services/mgmt/node/impl/invoker.go - release.go.x.ref - Git at Google

 package impl

 import (
 	"bytes"
 	"errors"
 	"io"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"reflect"
 	"regexp"
 	"runtime"
 	"strings"
 	"syscall"
 	"time"

 	vexec "veyron/lib/exec"
 	ibuild "veyron/services/mgmt/build"

 	"veyron/services/mgmt/profile"
 	"veyron2/ipc"
 	"veyron2/rt"
 	"veyron2/services/mgmt/application"
 	"veyron2/services/mgmt/build"
 	"veyron2/services/mgmt/content"
 	"veyron2/services/mgmt/node"
 	"veyron2/vlog"
 )

 var updateSuffix = regexp.MustCompile(`^apps\/.*$`)

 // invoker holds the state of a node manager invocation.
 type invoker struct {
 	// envelope is the node manager application envelope.
 	envelope *application.Envelope
 	// origin is a veyron name that resolves to the node manager
 	// envelope.
 	origin string
 	// suffix is the suffix of the current invocation that is assumed to
 	// be used as a relative veyron name to identify an application,
 	// installation, or instance.
 	suffix string
 }

 var (
 	errInvalidSuffix   = errors.New("invalid suffix")
 	errOperationFailed = errors.New("operation failed")
 )

 // NewInvoker is the invoker factory.
 func NewInvoker(envelope *application.Envelope, origin, suffix string) *invoker {
 	return &invoker{
 		envelope: envelope,
 		origin:   origin,
 		suffix:   suffix,
 	}
 }

 // NODE INTERFACE IMPLEMENTATION

 // computeNodeProfile generates a description of the runtime
 // environment (supported file format, OS, architecture, libraries) of
 // the host node.
 //
 // TODO(jsimsa): Avoid computing the host node description from
 // scratch if a recent cached copy exists.
 func (i *invoker) computeNodeProfile() (*profile.Specification, error) {
 	result := profile.Specification{Format: profile.Format{Attributes: make(map[string]string)}}

 	// Find out what the supported file format, operating system, and
 	// architecture is.
 	switch runtime.GOOS {
 	case "linux":
 		result.Format.Name = ibuild.ELF.String()
 		result.Format.Attributes["os"] = ibuild.LINUX.String()
 	case "darwin":
 		result.Format.Name = ibuild.MACH.String()
 		result.Format.Attributes["os"] = ibuild.DARWIN.String()
 	case "windows":
 		result.Format.Name = ibuild.PE.String()
 		result.Format.Attributes["os"] = ibuild.WINDOWS.String()
 	default:
 		return nil, errors.New("Unsupported operating system: " + runtime.GOOS)
 	}
 	switch runtime.GOARCH {
 	case "amd64":
 		result.Format.Attributes["arch"] = ibuild.AMD64.String()
 	case "arm":
 		result.Format.Attributes["arch"] = ibuild.AMD64.String()
 	case "x86":
 		result.Format.Attributes["arch"] = ibuild.AMD64.String()
 	default:
 		return nil, errors.New("Unsupported hardware architecture: " + runtime.GOARCH)
 	}

