Mastering Kubernetes - Second Edition

CNI plugin

The CNI plugin's job is to add a network interface into the container network namespace and bridge the container to the host via a veth pair. It should then assign an IP address through an IPAM (IP address management) plugin and set up routes.

The container runtime (Docker, rkt, or any other CRI-compliant runtime) invokes the CNI plugin as an executable. The plugin needs to support the following operations:

• Add a container to the network
• Remove a container from the network
• Report version

The plugin uses a simple command-line interface, standard input/output, and environment variables. The network configuration in JSON format is passed to the plugin through standard input. The other arguments are defined as environment variables: ...