Container Network Interface (CNI)

aid: cni
name: Container Network Interface (CNI)
kind: opensource
description: CNI (Container Network Interface) is a CNCF-incubating project that defines a specification and libraries for
  configuring network interfaces in Linux containers. It provides a simple exec/stdin interface between the container runtime
  and network implementation plugins, enabling pluggable networking for Kubernetes and other container orchestrators. The
  CNI spec defines four operations (ADD, DEL, CHECK, VERSION), a network configuration document format, and a plugin Result
  document. CNI also publishes a collection of reference plugins (bridge, ipvlan, macvlan, host-device, ptp, loopback) and
  meta-plugins (portmap, bandwidth, firewall, sbr).
url: https://www.cni.dev
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
tags:
- Cloud Native
- Containers
- Incubating
- Kubernetes
- Networking
- Plugins
created: '2026-03-16'
modified: '2026-04-23'
specificationVersion: '0.19'
type: Index
apis:
- aid: cni:cni-spec
  name: CNI Specification
  description: 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.
  humanURL: https://www.cni.dev/docs/spec/
  properties:
  - type: Documentation
    url: https://www.cni.dev/docs/spec/
  - type: GitHubRepository
    url: https://github.com/containernetworking/cni
  - type: JSONSchema
    url: json-schema/cni-network-config-schema.json
  - type: JSONSchema
    url: json-schema/cni-result-schema.json
  - type: JSONLDContext
    url: json-ld/cni-context.jsonld
  tags:
  - Network Plugins
  - Specification
  x-features:
  - name: ADD operation
    description: Attach a container to a network and return a Result document with assigned interfaces, IPs, routes, and DNS.
  - name: DEL operation
    description: Detach a container from a network and tear down allocated resources.
  - name: CHECK operation
    description: Verify the container's current attachment matches the prior ADD result.
  - name: VERSION operation
    description: Report the CNI spec versions a plugin supports.
  - name: Plugin Chaining
    description: Meta-plugin chaining model where a chain shares previous Result via prevResult.
  - name: Network Config Schema
    description: Schema for the JSON document that describes a network and its plugin chain.
  - name: Result Schema
    description: Schema for the Result document that plugins emit on stdout.
  x-useCases:
  - name: Kubernetes CNI Plugin
    description: Implement a CNI plugin that integrates with Kubernetes / containerd / CRI-O.
  - name: Network Validation
    description: Validate network configurations and plugin Result documents against the spec.
  - name: Custom SDN
    description: Build custom software-defined networks for containers using a portable plugin contract.
- aid: cni:cni-plugins
  name: CNI Reference Plugins
  description: A collection of reference and example networking plugins maintained by the containernetworking team that implement
    the CNI specification. Includes main plugins such as bridge, ipvlan, macvlan, ptp, host-device, and loopback, as well
    as meta plugins such as portmap, bandwidth, firewall, sbr, and tuning for additional networking functionality.
  humanURL: https://www.cni.dev/plugins/current/
  properties:
  - type: Documentation
    url: https://www.cni.dev/plugins/current/
  - type: GitHubRepository
    url: https://github.com/containernetworking/plugins
  tags:
  - Containers
  - Kubernetes
  - Linux
  - Network Plugins
  - Networking
  x-features:
  - name: bridge
    description: Linux-bridge plugin attaching container veth pairs to a bridge.
  - name: ipvlan
    description: IPVLAN plugin for L2/L3 IPVLAN attachments.
  - name: macvlan
    description: MACVLAN plugin for MACVLAN attachments.
  - name: host-device
    description: Plugin that moves an existing host device into a container netns.
  - name: ptp
    description: Point-to-point veth-pair plugin.
  - name: loopback
    description: Loopback interface configuration.
  - name: portmap
    description: Meta-plugin that publishes container ports to the host via NAT.
  - name: bandwidth
    description: Meta-plugin that applies ingress/egress traffic shaping with tc.
  - name: firewall
    description: Meta-plugin that applies iptables/nftables rules for a container.
  - name: sbr
    description: Source-based routing meta-plugin.
  x-useCases:
  - name: Kubernetes Pod Networking
    description: Use bridge + portmap as a minimal Kubernetes pod networking stack.
  - name: Multi-Network Pods
    description: Combine reference plugins via Multus or chains for multi-NIC pods.
common:
- type: Website
  url: https://www.cni.dev/
- type: Documentation
  url: https://www.cni.dev/docs/
- type: GitHubOrganization
  url: https://github.com/containernetworking
- type: GitHubRepository
  url: https://github.com/containernetworking/cni
- type: GitHubRepository
  url: https://github.com/containernetworking/plugins
- type: JSONLDContext
  url: json-ld/cni-context.jsonld
- type: JSONSchema
  url: json-schema/cni-network-config-schema.json
- type: JSONSchema
  url: json-schema/cni-result-schema.json
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com