 	// Find out what the installed dynamically linked libraries are.
 	switch runtime.GOOS {
 	case "linux":
 		// For Linux, we identify what dynamically linked libraries are
 		// install by parsing the output of "ldconfig -p".
 		command := exec.Command("ldconfig", "-p")
 		output, err := command.CombinedOutput()
 		if err != nil {
 			return nil, err
 		}
 		buf := bytes.NewBuffer(output)
 		// Throw away the first line of output from ldconfig.
 		if _, err := buf.ReadString('\n'); err != nil {
 			return nil, errors.New("Could not identify libraries.")
 		}
 		// Extract the library name and version from every subsequent line.
 		result.Libraries = make(map[profile.Library]struct{})
 		line, err := buf.ReadString('\n')
 		for err == nil {
 			words := strings.Split(strings.Trim(line, " \t\n"), " ")
 			if len(words) > 0 {
 				tokens := strings.Split(words[0], ".so")
 				if len(tokens) != 2 {
 					return nil, errors.New("Could not identify library: " + words[0])
 				}
 				name := strings.TrimPrefix(tokens[0], "lib")
 				major, minor := "", ""
 				tokens = strings.SplitN(tokens[1], ".", 3)
 				if len(tokens) >= 2 {
 					major = tokens[1]
 				}
 				if len(tokens) >= 3 {
 					minor = tokens[2]
 				}
 				result.Libraries[profile.Library{Name: name, MajorVersion: major, MinorVersion: minor}] = struct{}{}
 			}
 			line, err = buf.ReadString('\n')
 		}
 	case "darwin":
 		// TODO(jsimsa): Implement.
 	case "windows":
 		// TODO(jsimsa): Implement.
 	default:
 		return nil, errors.New("Unsupported operating system: " + runtime.GOOS)
 	}
 	return &result, nil
 }

 // getProfile gets a profile description for the given profile.
 //
 // TODO(jsimsa): Avoid retrieving the list of known profiles from a
 // remote server if a recent cached copy exists.
 func (i *invoker) getProfile(name string) (*profile.Specification, error) {
 	// TODO(jsimsa): This function assumes the existence of a profile
 	// server from which the profiles can be retrieved. The profile
 	// server is a work in progress. When it exists, the commented out
 	// code below should work.
 	var profile profile.Specification
 	/*
 			client, err := r.NewClient()
 			if err != nil {
 				vlog.Errorf("NewClient() failed: %v", err)
 				return nil, err
 			}
 			defer client.Close()
 		  server := // TODO
 			method := "Specification"
 			inputs := make([]interface{}, 0)
 			call, err := client.StartCall(server + "/" + name, method, inputs)
 			if err != nil {
 				vlog.Errorf("StartCall(%s, %q, %v) failed: %v\n", server + "/" + name, method, inputs, err)
 				return nil, err
 			}
 			if err := call.Finish(&profiles); err != nil {
 				vlog.Errorf("Finish(%v) failed: %v\n", &profiles, err)
 				return nil, err
 			}
 	*/
 	return &profile, nil
 }

 // getKnownProfiles gets a list of description for all publicly known
 // profiles.
 //
 // TODO(jsimsa): Avoid retrieving the list of known profiles from a
 // remote server if a recent cached copy exists.
 func (i *invoker) getKnownProfiles() ([]profile.Specification, error) {
 	// TODO(jsimsa): This function assumes the existence of a profile
 	// server from which a list of known profiles can be retrieved. The
 	// profile server is a work in progress. When it exists, the
 	// commented out code below should work.
 	knownProfiles := make([]profile.Specification, 0)
 	/*
 			client, err := r.NewClient()
 			if err != nil {
 				vlog.Errorf("NewClient() failed: %v\n", err)
 				return nil, err
 			}
 			defer client.Close()
 		  server := // TODO
 			method := "List"
 			inputs := make([]interface{}, 0)
 			call, err := client.StartCall(server, method, inputs)
 			if err != nil {
 				vlog.Errorf("StartCall(%s, %q, %v) failed: %v\n", server, method, inputs, err)
 				return nil, err
 			}
 			if err := call.Finish(&knownProfiles); err != nil {
 				vlog.Errorf("Finish(&knownProfile) failed: %v\n", err)
 				return nil, err
 			}
 	*/
 	return knownProfiles, nil
 }

