coreos/flannel
Flannel
Flannel is a virtual networking layer and Kubernetes CNI plugin that provides automated subnet management and Layer 3 overlay connectivity. It functions as a container network fabric, enabling distributed containers and pods across multiple hosts to communicate using unique IP addresses without manual routing configuration.
The system operates as a distributed subnet manager, allocating and persisting unique subnet ranges to hosts using a distributed key-value store. This ensures conflict-free container addressing across the cluster by tracking subnet leases and persisting network metadata.
The project handles network fabric orchestration through various transport mechanisms, including VXLAN-based overlay networking and cloud-native routing. It manages traffic transport by encapsulating packets or using bridge interfaces to connect container namespaces to the cluster fabric.
Features
- Kubernetes Network Operators - Provides the primary networking layer that automates pod-to-pod connectivity across a Kubernetes cluster.
- CNI Plugins - Acts as a Kubernetes CNI plugin to assign IP addresses and enable pod-to-pod communication.
- Cross-Host Connectivity - Enables pods on different physical or virtual machines to communicate via a shared network overlay.
- Container Networking Tools - Creates a virtual network fabric that allows distributed containers to exchange traffic without manual routing.
- Distributed Subnet Management - Allocates and persists unique subnet ranges to hosts using a distributed key-value store.
- IP Address Management Systems - Implements a centralized system for tracking and allocating unique subnet ranges across the entire node fleet.
- Host-Local Allocations - Assigns unique IP ranges to each node to ensure conflict-free container addressing across the cluster.
- Network Overlays - Implements VXLAN-based encapsulation to create a virtual L2 network across disparate physical hosts.
- Subnet Lease Allocation - Assigns unique subnet ranges to individual hosts from a preconfigured space to prevent IP conflicts.
- Distributed Key-Value Stores - Integrates with distributed key-value stores to maintain a consistent source of truth for network configurations.
- Configuration Persistence - Persists subnet allocations and host metadata to ensure network state survives across restarts.
- Cluster Network Orchestration - Orchestrates cluster-wide network settings, including subnet leases and advertised node addresses.
- Pluggable Transport Layers - Provides modular interfaces to switch between VXLAN, host-gw, and cloud-native routing transport implementations.
- Traffic Tunnels - Encapsulates network data streams within UDP packets (VXLAN) to enable connectivity between hosts.
- Virtual Network Bridging - Connects container network namespaces to virtual bridges for forwarding traffic to the cluster fabric.
- Networking and Discovery - Etcd-backed network fabric for container clusters.
- Networking And Proxies - Virtual networking for container subnets.
- Networking & Connectivity - Network fabric for Kubernetes containers.
Star history
How this analysis was created: This summary and feature list were written by an AI model that read the project's README and public documentation pages. Each feature links to the documentation it came from; stars, license and language come straight from the GitHub API. The model does not read the source code, and the analysis is refreshed when the project is re-analysed. Learn more on our About page.
