package daemon import ( "fmt" "io" "io/ioutil" "strings" "sync" "time" "github.com/Sirupsen/logrus" "github.com/docker/docker/daemon/execdriver" "github.com/docker/docker/pkg/broadcastwriter" "github.com/docker/docker/pkg/ioutils" "github.com/docker/docker/pkg/pools" "github.com/docker/docker/pkg/stringid" "github.com/docker/docker/runconfig" ) type execConfig struct { sync.Mutex ID string Running bool ExitCode int ProcessConfig *execdriver.ProcessConfig StreamConfig OpenStdin bool OpenStderr bool OpenStdout bool Container *Container canRemove bool // waitStart will be closed immediately after the exec is really started. waitStart chan struct{} } type execStore struct { s map[string]*execConfig sync.RWMutex } func newExecStore() *execStore { return &execStore{s: make(map[string]*execConfig, 0)} } func (e *execStore) Add(id string, execConfig *execConfig) { e.Lock() e.s[id] = execConfig e.Unlock() } func (e *execStore) Get(id string) *execConfig { e.RLock() res := e.s[id] e.RUnlock() return res } func (e *execStore) Delete(id string) { e.Lock() delete(e.s, id) e.Unlock() } func (e *execStore) List() []string { var IDs []string e.RLock() for id := range e.s { IDs = append(IDs, id) } e.RUnlock() return IDs } func (execConfig *execConfig) Resize(h, w int) error { select { case <-execConfig.waitStart: case <-time.After(time.Second): return fmt.Errorf("Exec %s is not running, so it can not be resized.", execConfig.ID) } return execConfig.ProcessConfig.Terminal.Resize(h, w) } func (d *Daemon) registerExecCommand(execConfig *execConfig) { // Storing execs in container in order to kill them gracefully whenever the container is stopped or removed. execConfig.Container.execCommands.Add(execConfig.ID, execConfig) // Storing execs in daemon for easy access via remote API. d.execCommands.Add(execConfig.ID, execConfig) } func (d *Daemon) getExecConfig(name string) (*execConfig, error) { execConfig := d.execCommands.Get(name) // If the exec is found but its container is not in the daemon's list of // containers then it must have been delete, in which case instead of // saying the container isn't running, we should return a 404 so that // the user sees the same error now that they will after the // 5 minute clean-up loop is run which erases old/dead execs. if execConfig != nil && d.containers.Get(execConfig.Container.ID) != nil { if !execConfig.Container.IsRunning() { return nil, fmt.Errorf("Container %s is not running", execConfig.Container.ID) } return execConfig, nil } return nil, fmt.Errorf("No such exec instance '%s' found in daemon", name) } func (d *Daemon) unregisterExecCommand(execConfig *execConfig) { execConfig.Container.execCommands.Delete(execConfig.ID) d.execCommands.Delete(execConfig.ID) } func (d *Daemon) getActiveContainer(name string) (*Container, error) { container, err := d.Get(name) if err != nil { return nil, err } if !container.IsRunning() { return nil, fmt.Errorf("Container %s is not running", name) } if container.IsPaused() { return nil, fmt.Errorf("Container %s is paused, unpause the container before exec", name) } return container, nil } func (d *Daemon) ContainerExecCreate(config *runconfig.ExecConfig) (string, error) { // Not all drivers support Exec (LXC for example) if err := checkExecSupport(d.execDriver.Name()); err != nil { return "", err } container, err := d.getActiveContainer(config.Container) if err != nil { return "", err } cmd := runconfig.NewCommand(config.Cmd...) entrypoint, args := d.getEntrypointAndArgs(runconfig.NewEntrypoint(), cmd) user := config.User if len(user) == 0 { user = container.Config.User } processConfig := &execdriver.ProcessConfig{ Tty: config.Tty, Entrypoint: entrypoint, Arguments: args, User: user, } execConfig := &execConfig{ ID: stringid.GenerateNonCryptoID(), OpenStdin: config.AttachStdin, OpenStdout: config.AttachStdout, OpenStderr: config.AttachStderr, StreamConfig: StreamConfig{}, ProcessConfig: processConfig, Container: container, Running: false, waitStart: make(chan struct{}), } d.registerExecCommand(execConfig) container.LogEvent("exec_create: " + execConfig.ProcessConfig.Entrypoint + " " + strings.Join(execConfig.ProcessConfig.Arguments, " ")) return execConfig.ID, nil } func (d *Daemon) ContainerExecStart(execName string, stdin io.ReadCloser, stdout io.Writer, stderr io.Writer) error { var ( cStdin io.ReadCloser cStdout, cStderr io.Writer ) execConfig, err := d.getExecConfig(execName) if err != nil { return err } func() { execConfig.Lock() defer execConfig.Unlock() if execConfig.Running { err = fmt.Errorf("Error: Exec command %s is already running", execName) } execConfig.Running = true }() if err != nil { return err } logrus.Debugf("starting exec command %s in container %s", execConfig.ID, execConfig.Container.ID) container := execConfig.Container container.LogEvent("exec_start: " + execConfig.ProcessConfig.Entrypoint + " " + strings.Join(execConfig.ProcessConfig.Arguments, " ")) if execConfig.OpenStdin { r, w := io.Pipe() go func() { defer w.Close() defer logrus.Debugf("Closing buffered stdin pipe") pools.Copy(w, stdin) }() cStdin = r } if execConfig.OpenStdout { cStdout = stdout } if execConfig.OpenStderr { cStderr = stderr } execConfig.StreamConfig.stderr = broadcastwriter.New() execConfig.StreamConfig.stdout = broadcastwriter.New() // Attach to stdin if execConfig.OpenStdin { execConfig.StreamConfig.stdin, execConfig.StreamConfig.stdinPipe = io.Pipe() } else { execConfig.StreamConfig.stdinPipe = ioutils.NopWriteCloser(ioutil.Discard) // Silently drop stdin } attachErr := attach(&execConfig.StreamConfig, execConfig.OpenStdin, true, execConfig.ProcessConfig.Tty, cStdin, cStdout, cStderr) execErr := make(chan error) // Note, the execConfig data will be removed when the container // itself is deleted. This allows us to query it (for things like // the exitStatus) even after the cmd is done running. go func() { if err := container.Exec(execConfig); err != nil { execErr <- fmt.Errorf("Cannot run exec command %s in container %s: %s", execName, container.ID, err) } }() select { case err := <-attachErr: if err != nil { return fmt.Errorf("attach failed with error: %s", err) } break case err := <-execErr: return err } return nil } func (d *Daemon) Exec(c *Container, execConfig *execConfig, pipes *execdriver.Pipes, startCallback execdriver.StartCallback) (int, error) { exitStatus, err := d.execDriver.Exec(c.command, execConfig.ProcessConfig, pipes, startCallback) // On err, make sure we don't leave ExitCode at zero if err != nil && exitStatus == 0 { exitStatus = 128 } execConfig.ExitCode = exitStatus execConfig.Running = false return exitStatus, err } // execCommandGC runs a ticker to clean up the daemon references // of exec configs that are no longer part of the container. func (d *Daemon) execCommandGC() { for range time.Tick(5 * time.Minute) { var ( cleaned int liveExecCommands = d.containerExecIds() ) for id, config := range d.execCommands.s { if config.canRemove { cleaned++ d.execCommands.Delete(id) } else { if _, exists := liveExecCommands[id]; !exists { config.canRemove = true } } } if cleaned > 0 { logrus.Debugf("clean %d unused exec commands", cleaned) } } } // containerExecIds returns a list of all the current exec ids that are in use // and running inside a container. func (d *Daemon) containerExecIds() map[string]struct{} { ids := map[string]struct{}{} for _, c := range d.containers.List() { for _, id := range c.execCommands.List() { ids[id] = struct{}{} } } return ids }