Add check flag to fmt command (open-policy-agent#655)

* Add fail flag to fmt command Signed-off-by: John Reese <[email protected]> * Update command to be check Signed-off-by: John Reese <[email protected]>
seanpm2001 · Jan 4, 2022 · ab9c9f1 · ab9c9f1
1 parent 06793a4
commit ab9c9f1
Showing 1 changed file with 19 additions and 0 deletions.
diff --git a/internal/commands/fmt.go b/internal/commands/fmt.go
@@ -3,13 +3,15 @@ package commands
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
 
 	"github.com/open-policy-agent/opa/format"
 	"github.com/open-policy-agent/opa/loader"
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
 )
 
 // NewFormatCommand creates a format command.
@@ -18,6 +20,13 @@ func NewFormatCommand(ctx context.Context) *cobra.Command {
 	cmd := cobra.Command{
 		Use:   "fmt <path> [path [...]]",
 		Short: "Format Rego files",
+		PreRunE: func(cmd *cobra.Command, args []string) error {
+			if err := viper.BindPFlag("check", cmd.Flags().Lookup("check")); err != nil {
+				return fmt.Errorf("bind flag: %w", err)
+			}
+
+			return nil
+		},
 		RunE: func(cmd *cobra.Command, files []string) error {
 			policies, err := loader.AllRegos(files)
 			if err != nil {
@@ -42,10 +51,18 @@ func NewFormatCommand(ctx context.Context) *cobra.Command {
 					return fmt.Errorf("format: %w", err)
 				}
 
+				// If the original file contents match the formatted contents, formatting does not
+				// need to be done and we can try the next module.
 				if bytes.Equal(contents, formattedContents) {
 					continue
 				}
 
+				// When we are running the format command in check mode and the file contents are different
+				// we want to return an error code to the user and not update any of the files.
+				if viper.GetBool("check") {
+					return errors.New("files not formatted")
+				}
+
 				outfile, err := os.OpenFile(policy.Package.Location.File, os.O_WRONLY|os.O_TRUNC, info.Mode().Perm())
 				if err != nil {
 					return fmt.Errorf("open file for write: %w", err)
@@ -62,5 +79,7 @@ func NewFormatCommand(ctx context.Context) *cobra.Command {
 		},
 	}
 
+	cmd.Flags().Bool("check", false, "Returns a non-zero exit code if the policies are not formatted")
+
 	return &cmd
 }