Let users set the port for process-compose

Author: Lagoja

internal/boxcli/services.go

@@ -20,6 +20,7 @@ type serviceUpFlags struct {
 	background          bool
 	processComposeFile  string
 	processComposeFlags []string
+	pcport              int
 }
 
 type serviceStopFlags struct {
@@ -38,6 +39,8 @@ func (flags *serviceUpFlags) register(cmd *cobra.Command) {
 		&flags.background, "background", "b", false, "run service in background")
 	cmd.Flags().StringArrayVar(
 		&flags.processComposeFlags, "pcflags", []string{}, "pass flags directly to process compose")
+	cmd.Flags().IntVarP(
+		&flags.pcport, "pcport", "p", 0, "specify the port for process-compose to use. You can also set the pcport by exporting PC_PORT_NUM")
 }
 
 func (flags *serviceStopFlags) register(cmd *cobra.Command) {
@@ -245,6 +248,10 @@ func startProcessManager(
 		return err
 	}
 
+	if flags.pcport < 0 {
+		return errors.Errorf("invalid pcport %d: ports cannot be less than 0", flags.pcport)
+	}
+
 	box, err := devbox.Open(&devopt.Opts{
 		Dir:                      servicesFlags.config.path,
 		Env:                      env,
@@ -263,6 +270,7 @@ func startProcessManager(
 		devopt.ProcessComposeOpts{
 			Background: flags.background,
 			ExtraFlags: flags.processComposeFlags,
+			PCPort:     flags.pcport,
 		},
 	)
 }

internal/devbox/devopt/devboxopts.go

@@ -20,6 +20,7 @@ type Opts struct {
 type ProcessComposeOpts struct {
 	ExtraFlags []string
 	Background bool
+	PCPort     int
 }
 
 type GenerateOpts struct {

internal/devbox/services.go

@@ -3,6 +3,7 @@ package devbox
 import (
 	"context"
 	"fmt"
+	"strconv"
 	"text/tabwriter"
 
 	"go.jetpack.io/devbox/internal/boxcli/usererr"
@@ -217,6 +218,9 @@ func (d *Devbox) StartProcessManager(
 		for _, flag := range processComposeOpts.ExtraFlags {
 			args = append(args, "--pcflags", flag)
 		}
+		if processComposeOpts.PCPort != 0 {
+			args = append(args, "--pcport", strconv.Itoa(processComposeOpts.PCPort))
+		}
 
 		return d.runDevboxServicesScript(ctx, args)
 	}
@@ -257,6 +261,7 @@ func (d *Devbox) StartProcessManager(
 			BinPath:    processComposeBinPath,
 			Background: processComposeOpts.Background,
 			ExtraFlags: processComposeOpts.ExtraFlags,
+			PCPort:     processComposeOpts.PCPort,
 		},
 	)
 }

internal/services/manager.go

@@ -44,6 +44,7 @@ type ProcessComposeOpts struct {
 	BinPath    string
 	ExtraFlags []string
 	Background bool
+	PCPort     int
 }
 
 func newGlobalProcessComposeConfig() *globalProcessComposeConfig {
@@ -128,10 +129,13 @@ func StartProcessManager(
 	config := readGlobalProcessComposeJSON(configFile)
 	config.File = configFile
 
-	// Get the port to use for this project
-	port, err := getAvailablePort()
+	port, err := selectPort(processComposeConfig.PCPort)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to select port: %v", err)
+	}
+
+	if !isPortAvailable(port) {
+		return fmt.Errorf("port %d is already in use", port)
 	}
 
 	// Start building the process-compose command

internal/services/ports.go

@@ -1,7 +1,10 @@
 package services
 
 import (
+	"fmt"
 	"net"
+	"os"
+	"strconv"
 
 	"github.com/pkg/errors"
 )
@@ -60,6 +63,34 @@ func getAvailablePort() (int, error) {
 	return 0, errors.New("no available port")
 }
 
+func selectPort(configPort int) (int, error) {
+	if configPort != 0 {
+		return configPort, nil
+	}
+
+	if portStr, exists := os.LookupEnv("PC_PORT_NUM"); exists {
+		port, err := strconv.Atoi(portStr)
+		if err != nil {
+			return 0, fmt.Errorf("invalid PC_PORT_NUM environment variable: %v", err)
+		}
+		if port <= 0 {
+			return 0, fmt.Errorf("invalid PC_PORT_NUM environment variable: ports cannot be less than 0")
+		}
+		return port, nil
+	}
+
+	return getAvailablePort()
+}
+
 func isAllowed(port int) bool {
 	return port > 1024 && disallowedPorts[port] == ""
 }
+
+func isPortAvailable(port int) bool {
+	ln, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
+	if err != nil {
+		return false
+	}
+	ln.Close()
+	return true
+}