lib/flags/flags.go - release.go.x.ref - Git at Google

 package flags

 import (
 	"flag"
 	"fmt"
 	"os"
 	"strings"
 	"sync"

 	"v.io/x/ref/lib/flags/buildinfo"
 	"v.io/x/ref/lib/flags/consts"
 )

 // FlagGroup is the type for identifying groups of related flags.
 type FlagGroup int

 const (
 	// Runtime identifies the flags and associated environment variables
 	// used by the Vanadium process runtime. Namely:
 	// --veyron.namespace.root (which may be repeated to supply multiple values)
 	// --veyron.credentials
 	// --veyron.vtrace.sample_rate
 	// --veyron.vtrace.dump_on_shutdown
 	// --veyron.vtrace.cache_size
 	// --veyron.vtrace.collect_regexp
 	Runtime FlagGroup = iota
 	// Listen identifies the flags typically required to configure
 	// ipc.ListenSpec. Namely:
 	// --veyron.tcp.protocol
 	// --veyron.tcp.address
 	// --veyron.proxy
 	// --vanadium.i18n_catalogue
 	Listen
 	// --veyron.acl.file (which may be repeated to supply multiple values)
 	// ACL files are named - i.e. --veyron.acl=<name>:<file> with the
 	// name <runtime> reserved for use by the runtime.
 	// --veyron.acl.literal
 	ACL
 )

 const defaultNamespaceRoot = "/ns.dev.v.io:8101"

 // Flags represents the set of flag groups created by a call to
 // CreateAndRegister.
 type Flags struct {
 	FlagSet *flag.FlagSet
 	groups  map[FlagGroup]interface{}
 }

 type namespaceRootFlagVar struct {
 	isSet bool // is true when a flag has been explicitly set.
 	roots []string
 }

 func (nsr *namespaceRootFlagVar) String() string {
 	return fmt.Sprintf("%v", nsr.roots)
 }

 func (nsr *namespaceRootFlagVar) Set(v string) error {
 	if !nsr.isSet {
 		// override the default value
 		nsr.isSet = true
 		nsr.roots = []string{}
 	}
 	for _, t := range nsr.roots {
 		if v == t {
 			return nil
 		}
 	}
 	nsr.roots = append(nsr.roots, v)
 	return nil
 }

 type aclFlagVar struct {
 	isSet bool
 	files map[string]string
 }

 func (aclf *aclFlagVar) String() string {
 	return fmt.Sprintf("%v", aclf.files)
 }

 func (aclf *aclFlagVar) Set(v string) error {
 	if !aclf.isSet {
 		// override the default value
 		aclf.isSet = true
 		aclf.files = make(map[string]string)
 	}
 	parts := strings.SplitN(v, ":", 2)
 	if len(parts) != 2 {
 		return fmt.Errorf("%q is not in 'name:file' format", v)
 	}
 	name, file := parts[0], parts[1]
 	aclf.files[name] = file
 	return nil
 }

 // RuntimeFlags contains the values of the Runtime flag group.
 type RuntimeFlags struct {
 	// NamespaceRoots may be initialized by NAMESPACE_ROOT* enivornment
 	// variables as well as --veyron.namespace.root. The command line
 	// will override the environment.
 	NamespaceRoots []string // TODO(cnicolaou): provide flag.Value impl

 	// Credentials may be initialized by the VEYRON_CREDENTIALS
 	// environment variable. The command line will override the environment.
 	Credentials string // TODO(cnicolaou): provide flag.Value impl

 	// I18nCatalogue may be initialized by the VANADIUM_I18N_CATALOGUE
 	// environment variable.  The command line will override the
 	// environment.
 	I18nCatalogue string

 	// Vtrace flags control various aspects of Vtrace.
 	Vtrace VtraceFlags

 	namespaceRootsFlag namespaceRootFlagVar
 }

 type VtraceFlags struct {
 	// VtraceSampleRate is the rate (from 0.0 - 1.0) at which
 	// vtrace traces started by this process are sampled for collection.
 	SampleRate float64