 // matchProfiles inputs a profile that describes the host node and a
 // set of publicly known profiles and outputs a node description that
 // identifies the publicly known profiles supported by the host node.
 func (i *invoker) matchProfiles(p *profile.Specification, known []profile.Specification) node.Description {
 	result := node.Description{Profiles: make(map[string]struct{})}
 loop:
 	for _, profile := range known {
 		if profile.Format.Name != p.Format.Name {
 			continue
 		}
 		if profile.Format.Attributes["os"] != p.Format.Attributes["os"] {
 			continue
 		}
 		if profile.Format.Attributes["arch"] != p.Format.Attributes["arch"] {
 			continue
 		}
 		for library := range profile.Libraries {
 			// Current implementation requires exact library name and version match.
 			if _, found := p.Libraries[library]; !found {
 				continue loop
 			}
 		}
 		result.Profiles[profile.Label] = struct{}{}
 	}
 	return result
 }

 func (i *invoker) Describe(call ipc.ServerContext) (node.Description, error) {
 	vlog.VI(0).Infof("%v.Describe()", i.suffix)
 	empty := node.Description{}
 	nodeProfile, err := i.computeNodeProfile()
 	if err != nil {
 		return empty, err
 	}
 	knownProfiles, err := i.getKnownProfiles()
 	if err != nil {
 		return empty, err
 	}
 	result := i.matchProfiles(nodeProfile, knownProfiles)
 	return result, nil
 }

 func (i *invoker) IsRunnable(call ipc.ServerContext, binary build.BinaryDescription) (bool, error) {
 	vlog.VI(0).Infof("%v.IsRunnable(%v)", i.suffix, binary)
 	nodeProfile, err := i.computeNodeProfile()
 	if err != nil {
 		return false, err
 	}
 	binaryProfiles := make([]profile.Specification, 0)
 	for name, _ := range binary.Profiles {
 		profile, err := i.getProfile(name)
 		if err != nil {
 			return false, err
 		}
 		binaryProfiles = append(binaryProfiles, *profile)
 	}
 	result := i.matchProfiles(nodeProfile, binaryProfiles)
 	return len(result.Profiles) > 0, nil
 }

 func (i *invoker) Reset(call ipc.ServerContext, deadline uint64) error {
 	vlog.VI(0).Infof("%v.Reset(%v)", i.suffix, deadline)
 	// TODO(jsimsa): Implement.
 	return nil
 }

 // APPLICATION INTERFACE IMPLEMENTATION

 func downloadBinary(binary string) (string, error) {
 	stub, err := content.BindContent(binary)
 	if err != nil {
 		vlog.Errorf("BindContent(%q) failed: %v", binary, err)
 		return "", errOperationFailed
 	}
 	stream, err := stub.Download(rt.R().NewContext())
 	if err != nil {
 		vlog.Errorf("Download() failed: %v", err)
 		return "", errOperationFailed
 	}
 	tmpDir, prefix := "", ""
 	file, err := ioutil.TempFile(tmpDir, prefix)
 	if err != nil {
 		vlog.Errorf("TempFile(%q, %q) failed: %v", tmpDir, prefix, err)
 		return "", errOperationFailed
 	}
 	defer file.Close()
 	for {
 		bytes, err := stream.Recv()
 		if err == io.EOF {
 			break
 		}
 		if err != nil {
 			vlog.Errorf("Recv() failed: %v", err)
 			os.Remove(file.Name())
 			return "", errOperationFailed
 		}
 		if _, err := file.Write(bytes); err != nil {
 			vlog.Errorf("Write() failed: %v", err)
 			os.Remove(file.Name())
 			return "", errOperationFailed
 		}
 	}
 	if err := stream.Finish(); err != nil {
 		vlog.Errorf("Finish() failed: %v", err)
 		os.Remove(file.Name())
 		return "", errOperationFailed
 	}
 	mode := os.FileMode(0755)
 	if err := file.Chmod(mode); err != nil {
 		vlog.Errorf("Chmod(%v) failed: %v", mode, err)
 		os.Remove(file.Name())
 		return "", errOperationFailed
 	}
 	return file.Name(), nil
 }

