provisioners/local-exec: output the output

builtin/provisioners/local-exec/resource_provisioner.go

@@ -2,12 +2,14 @@ package localexec
 
 import (
 	"fmt"
+	"io"
 	"os/exec"
 	"runtime"
 
 	"github.com/armon/circbuf"
 	"github.com/hashicorp/terraform/helper/config"
 	"github.com/hashicorp/terraform/terraform"
+	"github.com/mitchellh/go-linereader"
 )
 
 const (
@@ -44,17 +46,35 @@ func (p *ResourceProvisioner) Apply(
 		flag = "-c"
 	}
 
+	// Setup the reader that will read the lines from the command
+	pr, pw := io.Pipe()
+	copyDoneCh := make(chan struct{})
+	go p.copyOutput(o, pr, copyDoneCh)
+
 	// Setup the command
 	cmd := exec.Command(shell, flag, command)
 	output, _ := circbuf.NewBuffer(maxBufSize)
-	cmd.Stderr = output
+	cmd.Stderr = io.MultiWriter(output, pw)
-	cmd.Stdout = output
+	cmd.Stdout = io.MultiWriter(output, pw)
+
+	// Output what we're about to run
+	o.Output(fmt.Sprintf(
+		"Executing: %s %s \"%s\"",
+		shell, flag, command))
 
 	// Run the command to completion
-	if err := cmd.Run(); err != nil {
+	err := cmd.Run()
+
+	// Close the write-end of the pipe so that the goroutine mirroring output
+	// ends properly.
+	pw.Close()
+	<-copyDoneCh
+
+	if err != nil {
 		return fmt.Errorf("Error running command '%s': %v. Output: %s",
 			command, err, output.Bytes())
 	}
+
 	return nil
 }
 
@@ -64,3 +84,12 @@ func (p *ResourceProvisioner) Validate(c *terraform.ResourceConfig) ([]string, [
 	}
 	return validator.Validate(c)
 }
+
+func (p *ResourceProvisioner) copyOutput(
+	o terraform.UIOutput, r io.Reader, doneCh chan<- struct{}) {
+	defer close(doneCh)
+	lr := linereader.New(r)
+	for line := range lr.Ch {
+		o.Output(line)
+	}
+}