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A generic CNI library to provide APIs for CNI plugin interactions. The library provides APIs to:

  • Load CNI network config from different sources
  • Setup networks for container namespace
  • Remove networks from container namespace
  • Query status of CNI network plugin initialization
  • Check verifies the network is still in desired state

go-cni aims to support plugins that implement Container Network Interface


package main

import (

	gocni "github.com/containerd/go-cni"

func main() {
	id := "example"
	netns := "/var/run/netns/example-ns-1"

	// CNI allows multiple CNI configurations and the network interface
	// will be named by eth0, eth1, ..., ethN.
	ifPrefixName := "eth"
	defaultIfName := "eth0"

	// Initializes library
	l, err := gocni.New(
		// one for loopback network interface
		// Sets the prefix for network interfaces, eth by default
	if err != nil {
		log.Fatalf("failed to initialize cni library: %v", err)

	// Load the cni configuration
	if err := l.Load(gocni.WithLoNetwork, gocni.WithDefaultConf); err != nil {
		log.Fatalf("failed to load cni configuration: %v", err)

	// Setup network for namespace.
	labels := map[string]string{
		"K8S_POD_NAMESPACE":          "namespace1",
		"K8S_POD_NAME":               "pod1",
		// Plugin tolerates all Args embedded by unknown labels, like
		"IgnoreUnknown": "1",

	ctx := context.Background()

	// Teardown network
	defer func() {
		if err := l.Remove(ctx, id, netns, gocni.WithLabels(labels)); err != nil {
			log.Fatalf("failed to teardown network: %v", err)

	// Setup network
	result, err := l.Setup(ctx, id, netns, gocni.WithLabels(labels))
	if err != nil {
		log.Fatalf("failed to setup network for namespace: %v", err)

	// Get IP of the default interface
	IP := result.Interfaces[defaultIfName].IPConfigs[0].IP.String()
	fmt.Printf("IP of the default interface %s:%s", defaultIfName, IP)

Project details

The go-cni is a containerd sub-project, licensed under the Apache 2.0 license. As a containerd sub-project, you will find the:

information in our containerd/project repository.


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