 func fetchEnvelope(origin string) (*application.Envelope, error) {
 	stub, err := application.BindRepository(origin)
 	if err != nil {
 		vlog.Errorf("BindRepository(%v) failed: %v", origin, err)
 		return nil, errOperationFailed
 	}
 	// TODO(jsimsa): Include logic that computes the set of supported
 	// profiles.
 	profiles := []string{"test"}
 	envelope, err := stub.Match(rt.R().NewContext(), profiles)
 	if err != nil {
 		vlog.Errorf("Match(%v) failed: %v", profiles, err)
 		return nil, errOperationFailed
 	}
 	return &envelope, nil
 }

 func replaceBinary(oldBinary, newBinary string) error {
 	// Replace the old binary with the new one.
 	if err := syscall.Unlink(oldBinary); err != nil {
 		vlog.Errorf("Unlink(%v) failed: %v", oldBinary, err)
 		return errOperationFailed
 	}
 	if err := os.Rename(newBinary, oldBinary); err != nil {
 		vlog.Errorf("Rename(%v, %v) failed: %v", newBinary, oldBinary, err)
 		return errOperationFailed
 	}
 	return nil
 }

 func spawnNodeManager(envelope *application.Envelope) error {
 	cmd := exec.Command(os.Args[0], envelope.Args...)
 	cmd.Env = envelope.Env
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr

 	handle := vexec.NewParentHandle(cmd)
 	if err := handle.Start(); err != nil {
 		vlog.Errorf("Start() failed: %v", err)
 		return errOperationFailed
 	}
 	if err := handle.WaitForReady(10 * time.Second); err != nil {
 		vlog.Errorf("WaitForReady() failed: %v", err)
 		cmd.Process.Kill()
 		return errOperationFailed
 	}
 	rt.R().Stop()
 	return nil
 }

 func (i *invoker) Install(call ipc.ServerContext) (string, error) {
 	vlog.VI(0).Infof("%v.Install()", i.suffix)
 	// TODO(jsimsa): Implement.
 	return "", nil
 }

 func (i *invoker) Start(call ipc.ServerContext) ([]string, error) {
 	vlog.VI(0).Infof("%v.Start()", i.suffix)
 	// TODO(jsimsa): Implement.
 	return make([]string, 0), nil
 }

 func (i *invoker) Uninstall(call ipc.ServerContext) error {
 	vlog.VI(0).Infof("%v.Uninstall()", i.suffix)
 	// TODO(jsimsa): Implement.
 	return nil
 }

 func (i *invoker) Update(call ipc.ServerContext) error {
 	vlog.VI(0).Infof("%v.Update()", i.suffix)
 	switch {
 	case i.suffix == "nm":
 		// This branch attempts to update the node manager updates itself.
 		envelope, err := fetchEnvelope(i.origin)
 		if err != nil {
 			return err
 		}
 		if envelope.Binary != i.envelope.Binary {
 			file, err := downloadBinary(envelope.Binary)
 			if err != nil {
 				return err
 			}
 			if err := replaceBinary(os.Args[0], file); err != nil {
 				os.Remove(file)
 				return err
 			}
 		}
 		if !reflect.DeepEqual(envelope, i.envelope) {
 			i.envelope = envelope
 			if err := spawnNodeManager(i.envelope); err != nil {
 				return err
 			}
 			// TODO(jsimsa): When Bogdan implements the shutdown API, use it
 			// to stop itself (or have the caller do that).
 		}
 		return nil
 	case updateSuffix.MatchString(i.suffix):
 		// TODO(jsimsa): Implement.
 		return nil
 	default:
 		return errInvalidSuffix
 	}
 }

 func (i *invoker) Refresh(call ipc.ServerContext) error {
 	vlog.VI(0).Infof("%v.Refresh()", i.suffix)
 	// TODO(jsimsa): Implement.
 	return nil
 }

 func (i *invoker) Restart(call ipc.ServerContext) error {
 	vlog.VI(0).Infof("%v.Restart()", i.suffix)
 	// TODO(jsimsa): Implement.
 	return nil
 }

 func (i *invoker) Resume(call ipc.ServerContext) error {
 	vlog.VI(0).Infof("%v.Resume()", i.suffix)
 	// TODO(jsimsa): Implement.
 	return nil
 }

