terraform/command/ui_input.go

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package command
import (
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"bufio"
"bytes"
"errors"
"fmt"
"io"
"log"
"os"
"os/signal"
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"strings"
"sync"
"github.com/hashicorp/terraform/terraform"
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"github.com/mitchellh/colorstring"
)
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var defaultInputReader io.Reader
var defaultInputWriter io.Writer
// UIInput is an implementation of terraform.UIInput that asks the CLI
// for input stdin.
type UIInput struct {
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// Colorize will color the output.
Colorize *colorstring.Colorize
// Reader and Writer for IO. If these aren't set, they will default to
// Stdout and Stderr respectively.
Reader io.Reader
Writer io.Writer
interrupted bool
l sync.Mutex
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once sync.Once
}
func (i *UIInput) Input(opts *terraform.InputOpts) (string, error) {
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i.once.Do(i.init)
r := i.Reader
w := i.Writer
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if r == nil {
r = defaultInputReader
}
if w == nil {
w = defaultInputWriter
}
if r == nil {
r = os.Stdin
}
if w == nil {
w = os.Stdout
}
// Make sure we only ask for input once at a time. Terraform
// should enforce this, but it doesn't hurt to verify.
i.l.Lock()
defer i.l.Unlock()
// If we're interrupted, then don't ask for input
if i.interrupted {
return "", errors.New("interrupted")
}
// Listen for interrupts so we can cancel the input ask
sigCh := make(chan os.Signal, 1)
signal.Notify(sigCh, os.Interrupt)
defer signal.Stop(sigCh)
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// Build the output format for asking
var buf bytes.Buffer
buf.WriteString("[reset]")
buf.WriteString(fmt.Sprintf("[bold]%s[reset]\n", opts.Query))
if opts.Description != "" {
s := bufio.NewScanner(strings.NewReader(opts.Description))
for s.Scan() {
buf.WriteString(fmt.Sprintf(" %s\n", s.Text()))
}
buf.WriteString("\n")
}
buf.WriteString(" [bold]Enter a value:[reset] ")
// Ask the user for their input
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if _, err := fmt.Fprint(w, i.Colorize.Color(buf.String())); err != nil {
return "", err
}
// Listen for the input in a goroutine. This will allow us to
// interrupt this if we are interrupted (SIGINT)
result := make(chan string, 1)
go func() {
var line string
if _, err := fmt.Fscanln(r, &line); err != nil {
log.Printf("[ERR] UIInput scan err: %s", err)
}
result <- line
}()
select {
case line := <-result:
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fmt.Fprint(w, "\n")
return line, nil
case <-sigCh:
// Print a newline so that any further output starts properly
// on a new line.
fmt.Fprintln(w)
// Mark that we were interrupted so future Ask calls fail.
i.interrupted = true
return "", errors.New("interrupted")
}
}
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func (i *UIInput) init() {
if i.Colorize == nil {
i.Colorize = &colorstring.Colorize{
Colors: colorstring.DefaultColors,
Disable: true,
}
}
}