 	// VtraceDumpOnShutdown tells the runtime to dump all stored traces
 	// to Stderr at shutdown if true.
 	DumpOnShutdown bool

 	// VtraceCacheSize is the number of traces to cache in memory.
 	// TODO(mattr): Traces can be of widely varying size, we should have
 	// some better measurement then just number of traces.
 	CacheSize int

 	// SpanRegexp matches a regular expression against span names and
 	// annotations and forces any trace matching trace to be collected.
 	CollectRegexp string
 }

 // ACLFlags contains the values of the ACLFlags flag group.
 type ACLFlags struct {
 	// List of named ACL files.
 	fileFlag aclFlagVar

 	// Single json string, overrides everything.
 	literal string
 }

 // ACLFile returns the file which is presumed to contain ACL information
 // associated with the supplied name parameter.
 func (af ACLFlags) ACLFile(name string) string {
 	return af.fileFlag.files[name]
 }

 func (af ACLFlags) ACLLiteral() string {
 	return af.literal
 }

 // ListenAddrs is the set of listen addresses captured from the command line.
 // ListenAddrs mirrors ipc.ListenAddrs.
 type ListenAddrs []struct {
 	Protocol, Address string
 }

 // ListenFlags contains the values of the Listen flag group.
 type ListenFlags struct {
 	Addrs       ListenAddrs
 	ListenProxy string
 	protocol    TCPProtocolFlag
 	addresses   ipHostPortFlagVar
 }

 type ipHostPortFlagVar struct {
 	validator IPHostPortFlag
 	flags     *ListenFlags
 }

 // Implements flag.Value.Get
 func (ip ipHostPortFlagVar) Get() interface{} {
 	return ip.String()
 }

 // Implements flag.Value.Set
 func (ip *ipHostPortFlagVar) Set(s string) error {
 	if err := ip.validator.Set(s); err != nil {
 		return err
 	}
 	a := struct {
 		Protocol, Address string
 	}{
 		ip.flags.protocol.String(),
 		ip.validator.String(),
 	}
 	for _, t := range ip.flags.Addrs {
 		if t.Protocol == a.Protocol && t.Address == a.Address {
 			return nil
 		}
 	}
 	ip.flags.Addrs = append(ip.flags.Addrs, a)
 	return nil
 }

 // Implements flag.Value.String
 func (ip ipHostPortFlagVar) String() string {
 	s := ""
 	for _, a := range ip.flags.Addrs {
 		s += fmt.Sprintf("(%s %s)", a.Protocol, a.Address)
 	}
 	return s
 }

 // createAndRegisterRuntimeFlags creates and registers the RuntimeFlags
 // group with the supplied flag.FlagSet.
 func createAndRegisterRuntimeFlags(fs *flag.FlagSet) *RuntimeFlags {
 	f := &RuntimeFlags{}
 	roots, creds, i18nCatalogue := readEnv()
 	if len(roots) == 0 {
 		f.namespaceRootsFlag.roots = []string{defaultNamespaceRoot}
 	} else {
 		f.namespaceRootsFlag.roots = roots
 	}

 	fs.Var(&f.namespaceRootsFlag, "veyron.namespace.root", "local namespace root; can be repeated to provided multiple roots")
 	fs.StringVar(&f.Credentials, "veyron.credentials", creds, "directory to use for storing security credentials")
 	fs.StringVar(&f.I18nCatalogue, "vanadium.i18n_catalogue", i18nCatalogue, "18n catalogue files to load, comma separated")

 	fs.Float64Var(&f.Vtrace.SampleRate, "veyron.vtrace.sample_rate", 0.0, "Rate (from 0.0 to 1.0) to sample vtrace traces.")
 	fs.BoolVar(&f.Vtrace.DumpOnShutdown, "veyron.vtrace.dump_on_shutdown", true, "If true, dump all stored traces on runtime shutdown.")
 	fs.IntVar(&f.Vtrace.CacheSize, "veyron.vtrace.cache_size", 1024, "The number of vtrace traces to store in memory.")
 	fs.StringVar(&f.Vtrace.CollectRegexp, "veyron.vtrace.collect_regexp", "", "Spans and annotations that match this regular expression will trigger trace collection.")

