feat(parser): handle terragrunt as parser binary (#87)

terragrunt needs the --terragrunt-log-disable flag to produce clean JSON
output only

Author: norman-zon

parser/binary-parser.go

@@ -15,15 +15,19 @@ type BinaryParser struct {
 
 func (j BinaryParser) Parse() (tfjson.Plan, error) {
 	tfbinary := "terraform"
+	cmdArgs := []string{"show", "-json", j.fileName}
 	if tfoverride, ok := os.LookupEnv("TF_BINARY"); ok {
+		if tfoverride == "terragrunt" {
+			cmdArgs = append(cmdArgs, "--terragrunt-log-disable")
+		}
 		tfbinary = tfoverride
 	}
-	cmd := exec.Command(tfbinary, "show", "-json", j.fileName)
+	cmd := exec.Command(tfbinary, cmdArgs...)
 	output, err := cmd.CombinedOutput()
 	if err != nil {
 		return tfjson.Plan{}, fmt.Errorf(
-			"error when running 'terraform show -json %s': \n%s\n\n%s",
-			j.fileName, output, "Make sure you are running in terraform directory and terraform init is done")
+			"error when running '%s show -json %s': \n%s\n\nMake sure you are running in %s directory and %s init is done",
+			tfbinary, j.fileName, output, tfbinary, tfbinary)
 	}
 	plan := tfjson.Plan{}
 	err = json.Unmarshal(output, &plan)