refactor term interrupts & have RunContext take a conf struct now

command/build.go

@@ -6,12 +6,9 @@ import (
 	"fmt"
 	"log"
 	"math"
-	"os"
-	"os/signal"
 	"strconv"
 	"strings"
 	"sync"
-	"syscall"
 
 	"github.com/hashicorp/hcl/v2"
 	"github.com/hashicorp/hcl/v2/hclparse"
@@ -29,30 +26,15 @@ type BuildCommand struct {
 }
 
 func (c *BuildCommand) Run(args []string) int {
-	buildCtx, cancelBuildCtx := context.WithCancel(context.Background())
+	buildCtx, cleanup := handleTermInterrupt(c.Ui)
-	// Handle interrupts for this build
+	defer cleanup()
-	sigCh := make(chan os.Signal, 1)
-	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
-	defer func() {
-		cancelBuildCtx()
-		signal.Stop(sigCh)
-		close(sigCh)
-	}()
-	go func() {
-		select {
-		case sig := <-sigCh:
-			if sig == nil {
-				// context got cancelled and this closed chan probably
-				// triggered first
-				return
-			}
-			c.Ui.Error(fmt.Sprintf("Cancelling build after receiving %s", sig))
-			cancelBuildCtx()
-		case <-buildCtx.Done():
-		}
-	}()
 
-	return c.RunContext(buildCtx, args)
+	cfg, ret := c.ParseArgs(args)
+	if ret != 0 {
+		return ret
+	}
+
+	return c.RunContext(buildCtx, cfg)
 }
 
 // Config is the command-configuration parsed from the command line.
@@ -207,11 +189,7 @@ func (m *Meta) GetConfigFromJSON(path string) (BuildStarter, int) {
 	}, ret
 }
 
-func (c *BuildCommand) RunContext(buildCtx context.Context, args []string) int {
+func (c *BuildCommand) RunContext(buildCtx context.Context, cfg Config) int {
-	cfg, ret := c.ParseArgs(args)
-	if ret != 0 {
-		return ret
-	}
 
 	packerStarter, ret := c.GetConfig(cfg.Path)
 	if ret != 0 {

command/cli.go

@@ -71,7 +71,7 @@ func (ba *BuildArgs) AddFlagSets(flags *flag.FlagSet) {
 
 func (ba *BuildArgs) ParseArgvs(args []string) int {
 	flags := flag.NewFlagSet("build", flag.ContinueOnError)
-	flags.Usage = func() { ba.Ui.Say(ba.Help()) }
+	// flags.Usage = func() { ba.Ui.Say(ba.Help()) }
 	ba.AddFlagSets(flags)
 	err := flags.Parse(args)
 	if err != nil {
@@ -96,7 +96,7 @@ type BuildArgs struct {
 
 func (ca *ConsoleArgs) ParseArgvs(args []string) int {
 	flags := flag.NewFlagSet("console", flag.ContinueOnError)
-	flags.Usage = func() { ca.Ui.Say(ca.Help()) }
+	// flags.Usage = func() { ca.Ui.Say(ca.Help()) }
 	ca.AddFlagSets(flags)
 	err := flags.Parse(args)
 	if err != nil {
@@ -118,7 +118,7 @@ func (fa *FixArgs) AddFlagSets(flags *flag.FlagSet) {
 
 func (fa *FixArgs) ParseArgvs(args []string) int {
 	flags := flag.NewFlagSet("fix", flag.ContinueOnError)
-	flags.Usage = func() { fa.Ui.Say(fa.Help()) }
+	// flags.Usage = func() { fa.Ui.Say(fa.Help()) }
 	fa.AddFlagSets(flags)
 	err := flags.Parse(args)
 	if err != nil {
@@ -143,7 +143,7 @@ func (va *ValidateArgs) AddFlagSets(flags *flag.FlagSet) {
 
 func (va *ValidateArgs) ParseArgvs(args []string) int {
 	flags := flag.NewFlagSet("validate", flag.ContinueOnError)
-	flags.Usage = func() { va.Ui.Say(va.Help()) }
+	// flags.Usage = func() { va.Ui.Say(va.Help()) }
 	va.AddFlagSets(flags)
 	err := flags.Parse(args)
 	if err != nil {

command/signal.go

@@ -0,0 +1,37 @@
+package command
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/hashicorp/packer/packer"
+)
+
+func handleTermInterrupt(ui packer.Ui) (context.Context, func()) {
+	ctx, cancelCtx := context.WithCancel(context.Background())
+	// Handle interrupts for this build
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
+	cleanup := func() {
+		cancelCtx()
+		signal.Stop(sigCh)
+		close(sigCh)
+	}
+	go func() {
+		select {
+		case sig := <-sigCh:
+			if sig == nil {
+				// context got cancelled and this closed chan probably
+				// triggered first
+				return
+			}
+			ui.Error(fmt.Sprintf("Cancelling build after receiving %s", sig))
+			cancelCtx()
+		case <-ctx.Done():
+		}
+	}()
+	return ctx, cleanup
+}