proxy: pick up a random port and bind to the correct port

This PR changes the address to bind locally. Instead of binding to an
hardcoded port, we now let the OS pick up a random port for us. In order
to make this work, we had to introduce a new method to the `sql-proxy`
repo (planetscale/sql-proxy#52).

Both `pscale shell` and `pscale connect` now automatically binds to a
random port.

closes planetscale/surfaces#111

go.mod

@@ -17,7 +17,7 @@ require (
 	github.com/pkg/browser v0.0.0-20201112035734-206646e67786
 	github.com/pkg/errors v0.9.1
 	github.com/planetscale/planetscale-go v0.9.0
-	github.com/planetscale/sql-proxy v0.1.3
+	github.com/planetscale/sql-proxy v0.1.4
 	github.com/spf13/cobra v1.1.3
 	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.7.1

go.sum

@@ -251,6 +251,8 @@ github.com/planetscale/planetscale-go v0.9.0 h1:EY2BQNyBAWx8rjk5ecqcmulKyT8zheWa
 github.com/planetscale/planetscale-go v0.9.0/go.mod h1:R+07GStW2oGSfeTwWoplnimSEFzxIzEofOHgPFxArg0=
 github.com/planetscale/sql-proxy v0.1.3 h1:u0HA78rkasas2JOHEyA21LAtIx+HVU6W7yPeS1XJRow=
 github.com/planetscale/sql-proxy v0.1.3/go.mod h1:Z1F1p5YmoBV0mkbfApaFA0zYv0Ngxm4GT4VnvtCgoro=
+github.com/planetscale/sql-proxy v0.1.4 h1:RBTxrEXiF08W8GHTuHQ1Hn9aM79ibLSFZ3yX/dwsF/c=
+github.com/planetscale/sql-proxy v0.1.4/go.mod h1:lTxdxxilj2oOgVsZ5c1Eyjo/3XTEv0GZ8E2A33y6We8=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/posener/complete v1.1.1/go.mod h1:em0nMJCgc9GFtwrmVmEMR/ZL6WyhyjMBndrE9hABlRI=

internal/cmd/connect/connect.go

@@ -63,9 +63,15 @@ argument:
 				}
 			}
 
+			const localProxyAddr = "127.0.0.1"
+			localAddr := localProxyAddr + ":0"
+			if flags.localAddr != "" {
+				localAddr = flags.localAddr
+			}
+
 			proxyOpts := proxy.Options{
 				CertSource: proxyutil.NewRemoteCertSource(client),
-				LocalAddr:  flags.localAddr,
+				LocalAddr:  localAddr,
 				RemoteAddr: flags.remoteAddr,
 				Instance:   fmt.Sprintf("%s/%s/%s", cfg.Organization, database, branch),
 			}
@@ -74,16 +80,27 @@ argument:
 				proxyOpts.Logger = zap.NewNop()
 			}
 
-			fmt.Printf("Secure connection to databases %s and branch %s is established!.\n\nLocal address to connect your application: %s (press ctrl-c to quit)",
-				cmdutil.BoldBlue(database),
-				cmdutil.BoldBlue(branch),
-				cmdutil.BoldBlue(flags.localAddr))
-
 			p, err := proxy.NewClient(proxyOpts)
 			if err != nil {
 				return fmt.Errorf("couldn't create proxy client: %s", err)
 			}
 
+			go func() {
+				// this is blocking and will only return once p.Run() below is
+				// invoked
+				addr, err := p.LocalAddr()
+				if err != nil {
+					fmt.Printf("failed getting local addr: %s\n", err)
+					return
+				}
+
+				fmt.Printf("Secure connection to databases %s and branch %s is established!.\n\nLocal address to connect your application: %s (press ctrl-c to quit)",
+					cmdutil.BoldBlue(database),
+					cmdutil.BoldBlue(branch),
+					cmdutil.BoldBlue(addr.String()),
+				)
+			}()
+
 			// TODO(fatih): replace with signal.NotifyContext once Go 1.16 is released
 			// https://go-review.googlesource.com/c/go/+/219640
 			ctx = sigutil.WithSignal(ctx, syscall.SIGINT, syscall.SIGTERM)
@@ -92,7 +109,7 @@ argument:
 	}
 
 	cmd.PersistentFlags().StringVar(&cfg.Organization, "org", cfg.Organization, "The organization for the current user")
-	cmd.PersistentFlags().StringVar(&flags.localAddr, "local-addr", "127.0.0.1:3307",
+	cmd.PersistentFlags().StringVar(&flags.localAddr, "local-addr", "",
 		"Local address to bind and listen for connections")
 	cmd.PersistentFlags().StringVar(&flags.remoteAddr, "remote-addr", "",
 		"PlanetScale Database remote network address. By default the remote address is populated automatically from the PlanetScale API.")

internal/cmd/shell/shell.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"log"
+	"net"
 	"os"
 	"os/exec"
 	"syscall"
@@ -21,11 +22,6 @@ import (
 	"go.uber.org/zap"
 )
 
-const (
-	localProxyPort = "3307"
-	localProxyAddr = "127.0.0.1"
-)
-
 func ShellCmd(cfg *config.Config) *cobra.Command {
 	var flags struct {
 		localAddr  string
@@ -79,9 +75,15 @@ second argument:
 				}
 			}
 
+			const localProxyAddr = "127.0.0.1"
+			localAddr := localProxyAddr + ":0"
+			if flags.localAddr != "" {
+				localAddr = flags.localAddr
+			}
+
 			proxyOpts := proxy.Options{
 				CertSource: proxyutil.NewRemoteCertSource(client),
-				LocalAddr:  flags.localAddr,
+				LocalAddr:  localAddr,
 				RemoteAddr: flags.remoteAddr,
 				Instance:   fmt.Sprintf("%s/%s/%s", cfg.Organization, database, branch),
 			}
@@ -123,10 +125,20 @@ second argument:
 				return err
 			}
 
+			addr, err := p.LocalAddr()
+			if err != nil {
+				return err
+			}
+
+			host, port, err := net.SplitHostPort(addr.String())
+			if err != nil {
+				return err
+			}
+
 			mysqlArgs := []string{
 				fmt.Sprintf("--defaults-extra-file=%s", tmpFile),
-				"-h", localProxyAddr,
-				"-P", localProxyPort,
+				"-h", host,
+				"-P", port,
 			}
 
 			m := &mysql{}
@@ -138,7 +150,7 @@ second argument:
 
 	cmd.PersistentFlags().StringVar(&cfg.Organization, "org", cfg.Organization, "The organization for the current user")
 	cmd.PersistentFlags().StringVar(&flags.localAddr, "local-addr",
-		localProxyAddr+":"+localProxyPort, "Local address to bind and listen for connections")
+		"", "Local address to bind and listen for connections. By default the proxy binds to 127.0.0.1 with a random port.")
 	cmd.PersistentFlags().StringVar(&flags.remoteAddr, "remote-addr", "",
 		"PlanetScale Database remote network address. By default the remote address is populated automatically from the PlanetScale API.")
 	cmd.PersistentFlags().BoolVar(&flags.debug, "debug", false, "enable debug mode")

vendor/modules.txt

@@ -75,7 +75,7 @@ github.com/pkg/errors
 # github.com/planetscale/planetscale-go v0.9.0
 ## explicit
 github.com/planetscale/planetscale-go/planetscale
-# github.com/planetscale/sql-proxy v0.1.3
+# github.com/planetscale/sql-proxy v0.1.4
 ## explicit
 github.com/planetscale/sql-proxy/proxy
 github.com/planetscale/sql-proxy/sigutil