Installing a Pod Network

Prior to initializing the Kubernetes cluster, the network must be considered and IP conflicts avoided. There are several Pod networking choices, in varying levels of development and feature set.

Many of the projects will mention the Container Network Interface (CNI), which is a CNCF project. Several container runtimes currently use CNI. As a standard to handle deployment management and cleanup of network resources, CNI will become more popular.

Pod Networking Choices

Calico

A flat Layer 3 network which communicates without IP encapsulation, used in production with software such as Kubernetes, OpenShift, Docker, Mesos and OpenStack. Viewed as a simple and flexible networking model, it scales well for large environments. Another network option, Canal, also part of this project, allows for integration with Flannel. Allows for implementation of network policies.

For more details, check out the Project Calico web page.

Flannel

A Layer 3 IPv4 network between the nodes of a cluster. Developed by CoreOS, it has a long history with Kubernetes. Focused on traffic between hosts, not how containers configure local networking, it can use one of several backend mechanisms, such as VXLAN. A flanneld agent on each node allocates subnet leases for the host. While it can be configured after deployment, it is much easier prior to any Pods being added.

You can learn more about Flannel from their GitHub pages.

Kube-Router

Feature-filled single binary which claims to "do it all". The project is in the alpha stage, but promises to offer a distributed load balancer, firewall, and router purposely built for Kubernetes.

For more details, check out the Kube-Router web page.

Romana

This is another project aimed at network and security automation for cloud native applications. Aimed at large clusters, IPAM-aware topology and integration with kops clusters.

To learn more, check out the Romana GitHub web page.

Weave Net

It is typically used as an add-on for a CNI-enabled Kubernetes cluster.

To learn more, check out the Weave Net web page.