github.com/ggriffiths/terraform@v0.9.0-beta1.0.20170222213024-79c4935604cb/command/ui_input.go (about)

     1  package command
     2  
     3  import (
     4  	"bufio"
     5  	"bytes"
     6  	"errors"
     7  	"fmt"
     8  	"io"
     9  	"log"
    10  	"os"
    11  	"os/signal"
    12  	"strings"
    13  	"sync"
    14  	"unicode"
    15  
    16  	"github.com/hashicorp/terraform/terraform"
    17  	"github.com/mitchellh/colorstring"
    18  )
    19  
    20  var defaultInputReader io.Reader
    21  var defaultInputWriter io.Writer
    22  var testInputResponse []string
    23  
    24  // UIInput is an implementation of terraform.UIInput that asks the CLI
    25  // for input stdin.
    26  type UIInput struct {
    27  	// Colorize will color the output.
    28  	Colorize *colorstring.Colorize
    29  
    30  	// Reader and Writer for IO. If these aren't set, they will default to
    31  	// Stdout and Stderr respectively.
    32  	Reader io.Reader
    33  	Writer io.Writer
    34  
    35  	interrupted bool
    36  	l           sync.Mutex
    37  	once        sync.Once
    38  }
    39  
    40  func (i *UIInput) Input(opts *terraform.InputOpts) (string, error) {
    41  	i.once.Do(i.init)
    42  
    43  	r := i.Reader
    44  	w := i.Writer
    45  	if r == nil {
    46  		r = defaultInputReader
    47  	}
    48  	if w == nil {
    49  		w = defaultInputWriter
    50  	}
    51  	if r == nil {
    52  		r = os.Stdin
    53  	}
    54  	if w == nil {
    55  		w = os.Stdout
    56  	}
    57  
    58  	// Make sure we only ask for input once at a time. Terraform
    59  	// should enforce this, but it doesn't hurt to verify.
    60  	i.l.Lock()
    61  	defer i.l.Unlock()
    62  
    63  	// If we're interrupted, then don't ask for input
    64  	if i.interrupted {
    65  		return "", errors.New("interrupted")
    66  	}
    67  
    68  	// If we have test results, return those
    69  	if testInputResponse != nil {
    70  		v := testInputResponse[0]
    71  		testInputResponse = testInputResponse[1:]
    72  		return v, nil
    73  	}
    74  
    75  	log.Printf("[DEBUG] command: asking for input: %q", opts.Query)
    76  
    77  	// Listen for interrupts so we can cancel the input ask
    78  	sigCh := make(chan os.Signal, 1)
    79  	signal.Notify(sigCh, os.Interrupt)
    80  	defer signal.Stop(sigCh)
    81  
    82  	// Build the output format for asking
    83  	var buf bytes.Buffer
    84  	buf.WriteString("[reset]")
    85  	buf.WriteString(fmt.Sprintf("[bold]%s[reset]\n", opts.Query))
    86  	if opts.Description != "" {
    87  		s := bufio.NewScanner(strings.NewReader(opts.Description))
    88  		for s.Scan() {
    89  			buf.WriteString(fmt.Sprintf("  %s\n", s.Text()))
    90  		}
    91  		buf.WriteString("\n")
    92  	}
    93  	if opts.Default != "" {
    94  		buf.WriteString("  [bold]Default:[reset] ")
    95  		buf.WriteString(opts.Default)
    96  		buf.WriteString("\n")
    97  	}
    98  	buf.WriteString("  [bold]Enter a value:[reset] ")
    99  
   100  	// Ask the user for their input
   101  	if _, err := fmt.Fprint(w, i.Colorize.Color(buf.String())); err != nil {
   102  		return "", err
   103  	}
   104  
   105  	// Listen for the input in a goroutine. This will allow us to
   106  	// interrupt this if we are interrupted (SIGINT)
   107  	result := make(chan string, 1)
   108  	go func() {
   109  		buf := bufio.NewReader(r)
   110  		line, err := buf.ReadString('\n')
   111  		if err != nil {
   112  			log.Printf("[ERR] UIInput scan err: %s", err)
   113  		}
   114  
   115  		result <- strings.TrimRightFunc(line, unicode.IsSpace)
   116  	}()
   117  
   118  	select {
   119  	case line := <-result:
   120  		fmt.Fprint(w, "\n")
   121  
   122  		if line == "" {
   123  			line = opts.Default
   124  		}
   125  
   126  		return line, nil
   127  	case <-sigCh:
   128  		// Print a newline so that any further output starts properly
   129  		// on a new line.
   130  		fmt.Fprintln(w)
   131  
   132  		// Mark that we were interrupted so future Ask calls fail.
   133  		i.interrupted = true
   134  
   135  		return "", errors.New("interrupted")
   136  	}
   137  }
   138  
   139  func (i *UIInput) init() {
   140  	if i.Colorize == nil {
   141  		i.Colorize = &colorstring.Colorize{
   142  			Colors:  colorstring.DefaultColors,
   143  			Disable: true,
   144  		}
   145  	}
   146  }