package docker import ( "bytes" "encoding/json" "errors" "fmt" "github.com/dotcloud/docker/auth" "github.com/dotcloud/docker/rcli" "io" "log" "math/rand" "net/http" "net/url" "runtime" "strconv" "strings" "sync" "text/tabwriter" "time" ) const VERSION = "0.1.0" func (srv *Server) Name() string { return "docker" } // FIXME: Stop violating DRY by repeating usage here and in Subcmd declarations func (srv *Server) Help() string { help := "Usage: docker COMMAND [arg...]\n\nA self-sufficient runtime for linux containers.\n\nCommands:\n" for _, cmd := range [][]interface{}{ {"attach", "Attach to a running container"}, {"commit", "Create a new image from a container's changes"}, {"diff", "Inspect changes on a container's filesystem"}, {"export", "Stream the contents of a container as a tar archive"}, {"history", "Show the history of an image"}, {"images", "List images"}, {"import", "Create a new filesystem image from the contents of a tarball"}, {"info", "Display system-wide information"}, {"inspect", "Return low-level information on a container"}, {"kill", "Kill a running container"}, {"login", "Register or Login to the docker registry server"}, {"logs", "Fetch the logs of a container"}, {"port", "Lookup the public-facing port which is NAT-ed to PRIVATE_PORT"}, {"ps", "List containers"}, {"pull", "Pull an image or a repository to the docker registry server"}, {"push", "Push an image or a repository to the docker registry server"}, {"restart", "Restart a running container"}, {"rm", "Remove a container"}, {"rmi", "Remove an image"}, {"run", "Run a command in a new container"}, {"start", "Start a stopped container"}, {"stop", "Stop a running container"}, {"tag", "Tag an image into a repository"}, {"version", "Show the docker version information"}, {"wait", "Block until a container stops, then print its exit code"}, } { help += fmt.Sprintf(" %-10.10s%s\n", cmd[0], cmd[1]) } return help } // 'docker login': login / register a user to registry service. func (srv *Server) CmdLogin(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "login", "", "Register or Login to the docker registry server") if err := cmd.Parse(args); err != nil { return nil } var username string var password string var email string fmt.Fprint(stdout, "Username (", srv.runtime.authConfig.Username, "): ") fmt.Fscanf(stdin, "%s", &username) if username == "" { username = srv.runtime.authConfig.Username } if username != srv.runtime.authConfig.Username { fmt.Fprint(stdout, "Password: ") fmt.Fscanf(stdin, "%s", &password) if password == "" { return errors.New("Error : Password Required\n") } fmt.Fprint(stdout, "Email (", srv.runtime.authConfig.Email, "): ") fmt.Fscanf(stdin, "%s", &email) if email == "" { email = srv.runtime.authConfig.Email } } else { password = srv.runtime.authConfig.Password email = srv.runtime.authConfig.Email } newAuthConfig := auth.NewAuthConfig(username, password, email, srv.runtime.root) status, err := auth.Login(newAuthConfig) if err != nil { fmt.Fprintf(stdout, "Error : %s\n", err) } else { srv.runtime.authConfig = newAuthConfig } if status != "" { fmt.Fprintf(stdout, status) } return nil } // 'docker wait': block until a container stops func (srv *Server) CmdWait(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "wait", "[OPTIONS] NAME", "Block until a container stops, then print its exit code.") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() < 1 { cmd.Usage() return nil } for _, name := range cmd.Args() { if container := srv.runtime.Get(name); container != nil { fmt.Fprintln(stdout, container.Wait()) } else { return errors.New("No such container: " + name) } } return nil } // 'docker version': show version information func (srv *Server) CmdVersion(stdin io.ReadCloser, stdout io.Writer, args ...string) error { fmt.Fprintf(stdout, "Version:%s\n", VERSION) return nil } // 'docker info': display system-wide information. func (srv *Server) CmdInfo(stdin io.ReadCloser, stdout io.Writer, args ...string) error { images, _ := srv.runtime.graph.All() var imgcount int if images == nil { imgcount = 0 } else { imgcount = len(images) } cmd := rcli.Subcmd(stdout, "info", "", "Display system-wide information.") