b88f173c43
This takes some of the machinery from CNI and from the rkt networking code, and turns it into a library that can be linked into go apps. Included is an example command-line application that uses the library, called `cnitool`. Other headline changes: * Plugin exec'ing is factored out The motivation here is to factor out the protocol for invoking plugins. To that end, a generalisation of the code from api.go and pkg/plugin/ipam.go goes into pkg/invoke/exec.go. * Move argument-handling and conf-loading into public API The fact that the arguments get turned into an environment for the plugin is incidental to the API; so, provide a way of supplying them as a struct or saying "just use the same arguments as I got" (the latter is for IPAM plugins).
118 lines
2.5 KiB
Go
118 lines
2.5 KiB
Go
// Copyright 2014 CoreOS, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package skel provides skeleton code for a CNI plugin.
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// In particular, it implements argument parsing and validation.
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package skel
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import (
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"fmt"
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"io/ioutil"
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"log"
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"os"
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"github.com/appc/cni/pkg/types"
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)
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// CmdArgs captures all the arguments passed in to the plugin
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// via both env vars and stdin
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type CmdArgs struct {
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ContainerID string
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Netns string
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IfName string
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Args string
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Path string
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StdinData []byte
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}
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// PluginMain is the "main" for a plugin. It accepts
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// two callback functions for add and del commands.
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func PluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error) {
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var cmd, contID, netns, ifName, args, path string
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vars := []struct {
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name string
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val *string
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req bool
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}{
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{"CNI_COMMAND", &cmd, true},
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{"CNI_CONTAINERID", &contID, false},
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{"CNI_NETNS", &netns, true},
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{"CNI_IFNAME", &ifName, true},
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{"CNI_ARGS", &args, false},
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{"CNI_PATH", &path, true},
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}
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argsMissing := false
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for _, v := range vars {
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*v.val = os.Getenv(v.name)
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if v.req && *v.val == "" {
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log.Printf("%v env variable missing", v.name)
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argsMissing = true
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}
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}
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if argsMissing {
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dieMsg("required env variables missing")
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}
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stdinData, err := ioutil.ReadAll(os.Stdin)
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if err != nil {
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dieMsg("error reading from stdin: %v", err)
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}
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cmdArgs := &CmdArgs{
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ContainerID: contID,
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Netns: netns,
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IfName: ifName,
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Args: args,
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Path: path,
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StdinData: stdinData,
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}
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switch cmd {
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case "ADD":
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err = cmdAdd(cmdArgs)
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case "DEL":
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err = cmdDel(cmdArgs)
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default:
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dieMsg("unknown CNI_COMMAND: %v", cmd)
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}
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if err != nil {
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if e, ok := err.(*types.Error); ok {
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// don't wrap Error in Error
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dieErr(e)
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}
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dieMsg(err.Error())
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}
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}
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func dieMsg(f string, args ...interface{}) {
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e := &types.Error{
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Code: 100,
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Msg: fmt.Sprintf(f, args...),
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}
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dieErr(e)
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}
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func dieErr(e *types.Error) {
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if err := e.Print(); err != nil {
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log.Print("Error writing error JSON to stdout: ", err)
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}
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os.Exit(1)
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}
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