 func (i *invoker) Shutdown(call ipc.ServerContext, deadline uint64) error {
 	vlog.VI(0).Infof("%v.Shutdown(%v)", i.suffix, deadline)
 	// TODO(jsimsa): Implement.
 	return nil
 }

 func (i *invoker) Suspend(call ipc.ServerContext) error {
 	vlog.VI(0).Infof("%v.Suspend()", i.suffix)
 	// TODO(jsimsa): Implement.
 	return nil
 }
	package impl

	import (
	"bytes"
	"errors"
	"io"
	"io/ioutil"
	"os"
	"os/exec"
	"reflect"
	"regexp"
	"runtime"
	"strings"
	"syscall"
	"time"

	vexec "veyron/lib/exec"
	ibuild "veyron/services/mgmt/build"

	"veyron/services/mgmt/profile"
	"veyron2/ipc"
	"veyron2/rt"
	"veyron2/services/mgmt/application"
	"veyron2/services/mgmt/build"
	"veyron2/services/mgmt/content"
	"veyron2/services/mgmt/node"
	"veyron2/vlog"
	)

	var updateSuffix = regexp.MustCompile(`^apps\/.*$`)

	// invoker holds the state of a node manager invocation.
	type invoker struct {
	// envelope is the node manager application envelope.
	envelope *application.Envelope
	// origin is a veyron name that resolves to the node manager
	// envelope.
	origin string
	// suffix is the suffix of the current invocation that is assumed to
	// be used as a relative veyron name to identify an application,
	// installation, or instance.
	suffix string
	}

	var (
	errInvalidSuffix = errors.New("invalid suffix")
	errOperationFailed = errors.New("operation failed")
	)

	// NewInvoker is the invoker factory.
	func NewInvoker(envelope application.Envelope, origin, suffix string) invoker {
	return &invoker{
	envelope: envelope,
	origin: origin,
	suffix: suffix,
	}
	}

	// NODE INTERFACE IMPLEMENTATION

	// computeNodeProfile generates a description of the runtime
	// environment (supported file format, OS, architecture, libraries) of
	// the host node.
	//
	// TODO(jsimsa): Avoid computing the host node description from
	// scratch if a recent cached copy exists.
	func (i invoker) computeNodeProfile() (profile.Specification, error) {
	result := profile.Specification{Format: profile.Format{Attributes: make(map[string]string)}}

	// Find out what the supported file format, operating system, and
	// architecture is.
	switch runtime.GOOS {
	case "linux":
	result.Format.Name = ibuild.ELF.String()
	result.Format.Attributes["os"] = ibuild.LINUX.String()
	case "darwin":
	result.Format.Name = ibuild.MACH.String()
	result.Format.Attributes["os"] = ibuild.DARWIN.String()
	case "windows":
	result.Format.Name = ibuild.PE.String()
	result.Format.Attributes["os"] = ibuild.WINDOWS.String()
	default:
	return nil, errors.New("Unsupported operating system: " + runtime.GOOS)
	}
	switch runtime.GOARCH {
	case "amd64":
	result.Format.Attributes["arch"] = ibuild.AMD64.String()
	case "arm":
	result.Format.Attributes["arch"] = ibuild.AMD64.String()
	case "x86":
	result.Format.Attributes["arch"] = ibuild.AMD64.String()
	default:
	return nil, errors.New("Unsupported hardware architecture: " + runtime.GOARCH)
	}

