Add flag to 'tunnel create' subcommand to specify a base64-encoded secret

cmd/cloudflared/tunnel/cmd.go

@@ -181,7 +181,8 @@ func Init(ver string, gracefulShutdown chan struct{}) {
 func runAdhocNamedTunnel(sc *subcommandContext, name, credentialsOutputPath string) error {
 	tunnel, ok, err := sc.tunnelActive(name)
 	if err != nil || !ok {
-		tunnel, err = sc.create(name, credentialsOutputPath)
+		// pass empty string as secret to generate one
+		tunnel, err = sc.create(name, credentialsOutputPath, "")
 		if err != nil {
 			return errors.Wrap(err, "failed to create tunnel")
 		}

cmd/cloudflared/tunnel/subcommand_context.go

@@ -1,6 +1,7 @@
 package tunnel
 
 import (
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"os"
@@ -148,15 +149,27 @@ func (sc *subcommandContext) readTunnelCredentials(credFinder CredFinder) (conne
 	return credentials, nil
 }
 
-func (sc *subcommandContext) create(name string, credentialsFilePath string) (*tunnelstore.Tunnel, error) {
+func (sc *subcommandContext) create(name string, credentialsFilePath string, secret string) (*tunnelstore.Tunnel, error) {
 	client, err := sc.client()
 	if err != nil {
 		return nil, errors.Wrap(err, "couldn't create client to talk to Cloudflare Tunnel backend")
 	}
 
-	tunnelSecret, err := generateTunnelSecret()
-	if err != nil {
-		return nil, errors.Wrap(err, "couldn't generate the secret for your new tunnel")
+	var tunnelSecret []byte
+	if secret == "" {
+		tunnelSecret, err = generateTunnelSecret()
+		if err != nil {
+			return nil, errors.Wrap(err, "couldn't generate the secret for your new tunnel")
+		}
+	} else {
+		decodedSecret, err := base64.StdEncoding.DecodeString(secret)
+		if err != nil {
+			return nil, errors.Wrap(err, "Couldn't decode tunnel secret from base64")
+		}
+		tunnelSecret = []byte(decodedSecret)
+		if len(tunnelSecret) < 32 {
+			return nil, errors.New("Decoded tunnel secret must be at least 32 bytes long")
+		}
 	}
 
 	tunnel, err := client.CreateTunnel(name, tunnelSecret)

cmd/cloudflared/tunnel/subcommands.go

@@ -156,6 +156,12 @@ var (
 		Usage:   `Overwrites existing DNS records with this hostname`,
 		EnvVars: []string{"TUNNEL_FORCE_PROVISIONING_DNS"},
 	}
+	createSecretFlag = &cli.StringFlag{
+		Name:    "secret",
+		Aliases: []string{"s"},
+		Usage:   "Base64 encoded secret to set for the tunnel. The decoded secret must be at least 32 bytes long. If not specified, a random 32-byte secret will be generated.",
+		EnvVars: []string{"TUNNEL_CREATE_SECRET"},
+	}
 )
 
 func buildCreateCommand() *cli.Command {
@@ -170,7 +176,7 @@ func buildCreateCommand() *cli.Command {
   For example, to create a tunnel named 'my-tunnel' run:
 
   $ cloudflared tunnel create my-tunnel`,
-		Flags:              []cli.Flag{outputFormatFlag, credentialsFileFlagCLIOnly},
+		Flags:              []cli.Flag{outputFormatFlag, credentialsFileFlagCLIOnly, createSecretFlag},
 		CustomHelpTemplate: commandHelpTemplate(),
 	}
 }
@@ -196,7 +202,7 @@ func createCommand(c *cli.Context) error {
 	warningChecker := updater.StartWarningCheck(c)
 	defer warningChecker.LogWarningIfAny(sc.log)
 
-	_, err = sc.create(name, c.String(CredFileFlag))
+	_, err = sc.create(name, c.String(CredFileFlag), c.String(createSecretFlag.Name))
 	return errors.Wrap(err, "failed to create tunnel")
 }