 	return f
 }

 func createAndRegisterACLFlags(fs *flag.FlagSet) *ACLFlags {
 	f := &ACLFlags{}
 	fs.Var(&f.fileFlag, "veyron.acl.file", "specify an acl file as <name>:<aclfile>")
 	fs.StringVar(&f.literal, "veyron.acl.literal", "", "explicitly specify the runtime acl as a JSON-encoded access.TaggedACLMap. Overrides all --veyron.acl.file flags.")
 	return f
 }

 var (
 	defaultProtocol = "wsh" // GUARDED_BY listenMu
 	defaultHostPort = ":0"  // GUARDED_BY listenMu
 	listenMu        sync.RWMutex
 )

 // SetDefaultProtocol sets the default protocol used when --veyron.tcp.protocol is
 // not provided. It must be called before flags are parsed for it to take effect.
 func SetDefaultProtocol(protocol string) {
 	listenMu.Lock()
 	defaultProtocol = protocol
 	listenMu.Unlock()
 }

 // SetDefaultHostPort sets the default host and port used when --veyron.tcp.address
 // is not provided. It must be called before flags are parsed for it to take effect.
 func SetDefaultHostPort(s string) {
 	listenMu.Lock()
 	defaultHostPort = s
 	listenMu.Unlock()
 }

 // createAndRegisterListenFlags creates and registers the ListenFlags
 // group with the supplied flag.FlagSet.
 func createAndRegisterListenFlags(fs *flag.FlagSet) *ListenFlags {
 	listenMu.RLock()
 	defer listenMu.RUnlock()
 	var ipHostPortFlag IPHostPortFlag
 	if err := ipHostPortFlag.Set(defaultHostPort); err != nil {
 		panic(err)
 	}
 	f := &ListenFlags{
 		protocol:  TCPProtocolFlag{defaultProtocol},
 		addresses: ipHostPortFlagVar{validator: ipHostPortFlag},
 	}
 	f.addresses.flags = f

 	fs.Var(&f.protocol, "veyron.tcp.protocol", "protocol to listen with")
 	fs.Var(&f.addresses, "veyron.tcp.address", "address to listen on")
 	fs.StringVar(&f.ListenProxy, "veyron.proxy", "", "object name of proxy service to use to export services across network boundaries")
 	return f
 }

 // CreateAndRegister creates a new set of flag groups as specified by the
 // supplied flag group parameters and registers them with the supplied
 // flag.FlagSet.
 func CreateAndRegister(fs *flag.FlagSet, groups ...FlagGroup) *Flags {
 	if len(groups) == 0 {
 		return nil
 	}
 	f := &Flags{FlagSet: fs, groups: make(map[FlagGroup]interface{})}
 	for _, g := range groups {
 		switch g {
 		case Runtime:
 			f.groups[Runtime] = createAndRegisterRuntimeFlags(fs)
 		case Listen:
 			f.groups[Listen] = createAndRegisterListenFlags(fs)
 		case ACL:
 			f.groups[ACL] = createAndRegisterACLFlags(fs)
 		}
 	}
 	return f
 }

 // RuntimeFlags returns the Runtime flag subset stored in its Flags
 // instance.
 func (f *Flags) RuntimeFlags() RuntimeFlags {
 	if p := f.groups[Runtime]; p == nil {
 		return RuntimeFlags{}
 	}
 	from := f.groups[Runtime].(*RuntimeFlags)
 	to := *from
 	to.NamespaceRoots = make([]string, len(from.NamespaceRoots))
 	copy(to.NamespaceRoots, from.NamespaceRoots)
 	return to
 }

