open-nomad/command/meta.go

58 lines
1.5 KiB
Go

package command
import (
"bufio"
"flag"
"io"
"github.com/mitchellh/cli"
)
// FlagSetFlags is an enum to define what flags are present in the
// default FlagSet returned by Meta.FlagSet.
type FlagSetFlags uint
const (
FlagSetNone FlagSetFlags = 0
FlagSetServer FlagSetFlags = 1 << iota
FlagSetDefault = FlagSetServer
)
// Meta contains the meta-options and functionality that nearly every
// Nomad command inherits.
type Meta struct {
Ui cli.Ui
// These are set by the command line flags.
flagAddress string
}
// FlagSet returns a FlagSet with the common flags that every
// command implements. The exact behavior of FlagSet can be configured
// using the flags as the second parameter, for example to disable
// server settings on the commands that don't talk to a server.
func (m *Meta) FlagSet(n string, fs FlagSetFlags) *flag.FlagSet {
f := flag.NewFlagSet(n, flag.ContinueOnError)
// FlagSetServer tells us to enable the settings for selecting
// the server information.
if fs&FlagSetServer != 0 {
f.StringVar(&m.flagAddress, "address", "", "")
}
// Create an io.Writer that writes to our Ui properly for errors.
// This is kind of a hack, but it does the job. Basically: create
// a pipe, use a scanner to break it into lines, and output each line
// to the UI. Do this forever.
errR, errW := io.Pipe()
errScanner := bufio.NewScanner(errR)
go func() {
for errScanner.Scan() {
m.Ui.Error(errScanner.Text())
}
}()
f.SetOutput(errW)
return f
}