Add grpc service to shim
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
This commit is contained in:
Michael Crosby
parent
e6de7ea4b5
commit
c08e0e610c
8 changed files with 402 additions and 229 deletions
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@ -1,210 +1,104 @@
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package main
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import (
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"flag"
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"fmt"
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"os"
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"os/signal"
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"path/filepath"
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"runtime"
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"syscall"
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"google.golang.org/grpc"
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"github.com/docker/containerd"
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"github.com/docker/containerd/api/shim"
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"github.com/docker/containerd/sys"
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"github.com/docker/docker/pkg/term"
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"github.com/docker/containerd/utils"
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"github.com/sirupsen/logrus"
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"github.com/urfave/cli"
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)
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func writeMessage(f *os.File, level string, err error) {
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fmt.Fprintf(f, `{"level": "%s","msg": "%s"}`, level, err)
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f.Sync()
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}
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const usage = `
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__ _ __ __ _
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_________ ____ / /_____ _(_)___ ___ _________/ / _____/ /_ (_)___ ___
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/ ___/ __ \/ __ \/ __/ __ ` + "`" + `/ / __ \/ _ \/ ___/ __ /_____/ ___/ __ \/ / __ ` + "`" + `__ \
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/ /__/ /_/ / / / / /_/ /_/ / / / / / __/ / / /_/ /_____(__ ) / / / / / / / / /
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\___/\____/_/ /_/\__/\__,_/_/_/ /_/\___/_/ \__,_/ /____/_/ /_/_/_/ /_/ /_/
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shim for container lifecycle and reconnection
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`
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type controlMessage struct {
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Type int
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Width int
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Height int
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}
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// containerd-shim is a small shim that sits in front of a runtime implementation
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// that allows it to be reparented to init and handle reattach from the caller.
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//
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// the cwd of the shim should be the path to the state directory where the shim
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// can locate fifos and other information.
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// Arg0: id of the container
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// Arg1: bundle path
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// Arg2: runtime binary
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func main() {
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flag.Parse()
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cwd, err := os.Getwd()
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if err != nil {
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panic(err)
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app := cli.NewApp()
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app.Name = "containerd-shim"
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app.Version = containerd.Version
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app.Usage = usage
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app.Flags = []cli.Flag{
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cli.BoolFlag{
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Name: "debug",
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Usage: "enable debug output in logs",
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},
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}
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f, err := os.OpenFile(filepath.Join(cwd, "shim-log.json"), os.O_CREATE|os.O_WRONLY|os.O_APPEND|os.O_SYNC, 0666)
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if err != nil {
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panic(err)
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}
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if err := start(f); err != nil {
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// this means that the runtime failed starting the container and will have the
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// proper error messages in the runtime log so we should to treat this as a
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// shim failure because the sim executed properly
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if err == errRuntime {
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f.Close()
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return
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app.Before = func(context *cli.Context) error {
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if context.GlobalBool("debug") {
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logrus.SetLevel(logrus.DebugLevel)
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}
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// log the error instead of writing to stderr because the shim will have
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// /dev/null as it's stdio because it is supposed to be reparented to system
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// init and will not have anyone to read from it
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writeMessage(f, "error", err)
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f.Close()
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return nil
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}
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app.Action = func(context *cli.Context) error {
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// start handling signals as soon as possible so that things are properly reaped
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// or if runtime exits before we hit the handler
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signals, err := setupSignals()
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if err != nil {
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return err
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}
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var (
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server = grpc.NewServer()
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sv = &service{}
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)
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shim.RegisterShimServiceServer(server, sv)
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l, err := utils.CreateUnixSocket("shim.sock")
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if err != nil {
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return err
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}
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go func() {
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defer l.Close()
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if err := server.Serve(l); err != nil {
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l.Close()
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logrus.WithError(err).Fatal("containerd-shim: GRPC server failure")
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}
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}()
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for s := range signals {
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switch s {
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case syscall.SIGCHLD:
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exits, err := utils.Reap(false)
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if err != nil {
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logrus.WithError(err).Error("reap exit status")
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}
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for _, e := range exits {
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if err := sv.processExited(e); err != nil {
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return err
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}
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}
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case syscall.SIGTERM, syscall.SIGINT:
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server.GracefulStop()
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return nil
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}
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}
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return nil
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}
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if err := app.Run(os.Args); err != nil {
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fmt.Fprintf(os.Stderr, "containerd-shim: %s\n", err)
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os.Exit(1)
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}
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}
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func start(log *os.File) error {
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// start handling signals as soon as possible so that things are properly reaped
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// or if runtime exits before we hit the handler