 // ListenFlags returns a copy of the Listen flag group stored in Flags.
 // This copy will contain default values if the Listen flag group
 // was not specified when CreateAndRegister was called. The HasGroup
 // method can be used for testing to see if any given group was configured.
 func (f *Flags) ListenFlags() ListenFlags {
 	if p := f.groups[Listen]; p != nil {
 		lf := p.(*ListenFlags)
 		n := *lf
 		if len(lf.Addrs) == 0 {
 			n.Addrs = ListenAddrs{{n.protocol.String(),
 				n.addresses.validator.String()}}
 			return n
 		}
 		n.Addrs = make(ListenAddrs, len(lf.Addrs))
 		copy(n.Addrs, lf.Addrs)
 		return n
 	}
 	return ListenFlags{}
 }

 // ACLFlags returns a copy of the ACL flag group stored in Flags.
 // This copy will contain default values if the ACL flag group
 // was not specified when CreateAndRegister was called. The HasGroup
 // method can be used for testing to see if any given group was configured.
 func (f *Flags) ACLFlags() ACLFlags {
 	if p := f.groups[ACL]; p != nil {
 		return *(p.(*ACLFlags))
 	}
 	return ACLFlags{}
 }

 // HasGroup returns group if the supplied FlagGroup has been created
 // for these Flags.
 func (f *Flags) HasGroup(group FlagGroup) bool {
 	_, present := f.groups[group]
 	return present
 }

 // Args returns the unparsed args, as per flag.Args.
 func (f *Flags) Args() []string {
 	return f.FlagSet.Args()
 }

 // readEnv reads the legacy NAMESPACE_ROOT?, VEYRON_CREDENTIALS,
 // and VANADIUM_I18N_CATALOGUE env vars.
 func readEnv() ([]string, string, string) {
 	roots := []string{}
 	for _, ev := range os.Environ() {
 		p := strings.SplitN(ev, "=", 2)
 		if len(p) != 2 {
 			continue
 		}
 		k, v := p[0], p[1]
 		if strings.HasPrefix(k, consts.NamespaceRootPrefix) && len(v) > 0 {
 			roots = append(roots, v)
 		}
 	}
 	return roots, os.Getenv(consts.VeyronCredentials), os.Getenv(consts.I18nCatalogueFiles)
 }

 // Parse parses the supplied args, as per flag.Parse.  The config can optionally
 // specify flag overrides.
 func (f *Flags) Parse(args []string, cfg map[string]string) error {
 	// TODO(cnicolaou): implement a single env var 'VANADIUM_OPTS'
 	// that can be used to specify any command line.
 	fs := f.FlagSet
 	if fs == flag.CommandLine {
 		// We treat the default command-line flag set specially w.r.t.
 		// printing out the build binary metadata: we want to display it
 		// as the first thing in the help message for the binary.
 		//
 		// We do this by overriding the usage function for the duration
 		// of the Parse.
 		oldUsage := fs.Usage
 		defer func() {
 			fs.Usage = oldUsage
 		}()
 		fs.Usage = func() {
 			fmt.Fprintf(os.Stderr, "Binary info: %s\n", buildinfo.Info())
 			if oldUsage == nil {
 				flag.Usage()
 			} else {
 				oldUsage()
 			}
 		}
 	}

 	if err := f.FlagSet.Parse(args); err != nil {
 		return err
 	}
 	for k, v := range cfg {
 		if f.FlagSet.Lookup(k) != nil {
 			f.FlagSet.Set(k, v)
 		}
 	}

 	hasrt := f.groups[Runtime] != nil
 	if hasrt {
 		runtime := f.groups[Runtime].(*RuntimeFlags)
 		if runtime.namespaceRootsFlag.isSet {
 			// command line overrides the environment.
 			runtime.NamespaceRoots = runtime.namespaceRootsFlag.roots
 		} else {
 			// we have a default value for the command line, which
 			// is only used if the environment variables have not been
 			// supplied.
 			if len(runtime.NamespaceRoots) == 0 {
 				runtime.NamespaceRoots = runtime.namespaceRootsFlag.roots
 			}
 		}
 	}
 	return nil
 }
	package flags

	import (
	"flag"
	"fmt"
	"os"
	"strings"
	"sync"