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() > 0 { cmd.Usage() return nil } fmt.Fprintf(stdout, "containers: %d\nversion: %s\nimages: %d\n", len(srv.runtime.List()), VERSION, imgcount) return nil } func (srv *Server) CmdStop(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "stop", "[OPTIONS] NAME", "Stop a running container") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() < 1 { cmd.Usage() return nil } for _, name := range cmd.Args() { if container := srv.runtime.Get(name); container != nil { if err := container.Stop(); err != nil { return err } fmt.Fprintln(stdout, container.Id) } else { return errors.New("No such container: " + name) } } return nil } func (srv *Server) CmdRestart(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "restart", "[OPTIONS] NAME", "Restart a running container") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() < 1 { cmd.Usage() return nil } for _, name := range cmd.Args() { if container := srv.runtime.Get(name); container != nil { if err := container.Restart(); err != nil { return err } fmt.Fprintln(stdout, container.Id) } else { return errors.New("No such container: " + name) } } return nil } func (srv *Server) CmdStart(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "start", "[OPTIONS] NAME", "Start a stopped container") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() < 1 { cmd.Usage() return nil } for _, name := range cmd.Args() { if container := srv.runtime.Get(name); container != nil { if err := container.Start(); err != nil { return err } fmt.Fprintln(stdout, container.Id) } else { return errors.New("No such container: " + name) } } return nil } func (srv *Server) CmdInspect(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "inspect", "[OPTIONS] CONTAINER", "Return low-level information on a container") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() < 1 { cmd.Usage() return nil } name := cmd.Arg(0) var obj interface{} if container := srv.runtime.Get(name); container != nil { obj = container } else if image, err := srv.runtime.repositories.LookupImage(name); err == nil && image != nil { obj = image } else { // No output means the object does not exist // (easier to script since stdout and stderr are not differentiated atm) return nil } data, err := json.Marshal(obj) if err != nil { return err } indented := new(bytes.Buffer) if err = json.Indent(indented, data, "", " "); err != nil { return err } if _, err := io.Copy(stdout, indented); err != nil { return err } stdout.Write([]byte{'\n'}) return nil } func (srv *Server) CmdPort(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "port", "[OPTIONS] CONTAINER PRIVATE_PORT", "Lookup the public-facing port which is NAT-ed to PRIVATE_PORT") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() != 2 { cmd.Usage() return nil } name := cmd.Arg(0) privatePort := cmd.Arg(1) if container := srv.runtime.Get(name); container == nil { return errors.New("No such container: " + name) } else { if frontend, exists := container.NetworkSettings.PortMapping[privatePort]; !exists { return fmt.Errorf("No private port '%s' allocated on %s", privatePort, name) } else { fmt.Fprintln(stdout, frontend) } } return nil } // 'docker rmi NAME' removes all images with the name NAME func (srv *Server) CmdRmi(stdin io.ReadCloser, stdout io.Writer, args ...string) (err error) { cmd := rcli.Subcmd(stdout, "rmimage", "[OPTIONS] IMAGE", "Remove an image") if cmd.Parse(args) != nil || cmd.NArg() < 1 { cmd.Usage() return nil } for _, name := range cmd.Args() { if err := srv.runtime.graph.Delete(name); err != nil { return err } } return nil } func (srv *Server) CmdHistory(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "history", "[OPTIONS] IMAGE", "Show the history of an image") if cmd.Parse(args) != nil || cmd.NArg() != 1 { cmd.Usage() return nil } image, err := srv.runtime.repositories.LookupImage(cmd.Arg(0)) if err != nil { return err } w := tabwriter.NewWriter(stdout, 20, 1, 3, ' ', 0) defer w.Flush() fmt.Fprintf(w, "ID\tCREATED\tCREATED BY\n") return image.WalkHistory(func(img *Image) error { fmt.Fprintf(w, "%s\t%s\t%s\n", srv.runtime.repositories.ImageName(img.Id), HumanDuration(time.Now().Sub(img.Created))+" ago", strings.Join(img.ContainerConfig.Cmd, " "), ) return nil }) } func (srv *Server) CmdRm(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "rm", "[OPTIONS] CONTAINER", "Remove a container") if err := cmd.Parse(args); err != nil { return nil } for _, name := range cmd.Args() { container := srv.runtime.Get(name) if container == nil { return errors.New("No such container: " + name) } if err := srv.runtime.Destroy(container); err != nil { fmt.Fprintln(stdout, "Error destroying container "+name+": "+err.Error()) } } return nil } // 'docker kill NAME' kills a running container func (srv *Server) CmdKill(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "kill", "[OPTIONS] CONTAINER [CONTAINER...]", "Kill a running container") if err := cmd.Parse(args); err != nil { return nil } for _, name := range cmd.Args() { container := srv.runtime.Get(name) if container == nil { return errors.New("No such container: " + name) } if err := container.Kill(); err != nil { fmt.Fprintln(stdout, "Error killing container "+name+": "+err.Error()) } } return nil } func (srv *Server) CmdImport(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "import", "[OPTIONS] URL|- [REPOSITORY [TAG]]", "Create a new filesystem image from the contents of a tarball") var archive io.Reader var resp *http.Response if err := cmd.Parse(args); err != nil { return nil } src := cmd.Arg(0) if src == "" { return errors.New("Not enough arguments") } else if src == "-" { archive = stdin } else { u, err := url.Parse(src) if err != nil { return err } if u.Scheme == "" { u.Scheme = "http" u.Host = src u.Path = "" } fmt.Fprintf(stdout, "Downloading from %s\n", u.String()) // Download with curl (pretty progress bar) // If curl is not available, fallback to http.Get() resp, err = Download(u.String(), stdout) if err != nil { return err } archive = ProgressReader(resp.Body, int(resp.ContentLength), stdout) } img, err := srv.runtime.graph.Create(archive, nil, "Imported from "+src) if err != nil { return err } // Optionally register the image at REPO/TAG if repository := cmd.Arg(1); repository != "" { tag := cmd.Arg(2) // Repository will handle an empty tag properly if err := srv.runtime.repositories.Set(repository, tag, img.Id, true); err != nil { return err } } fmt.Fprintln(stdout, img.Id) return nil } func (srv *Server) CmdPush(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "push", "NAME", "Push an image or a repository to the registry") if err := cmd.Parse(args); err != nil { return nil } local := cmd.Arg(0) if local == "" { cmd.Usage() return nil } // If the login failed, abort if srv.runtime.authConfig == nil || srv.runtime.authConfig.Username == "" { if err := srv.CmdLogin(stdin, stdout, args...); err != nil { return err } if srv.runtime.authConfig == nil || srv.runtime.authConfig.Username == "" { return fmt.Errorf("Please login prior to push. ('docker login')") } } var remote string tmp := strings.SplitN(local, "/", 2) if len(tmp) == 1 { return fmt.Errorf( "Impossible to push a \"root\" repository. Please rename your repository in / (ex: %s/%s)", srv.runtime.authConfig.Username, local) } else { remote = local } Debugf("Pushing [%s] to [%s]\n", local, remote) // Try to get the image // FIXME: Handle lookup // FIXME: Also push the tags in case of ./docker push myrepo:mytag // img, err := srv.runtime.LookupImage(cmd.Arg(0)) img, err := srv.runtime.graph.Get(local) if err != nil { Debugf("The push refers to a repository [%s] (len: %d)\n", local, len(srv.runtime.repositories.Repositories[local])) // If it fails, try to get the repository if localRepo, exists := srv.runtime.repositories.Repositories[local]; exists { if err := srv.runtime.graph.PushRepository(stdout, remote, localRepo, srv.runtime.authConfig); err != nil { return err } return nil } else { return err } return nil } err = srv.runtime.graph.PushImage(stdout, img, srv.runtime.authConfig) if err != nil { return err } return nil } func (srv *Server) CmdPull(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "pull", "NAME", "Pull an image or a repository from the registry") if err := cmd.Parse(args); err != nil { return nil } remote := cmd.Arg(0) if remote == "" { cmd.Usage() return nil } if srv.runtime.graph.LookupRemoteImage(remote, srv.runtime.authConfig) { fmt.Fprintf(stdout, "Pulling %s...\n", remote) if err := srv.runtime.graph.PullImage(remote, srv.runtime.authConfig); err != nil { return err } fmt.Fprintf(stdout, "Pulled\n") return nil } // FIXME: Allow pull repo:tag fmt.Fprintf(stdout, "Pulling %s...\n", remote) if err := srv.runtime.graph.PullRepository(stdout, remote, "", srv.runtime.repositories, srv.runtime.authConfig); err != nil { return err } fmt.Fprintf(stdout, "Pull completed\n") return nil } func (srv *Server) CmdImages(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "images", "[OPTIONS] [NAME]", "List images") //limit := cmd.Int("l", 0, "Only show the N most recent versions of each image") quiet := cmd.Bool("q", false, "only show numeric IDs") fl_a := cmd.Bool("a", false, "show all images") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() > 1 { cmd.Usage() return nil } var nameFilter string if cmd.NArg() == 1 { nameFilter = cmd.Arg(0) } w := tabwriter.NewWriter(stdout, 20, 1, 3, ' ', 0) if !