Flatcar Container Linux is an immutable Linux distribution focused on secure, minimal, and auto-updating hosts for container workloads. It is commonly used for Kubernetes nodes and clustered infrastructure where consistent host state and controlled updates are critical.
- Immutable base OS: Core system is designed to be read-only and managed as an image-style platform.
- Automatic updates: Update engine supports unattended updates and coordinated reboot behavior.
- Container-first design: Optimized for Docker, containerd, and Kubernetes environments.
- Minimal attack surface: Small footprint with fewer mutable components.
- Cloud and bare-metal support: Used across cloud providers, virtualization platforms, and on-prem systems.
- Channel-based releases: Uses channels such as
stable, beta, and alpha.
- Rolling delivery inside channels: Updates are continuously delivered to each channel.
- Current Stable: Flatcar 3855.2.0 (March 2026)
- Safe rollout workflows: Designed for staged deployments and controlled reboot windows.
- Kubernetes worker nodes in production clusters
- Immutable server baselines for compliance and reproducibility
- Edge and appliance systems that need atomic updates and rollback-friendly operations