networks & Storage
flint network list               # List networks
flint storage volume list default # List storage volumes

4. API Access (for external tools)

# Get your API key (requires authentication)
curl -H "Authorization: Bearer YOUR_API_KEY" http://localhost:5550/api/vms

🌐 Remote Server Management via SSH

Flint can connect to remote KVM/libvirt servers via SSH, allowing you to manage distributed virtualization infrastructure from a single instance.

Setup Requirements:

1. SSH key-based authentication configured between Flint host and remote server
2. Remote server must have libvirt >= 6.10.0 installed
3. User on remote server must have permissions to access libvirt

Configuration Methods:

Option 1: Web UI (Recommended)

1. Navigate to Settings in the Flint web interface
2. Enable "SSH Connection" toggle
3. Fill in SSH connection details:
   • Username (e.g., root or user with libvirt permissions)
   • Host (IP address or hostname)
   • Port (default: 22)
   • SSH Key Path (auto-detected from ~/.ssh/)
4. Click "Test Connection" to verify
5. Click "Save Configuration" and restart Flint

Option 2: Configuration File Edit ~/.flint/config.json:

{
  "libvirt": {
    "uri": "qemu:///system",
    "ssh": {
      "enabled": true,
      "username": "root",
      "host": "192.168.1.100",
      "port": 22,
      "key_path": "~/.ssh/id_rsa",
      "known_hosts_path": "~/.ssh/known_hosts"
    }
  }
}

Option 3: Environment Variables

export FLINT_LIBVIRT_SSH_ENABLED=true
export FLINT_LIBVIRT_SSH_USERNAME=root
export FLINT_LIBVIRT_SSH_HOST=192.168.1.100
export FLINT_LIBVIRT_SSH_PORT=22
export FLINT_LIBVIRT_SSH_KEY_PATH=~/.ssh/id_rsa
flint serve

SSH Key Setup:

# On Flint host, generate SSH key if needed
ssh-keygen -t rsa -b 4096 -f ~/.ssh/id_rsa

# Copy public key to remote server
ssh-copy-id root@192.168.1.100

# Verify connection
ssh root@192.168.1.100 virsh list --all

Security Notes:

• SSH keys must have secure permissions (600 or 400)
• Password authentication is not supported (key-based only)
• Flint uses the standard libvirt SSH transport (qemu+ssh://)
• All libvirt operations are encrypted via SSH tunnel

📖 Full Documentation

Complete CLI commands, API reference, and advanced usage:

➡️ docs.md - Complete CLI & API Documentation

🔧 Tech Stack

• Backend: Go 1.25+
• Web UI: Next.js + Tailwind + Bun
• KVM Integration: libvirt-go
• Binary Size: ~11MB (stripped)

🚀 Flint is young, fast-moving, and designed for builders.
Try it. Break it. Star it. Contribute.

_{From the team at Chaser  ·  Run it on your own infrastructure →}