*quiet { fmt.Fprintf(w, "REPOSITORY\tTAG\tID\tCREATED\tPARENT\n") } var allImages map[string]*Image var err error if *fl_a { allImages, err = srv.runtime.graph.Map() } else { allImages, err = srv.runtime.graph.Heads() } if err != nil { return err } for name, repository := range srv.runtime.repositories.Repositories { if nameFilter != "" && name != nameFilter { continue } for tag, id := range repository { image, err := srv.runtime.graph.Get(id) if err != nil { log.Printf("Warning: couldn't load %s from %s/%s: %s", id, name, tag, err) continue } delete(allImages, id) if !*quiet { for idx, field := range []string{ /* REPOSITORY */ name, /* TAG */ tag, /* ID */ id, /* CREATED */ HumanDuration(time.Now().Sub(image.Created)) + " ago", /* PARENT */ srv.runtime.repositories.ImageName(image.Parent), } { if idx == 0 { w.Write([]byte(field)) } else { w.Write([]byte("\t" + field)) } } w.Write([]byte{'\n'}) } else { stdout.Write([]byte(image.Id + "\n")) } } } // Display images which aren't part of a if nameFilter == "" { for id, image := range allImages { if !*quiet { for idx, field := range []string{ /* REPOSITORY */ "", /* TAG */ "", /* ID */ id, /* CREATED */ HumanDuration(time.Now().Sub(image.Created)) + " ago", /* PARENT */ srv.runtime.repositories.ImageName(image.Parent), } { if idx == 0 { w.Write([]byte(field)) } else { w.Write([]byte("\t" + field)) } } w.Write([]byte{'\n'}) } else { stdout.Write([]byte(image.Id + "\n")) } } } if !*quiet { w.Flush() } return nil } func (srv *Server) CmdPs(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "ps", "[OPTIONS]", "List containers") quiet := cmd.Bool("q", false, "Only display numeric IDs") fl_all := cmd.Bool("a", false, "Show all containers. Only running containers are shown by default.") fl_full := cmd.Bool("notrunc", false, "Don't truncate output") if err := cmd.Parse(args); err != nil { return nil } w := tabwriter.NewWriter(stdout, 12, 1, 3, ' ', 0) if !*quiet { fmt.Fprintf(w, "ID\tIMAGE\tCOMMAND\tCREATED\tSTATUS\tCOMMENT\n") } for _, container := range srv.runtime.List() { if !container.State.Running && !*fl_all { continue } if !*quiet { command := fmt.Sprintf("%s %s", container.Path, strings.Join(container.Args, " ")) if !*fl_full { command = Trunc(command, 20) } for idx, field := range []string{ /* ID */ container.Id, /* IMAGE */ srv.runtime.repositories.ImageName(container.Image), /* COMMAND */ command, /* CREATED */ HumanDuration(time.Now().Sub(container.Created)) + " ago", /* STATUS */ container.State.String(), /* COMMENT */ "", } { if idx == 0 { w.Write([]byte(field)) } else { w.Write([]byte("\t" + field)) } } w.Write([]byte{'\n'}) } else { stdout.Write([]byte(container.Id + "\n")) } } if !*quiet { w.Flush() } return nil } func (srv *Server) CmdCommit(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "commit", "[OPTIONS] CONTAINER [REPOSITORY [TAG]]", "Create a new image from a container's changes") fl_comment := cmd.String("m", "", "Commit message") if err := cmd.Parse(args); err != nil { return nil } containerName, repository, tag := cmd.Arg(0), cmd.Arg(1), cmd.Arg(2) if containerName == "" { cmd.Usage() return nil } img, err := srv.runtime.Commit(containerName, repository, tag, *fl_comment) if err != nil { return err } fmt.Fprintln(stdout, img.Id) return nil } func (srv *Server) CmdExport(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "export", "CONTAINER", "Export the contents of a filesystem as a tar archive") if err := cmd.Parse(args); err != nil { return nil } name := cmd.Arg(0) if container := srv.runtime.Get(name); container != nil { data, err := container.Export() if err != nil { return err } // Stream the entire contents of the container (basically a volatile snapshot) if _, err := io.Copy(stdout, data); err != nil { return err } return nil } return errors.New("No such container: " + name) } func (srv *Server) CmdDiff(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "diff", "CONTAINER [OPTIONS]", "Inspect changes on a container's filesystem") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() < 1 { return errors.New("Not enough arguments") } if container := srv.runtime.Get(cmd.Arg(0)); container == nil { return errors.New("No such container") } else { changes, err := container.Changes() if err != nil { return err } for _, change := range changes { fmt.Fprintln(stdout, change.String()) } } return