	"v.io/x/ref/lib/flags/buildinfo"
	"v.io/x/ref/lib/flags/consts"
	)

	// FlagGroup is the type for identifying groups of related flags.
	type FlagGroup int

	const (
	// Runtime identifies the flags and associated environment variables
	// used by the Vanadium process runtime. Namely:
	// --veyron.namespace.root (which may be repeated to supply multiple values)
	// --veyron.credentials
	// --veyron.vtrace.sample_rate
	// --veyron.vtrace.dump_on_shutdown
	// --veyron.vtrace.cache_size
	// --veyron.vtrace.collect_regexp
	Runtime FlagGroup = iota
	// Listen identifies the flags typically required to configure
	// ipc.ListenSpec. Namely:
	// --veyron.tcp.protocol
	// --veyron.tcp.address
	// --veyron.proxy
	// --vanadium.i18n_catalogue
	Listen
	// --veyron.acl.file (which may be repeated to supply multiple values)
	// ACL files are named - i.e. --veyron.acl=<name>:<file> with the
	// name <runtime> reserved for use by the runtime.
	// --veyron.acl.literal
	ACL
	)

	const defaultNamespaceRoot = "/ns.dev.v.io:8101"

	// Flags represents the set of flag groups created by a call to
	// CreateAndRegister.
	type Flags struct {
	FlagSet *flag.FlagSet
	groups map[FlagGroup]interface{}
	}

	type namespaceRootFlagVar struct {
	isSet bool // is true when a flag has been explicitly set.
	roots []string
	}

	func (nsr *namespaceRootFlagVar) String() string {
	return fmt.Sprintf("%v", nsr.roots)
	}

	func (nsr *namespaceRootFlagVar) Set(v string) error {
	if !nsr.isSet {
	// override the default value
	nsr.isSet = true
	nsr.roots = []string{}
	}
	for _, t := range nsr.roots {
	if v == t {
	return nil
	}
	}
	nsr.roots = append(nsr.roots, v)
	return nil
	}

	type aclFlagVar struct {
	isSet bool
	files map[string]string
	}

	func (aclf *aclFlagVar) String() string {
	return fmt.Sprintf("%v", aclf.files)
	}

	func (aclf *aclFlagVar) Set(v string) error {
	if !aclf.isSet {
	// override the default value
	aclf.isSet = true
	aclf.files = make(map[string]string)
	}
	parts := strings.SplitN(v, ":", 2)
	if len(parts) != 2 {
	return fmt.Errorf("%q is not in 'name:file' format", v)
	}
	name, file := parts[0], parts[1]
	aclf.files[name] = file
	return nil
	}

	// RuntimeFlags contains the values of the Runtime flag group.
	type RuntimeFlags struct {
	// NamespaceRoots may be initialized by NAMESPACE_ROOT* enivornment
	// variables as well as --veyron.namespace.root. The command line
	// will override the environment.
	NamespaceRoots []string // TODO(cnicolaou): provide flag.Value impl

	// Credentials may be initialized by the VEYRON_CREDENTIALS
	// environment variable. The command line will override the environment.
	Credentials string // TODO(cnicolaou): provide flag.Value impl

	// I18nCatalogue may be initialized by the VANADIUM_I18N_CATALOGUE
	// environment variable. The command line will override the
	// environment.
	I18nCatalogue string