	// Find out what the installed dynamically linked libraries are.
	switch runtime.GOOS {
	case "linux":
	// For Linux, we identify what dynamically linked libraries are
	// install by parsing the output of "ldconfig -p".
	command := exec.Command("ldconfig", "-p")
	output, err := command.CombinedOutput()
	if err != nil {
	return nil, err
	}
	buf := bytes.NewBuffer(output)
	// Throw away the first line of output from ldconfig.
	if _, err := buf.ReadString('\n'); err != nil {
	return nil, errors.New("Could not identify libraries.")
	}
	// Extract the library name and version from every subsequent line.
	result.Libraries = make(map[profile.Library]struct{})
	line, err := buf.ReadString('\n')
	for err == nil {
	words := strings.Split(strings.Trim(line, " \t\n"), " ")
	if len(words) > 0 {
	tokens := strings.Split(words[0], ".so")
	if len(tokens) != 2 {
	return nil, errors.New("Could not identify library: " + words[0])
	}
	name := strings.TrimPrefix(tokens[0], "lib")
	major, minor := "", ""
	tokens = strings.SplitN(tokens[1], ".", 3)
	if len(tokens) >= 2 {
	major = tokens[1]
	}
	if len(tokens) >= 3 {
	minor = tokens[2]
	}
	result.Libraries[profile.Library{Name: name, MajorVersion: major, MinorVersion: minor}] = struct{}{}
	}
	line, err = buf.ReadString('\n')
	}
	case "darwin":
	// TODO(jsimsa): Implement.
	case "windows":
	// TODO(jsimsa): Implement.
	default:
	return nil, errors.New("Unsupported operating system: " + runtime.GOOS)
	}
	return &result, nil
	}

	// getProfile gets a profile description for the given profile.
	//
	// TODO(jsimsa): Avoid retrieving the list of known profiles from a
	// remote server if a recent cached copy exists.
	func (i invoker) getProfile(name string) (profile.Specification, error) {
	// TODO(jsimsa): This function assumes the existence of a profile
	// server from which the profiles can be retrieved. The profile
	// server is a work in progress. When it exists, the commented out
	// code below should work.
	var profile profile.Specification
	/*
	client, err := r.NewClient()
	if err != nil {
	vlog.Errorf("NewClient() failed: %v", err)
	return nil, err
	}
	defer client.Close()
	server := // TODO
	method := "Specification"
	inputs := make([]interface{}, 0)
	call, err := client.StartCall(server + "/" + name, method, inputs)
	if err != nil {
	vlog.Errorf("StartCall(%s, %q, %v) failed: %v\n", server + "/" + name, method, inputs, err)
	return nil, err
	}
	if err := call.Finish(&profiles); err != nil {
	vlog.Errorf("Finish(%v) failed: %v\n", &profiles, err)
	return nil, err
	}
	*/
	return &profile, nil
	}

	// getKnownProfiles gets a list of description for all publicly known
	// profiles.
	//
	// TODO(jsimsa): Avoid retrieving the list of known profiles from a
	// remote server if a recent cached copy exists.
	func (i *invoker) getKnownProfiles() ([]profile.Specification, error) {
	// TODO(jsimsa): This function assumes the existence of a profile
	// server from which a list of known profiles can be retrieved. The
	// profile server is a work in progress. When it exists, the
	// commented out code below should work.
	knownProfiles := make([]profile.Specification, 0)
	/*
	client, err := r.NewClient()
	if err != nil {
	vlog.Errorf("NewClient() failed: %v\n", err)
	return nil, err
	}
	defer client.Close()
	server := // TODO
	method := "List"
	inputs := make([]interface{}, 0)
	call, err := client.StartCall(server, method, inputs)
	if err != nil {
	vlog.Errorf("StartCall(%s, %q, %v) failed: %v\n", server, method, inputs, err)
	return nil, err
	}
	if err := call.Finish(&knownProfiles); err != nil {
	vlog.Errorf("Finish(&knownProfile) failed: %v\n", err)
	return nil, err
	}
	*/
	return knownProfiles, nil
	}

