syncthing/vendor/gopkg.in/urfave/cli.v1/altsrc/flag.go
Jakob Borg 916ec63af6 cmd/stdiscosrv: New discovery server (fixes #4618)
This is a new revision of the discovery server. Relevant changes and
non-changes:

- Protocol towards clients is unchanged.

- Recommended large scale design is still to be deployed nehind nginx (I
  tested, and it's still a lot faster at terminating TLS).

- Database backend is leveldb again, only. It scales enough, is easy to
  setup, and we don't need any backend to take care of.

- Server supports replication. This is a simple TCP channel - protect it
  with a firewall when deploying over the internet. (We deploy this within
  the same datacenter, and with firewall.) Any incoming client announces
  are sent over the replication channel(s) to other peer discosrvs.
  Incoming replication changes are applied to the database as if they came
  from clients, but without the TLS/certificate overhead.

- Metrics are exposed using the prometheus library, when enabled.

- The database values and replication protocol is protobuf, because JSON
  was quite CPU intensive when I tried that and benchmarked it.

- The "Retry-After" value for failed lookups gets slowly increased from
  a default of 120 seconds, by 5 seconds for each failed lookup,
  independently by each discosrv. This lowers the query load over time for
  clients that are never seen. The Retry-After maxes out at 3600 after a
  couple of weeks of this increase. The number of failed lookups is
  stored in the database, now and then (avoiding making each lookup a
  database put).

All in all this means clients can be pointed towards a cluster using
just multiple A / AAAA records to gain both load sharing and redundancy
(if one is down, clients will talk to the remaining ones).

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4648
2018-01-14 08:52:31 +00:00