	// Vtrace flags control various aspects of Vtrace.
	Vtrace VtraceFlags

	namespaceRootsFlag namespaceRootFlagVar
	}

	type VtraceFlags struct {
	// VtraceSampleRate is the rate (from 0.0 - 1.0) at which
	// vtrace traces started by this process are sampled for collection.
	SampleRate float64

	// VtraceDumpOnShutdown tells the runtime to dump all stored traces
	// to Stderr at shutdown if true.
	DumpOnShutdown bool

	// VtraceCacheSize is the number of traces to cache in memory.
	// TODO(mattr): Traces can be of widely varying size, we should have
	// some better measurement then just number of traces.
	CacheSize int

	// SpanRegexp matches a regular expression against span names and
	// annotations and forces any trace matching trace to be collected.
	CollectRegexp string
	}

	// ACLFlags contains the values of the ACLFlags flag group.
	type ACLFlags struct {
	// List of named ACL files.
	fileFlag aclFlagVar

	// Single json string, overrides everything.
	literal string
	}

	// ACLFile returns the file which is presumed to contain ACL information
	// associated with the supplied name parameter.
	func (af ACLFlags) ACLFile(name string) string {
	return af.fileFlag.files[name]
	}

	func (af ACLFlags) ACLLiteral() string {
	return af.literal
	}

	// ListenAddrs is the set of listen addresses captured from the command line.
	// ListenAddrs mirrors ipc.ListenAddrs.
	type ListenAddrs []struct {
	Protocol, Address string
	}

	// ListenFlags contains the values of the Listen flag group.
	type ListenFlags struct {
	Addrs ListenAddrs
	ListenProxy string
	protocol TCPProtocolFlag
	addresses ipHostPortFlagVar
	}

	type ipHostPortFlagVar struct {
	validator IPHostPortFlag
	flags *ListenFlags
	}

	// Implements flag.Value.Get
	func (ip ipHostPortFlagVar) Get() interface{} {
	return ip.String()
	}

	// Implements flag.Value.Set
	func (ip *ipHostPortFlagVar) Set(s string) error {
	if err := ip.validator.Set(s); err != nil {
	return err
	}
	a := struct {
	Protocol, Address string
	}{
	ip.flags.protocol.String(),
	ip.validator.String(),
	}
	for _, t := range ip.flags.Addrs {
	if t.Protocol == a.Protocol && t.Address == a.Address {
	return nil
	}
	}
	ip.flags.Addrs = append(ip.flags.Addrs, a)
	return nil
	}

	// Implements flag.Value.String
	func (ip ipHostPortFlagVar) String() string {
	s := ""
	for _, a := range ip.flags.Addrs {
	s += fmt.Sprintf("(%s %s)", a.Protocol, a.Address)
	}
	return s
	}

	// createAndRegisterRuntimeFlags creates and registers the RuntimeFlags
	// group with the supplied flag.FlagSet.
	func createAndRegisterRuntimeFlags(fs flag.FlagSet) RuntimeFlags {
	f := &RuntimeFlags{}
	roots, creds, i18nCatalogue := readEnv()
	if len(roots) == 0 {
	f.namespaceRootsFlag.roots = []string{defaultNamespaceRoot}
	} else {
	f.namespaceRootsFlag.roots = roots
	}

	fs.Var(&f.namespaceRootsFlag, "veyron.namespace.root", "local namespace root; can be repeated to provided multiple roots")
	fs.StringVar(&f.Credentials, "veyron.credentials", creds, "directory to use for storing security credentials")
	fs.StringVar(&f.I18nCatalogue, "vanadium.i18n_catalogue", i18nCatalogue, "18n catalogue files to load, comma separated")

	fs.Float64Var(&f.Vtrace.SampleRate, "veyron.vtrace.sample_rate", 0.0, "Rate (from 0.0 to 1.0) to sample vtrace traces.")
	fs.BoolVar(&f.Vtrace.DumpOnShutdown, "veyron.vtrace.dump_on_shutdown", true, "If true, dump all stored traces on runtime shutdown.")
	fs.IntVar(&f.Vtrace.CacheSize, "veyron.vtrace.cache_size", 1024, "The number of vtrace traces to store in memory.")
	fs.StringVar(&f.Vtrace.CollectRegexp, "veyron.vtrace.collect_regexp", "", "Spans and annotations that match this regular expression will trigger trace collection.")