nil } func (srv *Server) CmdLogs(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "logs", "[OPTIONS] CONTAINER", "Fetch the logs of a container") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() != 1 { cmd.Usage() return nil } name := cmd.Arg(0) if container := srv.runtime.Get(name); container != nil { log_stdout, err := container.ReadLog("stdout") if err != nil { return err } log_stderr, err := container.ReadLog("stderr") if err != nil { return err } // FIXME: Interpolate stdout and stderr instead of concatenating them // FIXME: Differentiate stdout and stderr in the remote protocol if _, err := io.Copy(stdout, log_stdout); err != nil { return err } if _, err := io.Copy(stdout, log_stderr); err != nil { return err } return nil } return errors.New("No such container: " + cmd.Arg(0)) } func (srv *Server) CmdAttach(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "attach", "[OPTIONS]", "Attach to a running container") fl_i := cmd.Bool("i", false, "Attach to stdin") fl_o := cmd.Bool("o", true, "Attach to stdout") fl_e := cmd.Bool("e", true, "Attach to stderr") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() != 1 { cmd.Usage() return nil } name := cmd.Arg(0) container := srv.runtime.Get(name) if container == nil { return errors.New("No such container: " + name) } var wg sync.WaitGroup if *fl_i { c_stdin, err := container.StdinPipe() if err != nil { return err } wg.Add(1) go func() { io.Copy(c_stdin, stdin); wg.Add(-1) }() } if *fl_o { c_stdout, err := container.StdoutPipe() if err != nil { return err } wg.Add(1) go func() { io.Copy(stdout, c_stdout); wg.Add(-1) }() } if *fl_e { c_stderr, err := container.StderrPipe() if err != nil { return err } wg.Add(1) go func() { io.Copy(stdout, c_stderr); wg.Add(-1) }() } wg.Wait() return nil } // Ports type - Used to parse multiple -p flags type ports []int func (p *ports) String() string { return fmt.Sprint(*p) } func (p *ports) Set(value string) error { port, err := strconv.Atoi(value) if err != nil { return fmt.Errorf("Invalid port: %v", value) } *p = append(*p, port) return nil } // ListOpts type type ListOpts []string func (opts *ListOpts) String() string { return fmt.Sprint(*opts) } func (opts *ListOpts) Set(value string) error { *opts = append(*opts, value) return nil } func (srv *Server) CmdTag(stdin io.ReadCloser, stdout io.Writer, args ...string) error { cmd := rcli.Subcmd(stdout, "tag", "[OPTIONS] IMAGE REPOSITORY [TAG]", "Tag an image into a repository") force := cmd.Bool("f", false, "Force") if err := cmd.Parse(args); err != nil { return nil } if cmd.NArg() < 2 { cmd.Usage() return nil } return srv.runtime.repositories.Set(cmd.Arg(1), cmd.Arg(2), cmd.Arg(0), *force) } func (srv *Server) CmdRun(stdin io.ReadCloser, stdout io.Writer, args ...string) error { config, err := ParseRun(args) if err != nil { return err } if config.Image == "" { return fmt.Errorf("Image not specified") } if len(config.Cmd) == 0 { return fmt.Errorf("Command not specified") } // Create new container container, err := srv.runtime.Create(config) if err != nil { return errors.New("Error creating container: " + err.Error()) } if config.OpenStdin { cmd_stdin, err := container.StdinPipe() if err != nil { return err } if !config.Detach { Go(func() error { _, err := io.Copy(cmd_stdin, stdin) cmd_stdin.Close() return err }) } } // Run the container if !config.Detach { cmd_stderr, err := container.StderrPipe() if err != nil { return err } cmd_stdout, err := container.StdoutPipe() if err != nil { return err } if err := container.Start(); err != nil { return err } sending_stdout := Go(func() error { _, err := io.Copy(stdout, cmd_stdout) return err }) sending_stderr := Go(func() error { _, err := io.Copy(stdout, cmd_stderr) return err }) err_sending_stdout := <-sending_stdout err_sending_stderr := <-sending_stderr if err_sending_stdout != nil { return err_sending_stdout } if err_sending_stderr != nil { return err_sending_stderr } container.Wait() } else { if err := container.Start(); err != nil { return err } fmt.Fprintln(stdout, container.Id) } return nil } func NewServer() (*Server, error) { rand.Seed(time.Now().UTC().UnixNano()) if runtime.GOARCH != "amd64" { log.Fatalf("The docker runtime currently only supports amd64 (not %s). This will change in the future. Aborting.", runtime.GOARCH) } runtime, err := NewRuntime() if err != nil { return nil, err } srv := &Server{ runtime: runtime, } return srv, nil } type Server struct { runtime *Runtime }