godeps: initial creation

vendor/github.com/containernetworking/cni/pkg/skel/skel.go

@@ -0,0 +1,228 @@
+// Copyright 2014-2016 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"
+	"io/ioutil"
+	"log"
+	"os"
+
+	"github.com/containernetworking/cni/pkg/types"
+	"github.com/containernetworking/cni/pkg/version"
+)
+
+// 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 dispatcher struct {
+	Getenv func(string) string
+	Stdin  io.Reader
+	Stdout io.Writer
+	Stderr io.Writer
+
+	ConfVersionDecoder version.ConfigDecoder
+	VersionReconciler  version.Reconciler
+}
+
+type reqForCmdEntry map[string]bool
+
+func (t *dispatcher) getCmdArgsFromEnv() (string, *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 = t.Getenv(v.name)
+		if *v.val == "" {
+			if v.reqForCmd[cmd] || v.name == "CNI_COMMAND" {
+				fmt.Fprintf(t.Stderr, "%v env variable missing\n", v.name)
+				argsMissing = true
+			}
+		}
+	}
+
+	if argsMissing {
+		return "", nil, fmt.Errorf("required env variables missing")
+	}
+
+	stdinData, err := ioutil.ReadAll(t.Stdin)
+	if err != nil {
+		return "", nil, fmt.Errorf("error reading from stdin: %v", err)
+	}
+
+	cmdArgs := &CmdArgs{
+		ContainerID: contID,
+		Netns:       netns,
+		IfName:      ifName,
+		Args:        args,
+		Path:        path,
+		StdinData:   stdinData,
+	}
+	return cmd, cmdArgs, nil
+}
+
+func createTypedError(f string, args ...interface{}) *types.Error {
+	return &types.Error{
+		Code: 100,
+		Msg:  fmt.Sprintf(f, args...),
+	}
+}
+
+func (t *dispatcher) checkVersionAndCall(cmdArgs *CmdArgs, pluginVersionInfo version.PluginInfo, toCall func(*CmdArgs) error) error {
+	configVersion, err := t.ConfVersionDecoder.Decode(cmdArgs.StdinData)
+	if err != nil {
+		return err
+	}
+	verErr := t.VersionReconciler.Check(configVersion, pluginVersionInfo)
+	if verErr != nil {
+		return &types.Error{
+			Code:    types.ErrIncompatibleCNIVersion,
+			Msg:     "incompatible CNI versions",
+			Details: verErr.Details(),
+		}
+	}
+	return toCall(cmdArgs)
+}
+
+func (t *dispatcher) pluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error, versionInfo version.PluginInfo) *types.Error {
+	cmd, cmdArgs, err := t.getCmdArgsFromEnv()
+	if err != nil {
+		return createTypedError(err.Error())
+	}
+
+	switch cmd {
+	case "ADD":
+		err = t.checkVersionAndCall(cmdArgs, versionInfo, cmdAdd)
+	case "DEL":
+		err = t.checkVersionAndCall(cmdArgs, versionInfo, cmdDel)
+	case "VERSION":
+		err = versionInfo.Encode(t.Stdout)
+	default:
+		return createTypedError("unknown CNI_COMMAND: %v", cmd)
+	}
+
+	if err != nil {
+		if e, ok := err.(*types.Error); ok {
+			// don't wrap Error in Error
+			return e
+		}
+		return createTypedError(err.Error())
+	}
+	return nil
+}
+
+// PluginMainWithError is the core "main" for a plugin. It accepts
+// callback functions for add and del CNI commands and returns an error.
+//
+// The caller must also specify what CNI spec versions the plugin supports.
+//
+// It is the responsibility of the caller to check for non-nil error return.
+//
+// For a plugin to comply with the CNI spec, it must print any error to stdout
+// as JSON and then exit with nonzero status code.
+//
+// To let this package automatically handle errors and call os.Exit(1) for you,
+// use PluginMain() instead.
+func PluginMainWithError(cmdAdd, cmdDel func(_ *CmdArgs) error, versionInfo version.PluginInfo) *types.Error {
+	return (&dispatcher{
+		Getenv: os.Getenv,
+		Stdin:  os.Stdin,
+		Stdout: os.Stdout,
+		Stderr: os.Stderr,
+	}).pluginMain(cmdAdd, cmdDel, versionInfo)
+}
+
+// PluginMain is the core "main" for a plugin which includes automatic error handling.
+//
+// The caller must also specify what CNI spec versions the plugin supports.
+//
+// When an error occurs in either cmdAdd or cmdDel, PluginMain will print the error
+// as JSON to stdout and call os.Exit(1).
+//
+// To have more control over error handling, use PluginMainWithError() instead.
+func PluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error, versionInfo version.PluginInfo) {
+	if e := PluginMainWithError(cmdAdd, cmdDel, versionInfo); e != nil {
+		if err := e.Print(); err != nil {
+			log.Print("Error writing error JSON to stdout: ", err)
+		}
+		os.Exit(1)
+	}
+}