	return f
	}

	func createAndRegisterACLFlags(fs flag.FlagSet) ACLFlags {
	f := &ACLFlags{}
	fs.Var(&f.fileFlag, "veyron.acl.file", "specify an acl file as <name>:<aclfile>")
	fs.StringVar(&f.literal, "veyron.acl.literal", "", "explicitly specify the runtime acl as a JSON-encoded access.TaggedACLMap. Overrides all --veyron.acl.file flags.")
	return f
	}

	var (
	defaultProtocol = "wsh" // GUARDED_BY listenMu
	defaultHostPort = ":0" // GUARDED_BY listenMu
	listenMu sync.RWMutex
	)

	// SetDefaultProtocol sets the default protocol used when --veyron.tcp.protocol is
	// not provided. It must be called before flags are parsed for it to take effect.
	func SetDefaultProtocol(protocol string) {
	listenMu.Lock()
	defaultProtocol = protocol
	listenMu.Unlock()
	}

	// SetDefaultHostPort sets the default host and port used when --veyron.tcp.address
	// is not provided. It must be called before flags are parsed for it to take effect.
	func SetDefaultHostPort(s string) {
	listenMu.Lock()
	defaultHostPort = s
	listenMu.Unlock()
	}

	// createAndRegisterListenFlags creates and registers the ListenFlags
	// group with the supplied flag.FlagSet.
	func createAndRegisterListenFlags(fs flag.FlagSet) ListenFlags {
	listenMu.RLock()
	defer listenMu.RUnlock()
	var ipHostPortFlag IPHostPortFlag
	if err := ipHostPortFlag.Set(defaultHostPort); err != nil {
	panic(err)
	}
	f := &ListenFlags{
	protocol: TCPProtocolFlag{defaultProtocol},
	addresses: ipHostPortFlagVar{validator: ipHostPortFlag},
	}
	f.addresses.flags = f

	fs.Var(&f.protocol, "veyron.tcp.protocol", "protocol to listen with")
	fs.Var(&f.addresses, "veyron.tcp.address", "address to listen on")
	fs.StringVar(&f.ListenProxy, "veyron.proxy", "", "object name of proxy service to use to export services across network boundaries")
	return f
	}

	// CreateAndRegister creates a new set of flag groups as specified by the
	// supplied flag group parameters and registers them with the supplied
	// flag.FlagSet.
	func CreateAndRegister(fs flag.FlagSet, groups ...FlagGroup) Flags {
	if len(groups) == 0 {
	return nil
	}
	f := &Flags{FlagSet: fs, groups: make(map[FlagGroup]interface{})}
	for _, g := range groups {
	switch g {
	case Runtime:
	f.groups[Runtime] = createAndRegisterRuntimeFlags(fs)
	case Listen:
	f.groups[Listen] = createAndRegisterListenFlags(fs)
	case ACL:
	f.groups[ACL] = createAndRegisterACLFlags(fs)
	}
	}
	return f
	}

	// RuntimeFlags returns the Runtime flag subset stored in its Flags
	// instance.
	func (f *Flags) RuntimeFlags() RuntimeFlags {
	if p := f.groups[Runtime]; p == nil {
	return RuntimeFlags{}
	}
	from := f.groups[Runtime].(*RuntimeFlags)
	to := *from
	to.NamespaceRoots = make([]string, len(from.NamespaceRoots))
	copy(to.NamespaceRoots, from.NamespaceRoots)
	return to
	}

