Weave Net

Definition

Weave Net is a container networking solution that creates a virtual network connecting Docker containers or Kubernetes pods across multiple hosts, automatically handling encryption, addressing, and simple network policy without requiring external coordination services. It functions as a mesh overlay network, with each host running a lightweight router that discovers peers and routes container traffic directly between them, without depending on an external key-value store for coordination.

Overview

Weave Net was developed by Weaveworks to make multi-host container networking straightforward at a time when connecting containers across separate machines typically required manually configuring bridges, routes, or external service discovery systems. The problem it targets is giving containers a flat, addressable network that spans hosts without administrators having to hand-configure networking infrastructure for every new node added to a cluster. Mechanically, Weave Net runs a lightweight router as a container or process on each host, and these routers form a mesh network with their peers, exchanging topology information so that any container can reach any other container's address regardless of which host it runs on. Traffic between hosts can be encrypted using a shared network password, and Weave Net can automatically choose between a faster, kernel-based fast data path and a slower, more compatible user-space path depending on what the underlying network and kernel support. Weave Net also includes a simple built-in DNS mechanism that lets containers discover each other by name rather than requiring a separate service discovery system. Compared to Flannel, Weave Net historically offered more built-in features out of the box, including encryption and basic network policy support, without requiring integration with an external key-value store, since its mesh routers exchange state directly with each other. Compared to Calico or Cilium, Weave Net's policy capabilities have generally been simpler and less central to its design, with its main value proposition being ease of setup and a self-contained mesh architecture rather than deep, identity-aware policy enforcement. In practice, Weave Net has been used in Docker Swarm and Kubernetes clusters where operators wanted straightforward multi-host networking with minimal external dependencies, particularly in smaller or on-premises deployments where setting up BGP peering or a dedicated policy engine was seen as unnecessary complexity. Its automatic peer discovery and encryption made it attractive for teams that wanted secure, functioning cross-host networking without extensive up-front configuration. The trade-offs involve the broader shift in the Kubernetes networking ecosystem toward eBPF-based data planes and richer policy engines offered by projects like Cilium and Calico, which has reduced Weave Net's relative prominence for large-scale or security-sensitive deployments. Its mesh gossip protocol can also face scaling considerations in very large clusters compared to routing-based approaches, making it a better fit for small to medium deployments than for the largest Kubernetes environments. Teams evaluating it today often weigh its simplicity against the richer observability and policy tooling that newer eBPF-based projects now provide out of the box.

Key Features

• Forms a mesh overlay network of routers across hosts
• Automatically discovers peer nodes without external coordination services
• Encrypts inter-host traffic using a shared network password
• Includes a built-in DNS mechanism for container name discovery
• Supports both kernel fast data path and user-space networking modes
• Provides basic network policy support alongside connectivity
• Works across Docker Swarm and Kubernetes environments
• Requires minimal external infrastructure to operate

Use Cases

Alternatives

Frequently Asked Questions

Related in DevOps