	// matchProfiles inputs a profile that describes the host node and a
	// set of publicly known profiles and outputs a node description that
	// identifies the publicly known profiles supported by the host node.
	func (i invoker) matchProfiles(p profile.Specification, known []profile.Specification) node.Description {
	result := node.Description{Profiles: make(map[string]struct{})}
	loop:
	for _, profile := range known {
	if profile.Format.Name != p.Format.Name {
	continue
	}
	if profile.Format.Attributes["os"] != p.Format.Attributes["os"] {
	continue
	}
	if profile.Format.Attributes["arch"] != p.Format.Attributes["arch"] {
	continue
	}
	for library := range profile.Libraries {
	// Current implementation requires exact library name and version match.
	if _, found := p.Libraries[library]; !found {
	continue loop
	}
	}
	result.Profiles[profile.Label] = struct{}{}
	}
	return result
	}

	func (i *invoker) Describe(call ipc.ServerContext) (node.Description, error) {
	vlog.VI(0).Infof("%v.Describe()", i.suffix)
	empty := node.Description{}
	nodeProfile, err := i.computeNodeProfile()
	if err != nil {
	return empty, err
	}
	knownProfiles, err := i.getKnownProfiles()
	if err != nil {
	return empty, err
	}
	result := i.matchProfiles(nodeProfile, knownProfiles)
	return result, nil
	}

	func (i *invoker) IsRunnable(call ipc.ServerContext, binary build.BinaryDescription) (bool, error) {
	vlog.VI(0).Infof("%v.IsRunnable(%v)", i.suffix, binary)
	nodeProfile, err := i.computeNodeProfile()
	if err != nil {
	return false, err
	}
	binaryProfiles := make([]profile.Specification, 0)
	for name, _ := range binary.Profiles {
	profile, err := i.getProfile(name)
	if err != nil {
	return false, err
	}
	binaryProfiles = append(binaryProfiles, *profile)
	}
	result := i.matchProfiles(nodeProfile, binaryProfiles)
	return len(result.Profiles) > 0, nil
	}

	func (i *invoker) Reset(call ipc.ServerContext, deadline uint64) error {
	vlog.VI(0).Infof("%v.Reset(%v)", i.suffix, deadline)
	// TODO(jsimsa): Implement.
	return nil
	}

	// APPLICATION INTERFACE IMPLEMENTATION

	func downloadBinary(binary string) (string, error) {
	stub, err := content.BindContent(binary)
	if err != nil {
	vlog.Errorf("BindContent(%q) failed: %v", binary, err)
	return "", errOperationFailed
	}
	stream, err := stub.Download(rt.R().NewContext())
	if err != nil {
	vlog.Errorf("Download() failed: %v", err)
	return "", errOperationFailed
	}
	tmpDir, prefix := "", ""
	file, err := ioutil.TempFile(tmpDir, prefix)
	if err != nil {
	vlog.Errorf("TempFile(%q, %q) failed: %v", tmpDir, prefix, err)
	return "", errOperationFailed
	}
	defer file.Close()
	for {
	bytes, err := stream.Recv()
	if err == io.EOF {
	break
	}
	if err != nil {
	vlog.Errorf("Recv() failed: %v", err)
	os.Remove(file.Name())
	return "", errOperationFailed
	}
	if _, err := file.Write(bytes); err != nil {
	vlog.Errorf("Write() failed: %v", err)
	os.Remove(file.Name())
	return "", errOperationFailed
	}
	}
	if err := stream.Finish(); err != nil {
	vlog.Errorf("Finish() failed: %v", err)
	os.Remove(file.Name())
	return "", errOperationFailed
	}
	mode := os.FileMode(0755)
	if err := file.Chmod(mode); err != nil {
	vlog.Errorf("Chmod(%v) failed: %v", mode, err)
	os.Remove(file.Name())
	return "", errOperationFailed
	}
	return file.Name(), nil
	}

	func fetchEnvelope(origin string) (*application.Envelope, error) {
	stub, err := application.BindRepository(origin)
	if err != nil {
	vlog.Errorf("BindRepository(%v) failed: %v", origin, err)
	return nil, errOperationFailed
	}
	// TODO(jsimsa): Include logic that computes the set of supported
	// profiles.
	profiles := []string{"test"}
	envelope, err := stub.Match(rt.R().NewContext(), profiles)
	if err != nil {
	vlog.Errorf("Match(%v) failed: %v", profiles, err)
	return nil, errOperationFailed
	}
	return &envelope, nil
	}

