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// Copyright 2014 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.
// Package skel provides skeleton code for a CNI plugin.
// In particular, it implements argument parsing and validation.
package skel
import (
"fmt"
"io/ioutil"
"log"
"os"
"github.com/containernetworking/cni/pkg/types"
)
// CmdArgs captures all the arguments passed in to the plugin
// via both env vars and stdin
type CmdArgs struct {
ContainerID string
Netns string
IfName string
Args string
Path string
StdinData []byte
}
type reqForCmdEntry map[string]bool
// PluginMain is the "main" for a plugin. It accepts
// two callback functions for add and del commands.
func PluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error) {
var cmd, contID, netns, ifName, args, path string
vars := []struct {
name string
val *string
reqForCmd reqForCmdEntry
}{
{
"CNI_COMMAND",
&cmd,
reqForCmdEntry{
"ADD": true,
"DEL": true,
},
},
{
"CNI_CONTAINERID",
&contID,
reqForCmdEntry{
"ADD": false,
"DEL": false,
},
},
{
"CNI_NETNS",
&netns,
reqForCmdEntry{
"ADD": true,
"DEL": false,
},
},
{
"CNI_IFNAME",
&ifName,
reqForCmdEntry{
"ADD": true,
"DEL": true,
},
},
{
"CNI_ARGS",
&args,
reqForCmdEntry{
"ADD": false,
"DEL": false,
},
},
{
"CNI_PATH",
&path,
reqForCmdEntry{
"ADD": true,
"DEL": true,
},
},
}
argsMissing := false
for _, v := range vars {
*v.val = os.Getenv(v.name)
if v.reqForCmd[cmd] && *v.val == "" {
log.Printf("%v env variable missing", v.name)
argsMissing = true
}
}
if argsMissing {
dieMsg("required env variables missing")
}
stdinData, err := ioutil.ReadAll(os.Stdin)
if err != nil {
dieMsg("error reading from stdin: %v", err)
}
cmdArgs := &CmdArgs{
ContainerID: contID,
Netns: netns,
IfName: ifName,
Args: args,
Path: path,
StdinData: stdinData,
}
switch cmd {
case "ADD":
err = cmdAdd(cmdArgs)
case "DEL":
err = cmdDel(cmdArgs)
default:
dieMsg("unknown CNI_COMMAND: %v", cmd)
}
if err != nil {
if e, ok := err.(*types.Error); ok {
// don't wrap Error in Error
dieErr(e)
}
dieMsg(err.Error())
}
}
func dieMsg(f string, args ...interface{}) {
e := &types.Error{
Code: 100,
Msg: fmt.Sprintf(f, args...),
}
dieErr(e)
}
func dieErr(e *types.Error) {
if err := e.Print(); err != nil {
log.Print("Error writing error JSON to stdout: ", err)
}
os.Exit(1)
}
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