262 lines
7.3 KiB
Go

package altsrc
import (
"fmt"
"strconv"
"strings"
"syscall"
"gopkg.in/urfave/cli.v1"
)
// FlagInputSourceExtension is an extension interface of cli.Flag that
// allows a value to be set on the existing parsed flags.
type FlagInputSourceExtension interface {
cli.Flag
ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error
}
// ApplyInputSourceValues iterates over all provided flags and
// executes ApplyInputSourceValue on flags implementing the
// FlagInputSourceExtension interface to initialize these flags
// to an alternate input source.
func ApplyInputSourceValues(context *cli.Context, inputSourceContext InputSourceContext, flags []cli.Flag) error {
for _, f := range flags {
inputSourceExtendedFlag, isType := f.(FlagInputSourceExtension)
if isType {
err := inputSourceExtendedFlag.ApplyInputSourceValue(context, inputSourceContext)
if err != nil {
return err
}
}
}
return nil
}
// InitInputSource is used to to setup an InputSourceContext on a cli.Command Before method. It will create a new
// input source based on the func provided. If there is no error it will then apply the new input source to any flags
// that are supported by the input source
func InitInputSource(flags []cli.Flag, createInputSource func() (InputSourceContext, error)) cli.BeforeFunc {
return func(context *cli.Context) error {
inputSource, err := createInputSource()
if err != nil {
return fmt.Errorf("Unable to create input source: inner error: \n'%v'", err.Error())
}
return ApplyInputSourceValues(context, inputSource, flags)
}
}
// InitInputSourceWithContext is used to to setup an InputSourceContext on a cli.Command Before method. It will create a new
// input source based on the func provided with potentially using existing cli.Context values to initialize itself. If there is
// no error it will then apply the new input source to any flags that are supported by the input source
func InitInputSourceWithContext(flags []cli.Flag, createInputSource func(context *cli.Context) (InputSourceContext, error)) cli.BeforeFunc {
return func(context *cli.Context) error {
inputSource, err := createInputSource(context)
if err != nil {
return fmt.Errorf("Unable to create input source with context: inner error: \n'%v'", err.Error())
}
return ApplyInputSourceValues(context, inputSource, flags)
}
}
// ApplyInputSourceValue applies a generic value to the flagSet if required
func (f *GenericFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
if f.set != nil {
if !context.IsSet(f.Name) && !isEnvVarSet(f.EnvVar) {
value, err := isc.Generic(f.GenericFlag.Name)
if err != nil {
return err
}
if value != nil {
eachName(f.Name, func(name string) {
f.set.Set(f.Name, value.String())
})
}
}
}
return nil
}
// ApplyInputSourceValue applies a StringSlice value to the flagSet if required
func (f *StringSliceFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
if f.set != nil {
if !context.IsSet(f.Name) && !isEnvVarSet(f.EnvVar) {
value, err := isc.StringSlice(f.StringSliceFlag.Name)
if err != nil {
return err
}
if value != nil {
var sliceValue cli.StringSlice = value
eachName(f.Name, func(name string) {
underlyingFlag := f.set.Lookup(f.Name)
if underlyingFlag != nil {
underlyingFlag.Value = &sliceValue
}
})
}
}
}
return nil
}
// ApplyInputSourceValue applies a IntSlice value if required
func (f *IntSliceFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
if f.set != nil {
if !context.IsSet(f.Name) && !isEnvVarSet(f.EnvVar) {
value, err := isc.IntSlice(f.IntSliceFlag.Name)
if err != nil {
return err
}
if value != nil {
var sliceValue cli.IntSlice = value
eachName(f.Name, func(name string) {
underlyingFlag := f.set.Lookup(f.Name)
if underlyingFlag != nil {
underlyingFlag.Value = &sliceValue
}
})
}
}
}
return nil
}
// ApplyInputSourceValue applies a Bool value to the flagSet if required
func (f *BoolFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
if f.set != nil {
if !context.IsSet(f.Name) && !isEnvVarSet(f.EnvVar) {
value, err := isc.Bool(f.BoolFlag.Name)
if err != nil {
return err
}
if value {
eachName(f.Name, func(name string) {
f.set.Set(f.Name, strconv.FormatBool(value))
})
}
}
}
return nil
}
// ApplyInputSourceValue applies a BoolT value to the flagSet if required
func (f *BoolTFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
if f.set != nil {
if !context.IsSet(f.Name) && !isEnvVarSet(f.EnvVar) {
value, err := isc.BoolT(f.BoolTFlag.Name)
if err != nil {
return err
}
if !value {
eachName(f.Name, func(name string) {
f.set.Set(f.Name, strconv.FormatBool(value))
})
}
}
}
return nil
}
// ApplyInputSourceValue applies a String value to the flagSet if required
func (f *StringFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
if f.set != nil {
if !(context.IsSet(f.Name) || isEnvVarSet(f.EnvVar)) {
value, err := isc.String(f.StringFlag.Name)
if err != nil {
return err
}
if value != "" {
eachName(f.Name, func(name string) {
f.set.Set(f.Name, value)
})
}
}
}
return nil
}
// ApplyInputSourceValue applies a int value to the flagSet if required
func (f *IntFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
if f.set != nil {
if !(context.IsSet(f.Name) || isEnvVarSet(f.EnvVar)) {
value, err := isc.Int(f.IntFlag.Name)
if err != nil {
return err
}
if value > 0 {
eachName(f.Name, func(name string) {
f.set.Set(f.Name, strconv.FormatInt(int64(value), 10))
})
}
}
}
return nil
}
// ApplyInputSourceValue applies a Duration value to the flagSet if required
func (f *DurationFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
if f.set != nil {
if !(context.IsSet(f.Name) || isEnvVarSet(f.EnvVar)) {
value, err := isc.Duration(f.DurationFlag.Name)
if err != nil {
return err
}
if value > 0 {
eachName(f.Name, func(name string) {
f.set.Set(f.Name, value.String())
})
}
}
}
return nil
}
// ApplyInputSourceValue applies a Float64 value to the flagSet if required
func (f *Float64Flag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
if f.set != nil {
if !(context.IsSet(f.Name) || isEnvVarSet(f.EnvVar)) {
value, err := isc.Float64(f.Float64Flag.Name)
if err != nil {
return err
}
if value > 0 {
floatStr := float64ToString(value)
eachName(f.Name, func(name string) {
f.set.Set(f.Name, floatStr)
})
}
}
}
return nil
}
func isEnvVarSet(envVars string) bool {
for _, envVar := range strings.Split(envVars, ",") {
envVar = strings.TrimSpace(envVar)
if _, ok := syscall.Getenv(envVar); ok {
// TODO: Can't use this for bools as
// set means that it was true or false based on
// Bool flag type, should work for other types
return true
}
}
return false
}
func float64ToString(f float64) string {
return fmt.Sprintf("%v", f)
}
func eachName(longName string, fn func(string)) {
parts := strings.Split(longName, ",")
for _, name := range parts {
name = strings.Trim(name, " ")
fn(name)
}
}