	func replaceBinary(oldBinary, newBinary string) error {
	// Replace the old binary with the new one.
	if err := syscall.Unlink(oldBinary); err != nil {
	vlog.Errorf("Unlink(%v) failed: %v", oldBinary, err)
	return errOperationFailed
	}
	if err := os.Rename(newBinary, oldBinary); err != nil {
	vlog.Errorf("Rename(%v, %v) failed: %v", newBinary, oldBinary, err)
	return errOperationFailed
	}
	return nil
	}

	func spawnNodeManager(envelope *application.Envelope) error {
	cmd := exec.Command(os.Args[0], envelope.Args...)
	cmd.Env = envelope.Env
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	handle := vexec.NewParentHandle(cmd)
	if err := handle.Start(); err != nil {
	vlog.Errorf("Start() failed: %v", err)
	return errOperationFailed
	}
	if err := handle.WaitForReady(10 * time.Second); err != nil {
	vlog.Errorf("WaitForReady() failed: %v", err)
	cmd.Process.Kill()
	return errOperationFailed
	}
	rt.R().Stop()
	return nil
	}

	func (i *invoker) Install(call ipc.ServerContext) (string, error) {
	vlog.VI(0).Infof("%v.Install()", i.suffix)
	// TODO(jsimsa): Implement.
	return "", nil
	}

	func (i *invoker) Start(call ipc.ServerContext) ([]string, error) {
	vlog.VI(0).Infof("%v.Start()", i.suffix)
	// TODO(jsimsa): Implement.
	return make([]string, 0), nil
	}

	func (i *invoker) Uninstall(call ipc.ServerContext) error {
	vlog.VI(0).Infof("%v.Uninstall()", i.suffix)
	// TODO(jsimsa): Implement.
	return nil
	}

	func (i *invoker) Update(call ipc.ServerContext) error {
	vlog.VI(0).Infof("%v.Update()", i.suffix)
	switch {
	case i.suffix == "nm":
	// This branch attempts to update the node manager updates itself.
	envelope, err := fetchEnvelope(i.origin)
	if err != nil {
	return err
	}
	if envelope.Binary != i.envelope.Binary {
	file, err := downloadBinary(envelope.Binary)
	if err != nil {
	return err
	}
	if err := replaceBinary(os.Args[0], file); err != nil {
	os.Remove(file)
	return err
	}
	}
	if !reflect.DeepEqual(envelope, i.envelope) {
	i.envelope = envelope
	if err := spawnNodeManager(i.envelope); err != nil {
	return err
	}
	// TODO(jsimsa): When Bogdan implements the shutdown API, use it
	// to stop itself (or have the caller do that).
	}
	return nil
	case updateSuffix.MatchString(i.suffix):
	// TODO(jsimsa): Implement.
	return nil
	default:
	return errInvalidSuffix
	}
	}

	func (i *invoker) Refresh(call ipc.ServerContext) error {
	vlog.VI(0).Infof("%v.Refresh()", i.suffix)
	// TODO(jsimsa): Implement.
	return nil
	}

	func (i *invoker) Restart(call ipc.ServerContext) error {
	vlog.VI(0).Infof("%v.Restart()", i.suffix)
	// TODO(jsimsa): Implement.
	return nil
	}

	func (i *invoker) Resume(call ipc.ServerContext) error {
	vlog.VI(0).Infof("%v.Resume()", i.suffix)
	// TODO(jsimsa): Implement.
	return nil
	}

	func (i *invoker) Shutdown(call ipc.ServerContext, deadline uint64) error {
	vlog.VI(0).Infof("%v.Shutdown(%v)", i.suffix, deadline)
	// TODO(jsimsa): Implement.
	return nil
	}

	func (i *invoker) Suspend(call ipc.ServerContext) error {
	vlog.VI(0).Infof("%v.Suspend()", i.suffix)
	// TODO(jsimsa): Implement.
	return nil
	}