generate rails secrets inline rather than shelling out (#3958)

generate rails secrets inline rather than shelling out

helpers/rand.go

@@ -3,6 +3,7 @@ package helpers
 
 import (
 	"crypto/rand"
+	"encoding/hex"
 	"math/big"
 	mrand "math/rand"
 	"time"
@@ -39,3 +40,13 @@ func RandBytes(n int) ([]byte, error) {
 
 	return token, nil
 }
+
+// RandHex generates a random hex string of a given length*2
+func RandHex(n int) (string, error) {
+	bytes, err := RandBytes(n)
+	if err != nil {
+		return "", err
+	}
+
+	return hex.EncodeToString(bytes), nil
+}

scanner/rails.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	"github.com/pkg/errors"
+	"github.com/superfly/flyctl/helpers"
 	"github.com/superfly/flyctl/internal/command/launch/plan"
 	"github.com/superfly/flyctl/internal/flyerr"
 	"gopkg.in/yaml.v2"
@@ -233,14 +234,14 @@ func configureRails(sourceDir string, config *ScannerConfig) (*SourceInfo, error
 		// support Rails 4 through 5.1 applications, ones that started out
 		// there and never were fully upgraded, and ones that intentionally
 		// avoid using Rails encrypted credentials.
-		out, err := exec.Command(binrails, "secret").Output()
+		out, err := helpers.RandHex(64)
 
 		if err == nil {
 			s.Secrets = []Secret{
 				{
 					Key:   "SECRET_KEY_BASE",
 					Help:  "Secret key used to verify the integrity of signed cookies",
-					Value: strings.TrimSpace(string(out)),
+					Value: out,
 				},
 			}
 		}