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// setupSignals creates a new signal handler for all signals and sets the shim as a
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// sub-reaper so that the container processes are reparented
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func setupSignals() (chan os.Signal, error) {
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signals := make(chan os.Signal, 2048)
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signal.Notify(signals)
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// set the shim as the subreaper for all orphaned processes created by the container
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if err := sys.SetSubreaper(1); err != nil {
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return err
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return nil, err
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}
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// open the exit pipe
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f, err := os.OpenFile("exit", syscall.O_WRONLY, 0)
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if err != nil {
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return err
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}
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defer f.Close()
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control, err := os.OpenFile("control", syscall.O_RDWR, 0)
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if err != nil {
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return err
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}
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defer control.Close()
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p, err := newProcess(flag.Arg(0), flag.Arg(1), flag.Arg(2))
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if err != nil {
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return err
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}
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defer func() {
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if err := p.Close(); err != nil {
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writeMessage(log, "warn", err)
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}
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}()
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if err := p.create(); err != nil {
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p.delete()
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return err
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}
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msgC := make(chan controlMessage, 32)
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go func() {
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for {
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var m controlMessage
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if _, err := fmt.Fscanf(control, "%d %d %d\n", &m.Type, &m.Width, &m.Height); err != nil {
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continue
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}
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msgC <- m
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}
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}()
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if runtime.GOOS == "solaris" {
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return nil
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}
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var exitShim bool
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for !exitShim {
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select {
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case s := <-signals:
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switch s {
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case syscall.SIGCHLD:
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exits, _ := Reap(false)
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for _, e := range exits {
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// check to see if runtime is one of the processes that has exited
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if e.Pid == p.pid() {
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exitShim = true
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writeInt("exitStatus", e.Status)
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}
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}
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}
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case msg := <-msgC:
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switch msg.Type {
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case 0:
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// close stdin
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if p.stdinCloser != nil {
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p.stdinCloser.Close()
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}
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case 1:
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if p.console == nil {
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continue
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}
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ws := term.Winsize{
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Width: uint16(msg.Width),
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Height: uint16(msg.Height),
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}
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term.SetWinsize(p.console.Fd(), &ws)
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}
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}
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}
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// runtime has exited so the shim can also exit
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// kill all processes in the container incase it was not running in
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// its own PID namespace
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p.killAll()
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// wait for all the processes and IO to finish
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p.Wait()
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// delete the container from the runtime
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p.delete()
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// the close of the exit fifo will happen when the shim exits
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return nil
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}
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func writeInt(path string, i int) error {
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f, err := os.Create(path)
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if err != nil {
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return err
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}
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defer f.Close()
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_, err = fmt.Fprintf(f, "%d", i)
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return err
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}
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// Exit is the wait4 information from an exited process
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type Exit struct {
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Pid int
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Status int
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}
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// Reap reaps all child processes for the calling process and returns their
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// exit information
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func Reap(wait bool) (exits []Exit, err error) {
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var (
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ws syscall.WaitStatus
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rus syscall.Rusage
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)
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flag := syscall.WNOHANG
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if wait {
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flag = 0
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}
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for {
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pid, err := syscall.Wait4(-1, &ws, flag, &rus)
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if err != nil {
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if err == syscall.ECHILD {
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return exits, nil
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}
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return exits, err
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}
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if pid <= 0 {
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return exits, nil
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}
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exits = append(exits, Exit{
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Pid: pid,
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Status: exitStatus(ws),
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})
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}
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}
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const exitSignalOffset = 128
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// exitStatus returns the correct exit status for a process based on if it
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// was signaled or exited cleanly
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func exitStatus(status syscall.WaitStatus) int {
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if status.Signaled() {
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return exitSignalOffset + int(status.Signal())
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}
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return status.ExitStatus()
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return signals, nil
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}
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