plugins/sample/main.go

// Copyright 2017 CNI authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// This is a sample chained plugin that supports multiple CNI versions. It
// parses prevResult according to the cniVersion
package main

import (
	"encoding/json"
	"fmt"
	"net"

	"github.com/containernetworking/cni/pkg/skel"
	"github.com/containernetworking/cni/pkg/types"
	"github.com/containernetworking/cni/pkg/types/current"
	"github.com/containernetworking/cni/pkg/version"
)

// PluginConf is whatever you expect your configuration json to be. This is whatever
// is passed in on stdin. Your plugin may wish to expose its functionality via
// runtime args, see CONVENTIONS.md in the CNI spec.
type PluginConf struct {
	types.NetConf // You may wish to not nest this type
	RuntimeConfig *struct {
		SampleConfig map[string]interface{} `json:"sample"`
	} `json:"runtimeConfig"`

	// This is the previous result, when called in the context of a chained
	// plugin. Because this plugin supports multiple versions, we'll have to
	// parse this in two passes. If your plugin is not chained, this can be
	// removed (though you may wish to error if a non-chainable plugin is
	// chained.
	// If you need to modify the result before returning it, you will need
	// to actually convert it to a concrete versioned struct.
	RawPrevResult *map[string]interface{} `json:"prevResult"`
	PrevResult    *current.Result         `json:"-"`

	// Add plugin-specifc flags here
	MyAwesomeFlag     bool   `json:"myAwesomeFlag"`
	AnotherAwesomeArg string `json:"anotherAwesomeArg"`
}

// parseConfig parses the supplied configuration (and prevResult) from stdin.
func parseConfig(stdin []byte) (*PluginConf, error) {
	conf := PluginConf{}

	if err := json.Unmarshal(stdin, &conf); err != nil {
		return nil, fmt.Errorf("failed to parse network configuration: %v", err)
	}

	// Parse previous result. Remove this if your plugin is not chained.
	if conf.RawPrevResult != nil {
		resultBytes, err := json.Marshal(conf.RawPrevResult)
		if err != nil {
			return nil, fmt.Errorf("could not serialize prevResult: %v", err)
		}
		res, err := version.NewResult(conf.CNIVersion, resultBytes)
		if err != nil {
			return nil, fmt.Errorf("could not parse prevResult: %v", err)
		}
		conf.RawPrevResult = nil
		conf.PrevResult, err = current.NewResultFromResult(res)
		if err != nil {
			return nil, fmt.Errorf("could not convert result to current version: %v", err)
		}
	}
	// End previous result parsing

	// Do any validation here
	if conf.AnotherAwesomeArg == "" {
		return nil, fmt.Errorf("anotherAwesomeArg must be specified")
	}

	return &conf, nil
}

// cmdAdd is called for ADD requests
func cmdAdd(args *skel.CmdArgs) error {
	conf, err := parseConfig(args.StdinData)
	if err != nil {
		return err
	}

	if conf.PrevResult == nil {
		return fmt.Errorf("must be called as chained plugin")
	}

	// This is some sample code to generate the list of container-side IPs.
	// We're casting the prevResult to a 0.3.0 response, which can also include
	// host-side IPs (but doesn't when converted from a 0.2.0 response).
	containerIPs := make([]net.IP, 0, len(conf.PrevResult.IPs))
	if conf.CNIVersion != "0.3.0" {
		for _, ip := range conf.PrevResult.IPs {
			containerIPs = append(containerIPs, ip.Address.IP)
		}
	} else {
		for _, ip := range conf.PrevResult.IPs {
			if ip.Interface == nil {
				continue
			}
			intIdx := *ip.Interface
			// Every IP is indexed in to the interfaces array, with "-1" standing
			// for an unknown interface (which we'll assume to be Container-side
			// Skip all IPs we know belong to an interface with the wrong name.
			if intIdx >= 0 && intIdx < len(conf.PrevResult.Interfaces) && conf.PrevResult.Interfaces[intIdx].Name != args.IfName {
				continue
			}
			containerIPs = append(containerIPs, ip.Address.IP)
		}
	}
	if len(containerIPs) == 0 {
		return fmt.Errorf("got no container IPs")
	}

	// Pass through the result for the next plugin
	return types.PrintResult(conf.PrevResult, conf.CNIVersion)
}

// cmdDel is called for DELETE requests
func cmdDel(args *skel.CmdArgs) error {
	conf, err := parseConfig(args.StdinData)
	if err != nil {
		return err
	}
	_ = conf

	// Do your delete here

	return nil
}

func main() {
	skel.PluginMain(cmdAdd, cmdDel, version.PluginSupports("", "0.1.0", "0.2.0", version.Current()))
}