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shim.go
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shim.go
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/*
Copyright The containerd 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 shim
import (
"context"
"flag"
"fmt"
"io"
"os"
"runtime"
"runtime/debug"
"strings"
"time"
"github.com/containerd/containerd/events"
"github.com/containerd/containerd/log"
"github.com/containerd/containerd/namespaces"
shimapi "github.com/containerd/containerd/runtime/v2/task"
"github.com/containerd/containerd/version"
"github.com/containerd/ttrpc"
"github.com/gogo/protobuf/proto"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
// Client for a shim server
type Client struct {
service shimapi.TaskService
context context.Context
signals chan os.Signal
}
// Publisher for events
type Publisher interface {
events.Publisher
io.Closer
}
// Init func for the creation of a shim server
type Init func(context.Context, string, Publisher, func()) (Shim, error)
// Shim server interface
type Shim interface {
shimapi.TaskService
Cleanup(ctx context.Context) (*shimapi.DeleteResponse, error)
StartShim(ctx context.Context, id, containerdBinary, containerdAddress, containerdTTRPCAddress string) (string, error)
}
// OptsKey is the context key for the Opts value.
type OptsKey struct{}
// Opts are context options associated with the shim invocation.
type Opts struct {
BundlePath string
Debug bool
}
// BinaryOpts allows the configuration of a shims binary setup
type BinaryOpts func(*Config)
// Config of shim binary options provided by shim implementations
type Config struct {
// NoSubreaper disables setting the shim as a child subreaper
NoSubreaper bool
// NoReaper disables the shim binary from reaping any child process implicitly
NoReaper bool
// NoSetupLogger disables automatic configuration of logrus to use the shim FIFO
NoSetupLogger bool
}
var (
debugFlag bool
versionFlag bool
idFlag string
namespaceFlag string
socketFlag string
bundlePath string
addressFlag string
containerdBinaryFlag string
action string
)
const (
ttrpcAddressEnv = "TTRPC_ADDRESS"
)
func parseFlags() {
flag.BoolVar(&debugFlag, "debug", false, "enable debug output in logs")
flag.BoolVar(&versionFlag, "v", false, "show the shim version and exit")
flag.StringVar(&namespaceFlag, "namespace", "", "namespace that owns the shim")
flag.StringVar(&idFlag, "id", "", "id of the task")
flag.StringVar(&socketFlag, "socket", "", "socket path to serve")
flag.StringVar(&bundlePath, "bundle", "", "path to the bundle if not workdir")
flag.StringVar(&addressFlag, "address", "", "grpc address back to main containerd")
flag.StringVar(&containerdBinaryFlag, "publish-binary", "containerd", "path to publish binary (used for publishing events)")
flag.Parse()
action = flag.Arg(0)
}
func setRuntime() {
debug.SetGCPercent(40)
go func() {
for range time.Tick(30 * time.Second) {
debug.FreeOSMemory()
}
}()
if os.Getenv("GOMAXPROCS") == "" {
// If GOMAXPROCS hasn't been set, we default to a value of 2 to reduce
// the number of Go stacks present in the shim.