	// ListenFlags returns a copy of the Listen flag group stored in Flags.
	// This copy will contain default values if the Listen flag group
	// was not specified when CreateAndRegister was called. The HasGroup
	// method can be used for testing to see if any given group was configured.
	func (f *Flags) ListenFlags() ListenFlags {
	if p := f.groups[Listen]; p != nil {
	lf := p.(*ListenFlags)
	n := *lf
	if len(lf.Addrs) == 0 {
	n.Addrs = ListenAddrs{{n.protocol.String(),
	n.addresses.validator.String()}}
	return n
	}
	n.Addrs = make(ListenAddrs, len(lf.Addrs))
	copy(n.Addrs, lf.Addrs)
	return n
	}
	return ListenFlags{}
	}

	// ACLFlags returns a copy of the ACL flag group stored in Flags.
	// This copy will contain default values if the ACL flag group
	// was not specified when CreateAndRegister was called. The HasGroup
	// method can be used for testing to see if any given group was configured.
	func (f *Flags) ACLFlags() ACLFlags {
	if p := f.groups[ACL]; p != nil {
	return (p.(ACLFlags))
	}
	return ACLFlags{}
	}

	// HasGroup returns group if the supplied FlagGroup has been created
	// for these Flags.
	func (f *Flags) HasGroup(group FlagGroup) bool {
	_, present := f.groups[group]
	return present
	}

	// Args returns the unparsed args, as per flag.Args.
	func (f *Flags) Args() []string {
	return f.FlagSet.Args()
	}

	// readEnv reads the legacy NAMESPACE_ROOT?, VEYRON_CREDENTIALS,
	// and VANADIUM_I18N_CATALOGUE env vars.
	func readEnv() ([]string, string, string) {
	roots := []string{}
	for _, ev := range os.Environ() {
	p := strings.SplitN(ev, "=", 2)
	if len(p) != 2 {
	continue
	}
	k, v := p[0], p[1]
	if strings.HasPrefix(k, consts.NamespaceRootPrefix) && len(v) > 0 {
	roots = append(roots, v)
	}
	}
	return roots, os.Getenv(consts.VeyronCredentials), os.Getenv(consts.I18nCatalogueFiles)
	}

	// Parse parses the supplied args, as per flag.Parse. The config can optionally
	// specify flag overrides.
	func (f *Flags) Parse(args []string, cfg map[string]string) error {
	// TODO(cnicolaou): implement a single env var 'VANADIUM_OPTS'
	// that can be used to specify any command line.
	fs := f.FlagSet
	if fs == flag.CommandLine {
	// We treat the default command-line flag set specially w.r.t.
	// printing out the build binary metadata: we want to display it
	// as the first thing in the help message for the binary.
	//
	// We do this by overriding the usage function for the duration
	// of the Parse.
	oldUsage := fs.Usage
	defer func() {
	fs.Usage = oldUsage
	}()
	fs.Usage = func() {
	fmt.Fprintf(os.Stderr, "Binary info: %s\n", buildinfo.Info())
	if oldUsage == nil {
	flag.Usage()
	} else {
	oldUsage()
	}
	}
	}

	if err := f.FlagSet.Parse(args); err != nil {
	return err
	}
	for k, v := range cfg {
	if f.FlagSet.Lookup(k) != nil {
	f.FlagSet.Set(k, v)
	}
	}

	hasrt := f.groups[Runtime] != nil
	if hasrt {
	runtime := f.groups[Runtime].(*RuntimeFlags)
	if runtime.namespaceRootsFlag.isSet {
	// command line overrides the environment.
	runtime.NamespaceRoots = runtime.namespaceRootsFlag.roots
	} else {
	// we have a default value for the command line, which
	// is only used if the environment variables have not been
	// supplied.
	if len(runtime.NamespaceRoots) == 0 {
	runtime.NamespaceRoots = runtime.namespaceRootsFlag.roots
	}
	}
	}
	return nil
	}