CNI Specification

The CNI specification defines the interface between container runtimes and network plugins. It specifies how runtimes invoke plugins via environment variables (CNI_COMMAND, CNI_CONTAINERID, CNI_NETNS, CNI_IFNAME, CNI_PATH, CNI_ARGS) and stdin configuration, and how plugins respond on stdout with network interface details. The spec covers ADD, DEL, CHECK, and VERSION operations for managing container network attachments, and defines the plugin chaining model used by meta-plugins.