runtime.GOMAXPROCS(2)
}
}
func setLogger(ctx context.Context, id string) error {
logrus.SetFormatter(&logrus.TextFormatter{
TimestampFormat: log.RFC3339NanoFixed,
FullTimestamp: true,
})
if debugFlag {
logrus.SetLevel(logrus.DebugLevel)
}
f, err := openLog(ctx, id)
if err != nil {
return err
}
logrus.SetOutput(f)
return nil
}
// Run initializes and runs a shim server
func Run(id string, initFunc Init, opts ...BinaryOpts) {
var config Config
for _, o := range opts {
o(&config)
}
if err := run(id, initFunc, config); err != nil {
fmt.Fprintf(os.Stderr, "%s: %s\n", id, err)
os.Exit(1)
}
}
func run(id string, initFunc Init, config Config) error {
parseFlags()
if versionFlag {
fmt.Printf("%s:\n", os.Args[0])
fmt.Println(" Version: ", version.Version)
fmt.Println(" Revision:", version.Revision)
fmt.Println(" Go version:", version.GoVersion)
fmt.Println("")
return nil
}
setRuntime()
signals, err := setupSignals(config)
if err != nil {
return err
}
if !config.NoSubreaper {
if err := subreaper(); err != nil {
return err
}
}
ttrpcAddress := os.Getenv(ttrpcAddressEnv)
publisher, err := NewPublisher(ttrpcAddress)
if err != nil {
return err
}
defer publisher.Close()
if namespaceFlag == "" {
return fmt.Errorf("shim namespace cannot be empty")
}
ctx := namespaces.WithNamespace(context.Background(), namespaceFlag)
ctx = context.WithValue(ctx, OptsKey{}, Opts{BundlePath: bundlePath, Debug: debugFlag})
ctx = log.WithLogger(ctx, log.G(ctx).WithField("runtime", id))
ctx, cancel := context.WithCancel(ctx)
service, err := initFunc(ctx, idFlag, publisher, cancel)
if err != nil {
return err
}
switch action {
case "delete":
logger := logrus.WithFields(logrus.Fields{
"pid": os.Getpid(),
"namespace": namespaceFlag,
})
go handleSignals(ctx, logger, signals)
response, err := service.Cleanup(ctx)
if err != nil {
return err
}
data, err := proto.Marshal(response)
if err != nil {
return err
}
if _, err := os.Stdout.Write(data); err != nil {
return err
}
return nil
case "start":
address, err := service.StartShim(ctx, idFlag, containerdBinaryFlag, addressFlag, ttrpcAddress)
if err != nil {
return err
}
if _, err := os.Stdout.WriteString(address); err != nil {
return err
}
return nil
default:
if !config.NoSetupLogger {
if err := setLogger(ctx, idFlag); err != nil {
return err
}
}
client := NewShimClient(ctx, service, signals)
if err := client.Serve(); err != nil {
if err != context.Canceled {
return err
}
}
select {
case <-publisher.Done():
return nil
case <-time.After(5 * time.Second):
return errors.New("publisher not closed")
}
}
}
// NewShimClient creates a new shim server client
func NewShimClient(ctx context.Context, svc shimapi.TaskService, signals chan os.Signal) *Client {
s := &Client{
service: svc,
context: ctx,
signals: signals,
}
return s
}
// Serve the shim server
func (s *Client) Serve() error {
dump := make(chan os.Signal, 32)
setupDumpStacks(dump)
path, err := os.Getwd()
if err != nil {
return err
}
server, err := newServer()
if err != nil {
return errors.Wrap(err, "failed creating server")
}
logrus.Debug("registering ttrpc server")
shimapi.RegisterTaskService(server, s.service)
if err := serve(s.context, server, socketFlag); err != nil {
return err
}
logger := logrus.WithFields(logrus.Fields{
"pid": os.Getpid(),
"path": path,
"namespace": namespaceFlag,
})
go func() {
for range dump {
dumpStacks(logger)
}
}()
return handleSignals(s.context, logger, s.signals)
}
// serve serves the ttrpc API over a unix socket at the provided path
// this function does not block
func serve(ctx context.Context, server *ttrpc.Server, path string) error {
l, err := serveListener(path)
if err != nil {
return err
}
go func() {
if err := server.Serve(ctx, l); err != nil &&
!strings.Contains(err.Error(), "use of closed network connection") {
logrus.WithError(err).Fatal("containerd-shim: ttrpc server failure")
}
l.Close()
if address, err := ReadAddress("address"); err == nil {
_ = RemoveSocket(address)
}
}()
return nil
}
func dumpStacks(logger *logrus.Entry) {
var (
buf []byte
stackSize int
)
bufferLen := 16384
for stackSize == len(buf) {
buf = make([]byte, bufferLen)
stackSize = runtime.Stack(buf, true)
bufferLen *= 2
}
buf = buf[:stackSize]
logger.Infof("=== BEGIN goroutine stack dump ===\n%s\n=== END goroutine stack dump ===", buf)
}