feat: allow hiding pipeline values in validation output

- Add a `-q` / `--quiet` flag to support suppressing the pipeline values
  added in CircleCI-Public#855
- Print the config values one line at a time, and add newlines
- Write to stderr so that outputting to a file won't generate invalid
  YAML when writing files to stdout
Fixes CircleCI-Public#860

cmd/config.go

@@ -3,6 +3,7 @@ package cmd
 import (
 	"fmt"
 	"io/ioutil"
+	"os"
 	"strings"
 
 	"github.com/CircleCI-Public/circleci-cli/api"
@@ -28,6 +29,7 @@ type configOptions struct {
 // Used to for compatibility with `circleci config validate --path`
 var configPath string
 var ignoreDeprecatedImages bool // should we ignore deprecated images warning
+var quietOutput bool            // Suppress extra diagnostic output
 
 var configAnnotations = map[string]string{
 	"<path>": "The path to your config (use \"-\" for STDIN)",
@@ -73,6 +75,7 @@ func newConfigCommand(config *settings.Config) *cobra.Command {
 	}
 	validateCommand.Annotations["<path>"] = configAnnotations["<path>"]
 	validateCommand.PersistentFlags().StringVarP(&configPath, "config", "c", ".circleci/config.yml", "path to config file")
+	validateCommand.PersistentFlags().BoolVarP(&quietOutput, "quiet", "q", false, "Suppress verbose output")
 	validateCommand.PersistentFlags().BoolVar(&ignoreDeprecatedImages, "ignore-deprecated-images", false, "ignores the deprecated images error")
 	if err := validateCommand.PersistentFlags().MarkHidden("config"); err != nil {
 		panic(err)
@@ -139,8 +142,9 @@ func validateConfig(opts configOptions, flags *pflag.FlagSet) error {
 
 	//if no orgId provided use org slug
 	values := pipeline.LocalPipelineValues()
-	fmt.Println("Validating config with following values")
-	printValues(values)
+	if !(quietOutput) {
+		printValues(values)
+	}
 
 	orgID, _ := flags.GetString("org-id")
 	if strings.TrimSpace(orgID) != "" {
@@ -197,7 +201,6 @@ func processConfig(opts configOptions, flags *pflag.FlagSet) error {
 
 	//if no orgId provided use org slug
 	values := pipeline.LocalPipelineValues()
-	fmt.Println("Processing config with following values")
 	printValues(values)
 
 	orgID, _ := flags.GetString("org-id")
@@ -237,7 +240,8 @@ func migrateConfig(opts configOptions) error {
 }
 
 func printValues(values pipeline.Values) {
+	fmt.Fprintln(os.Stderr, "Processing config with following values:")
 	for key, value := range values {
-		fmt.Printf("\t%s:\t%s", key, value)
+		fmt.Fprintf(os.Stderr, "%-18s %s\n", key+":", value)
 	}
 }