internal/task: use bootstrap Go to run releaselet

I have no idea how this ever worked. We know the ARM64 Windows machines
can't run ARM32 binaries, which is why we don't have 32-bit builders on
them. So how did building the releaselet with the ARM32 toolchain work
until now? What changed? The mysteries of life.

Change-Id: Ia8893047717ef9722727d0797fb351e0c314fb69
Reviewed-on: https://go-review.googlesource.com/c/build/+/531457
LUCI-TryBot-Result: Go LUCI <[email protected]>
Auto-Submit: Heschi Kreinick <[email protected]>
Reviewed-by: Robert Findley <[email protected]>

Author: heschi

internal/relui/buildrelease_test.go

@@ -68,6 +68,20 @@ func TestSecurity(t *testing.T) {
 const fakeGo = `#!/bin/bash -eu
 
 case "$1" in
+"run")
+  case "$2" in
+  "releaselet.go")
+    # We're building an MSI. The command should be run in the gomote work dir.
+    ls go/src/make.bash >/dev/null
+    mkdir msi
+    echo "I'm an MSI!" > msi/thisisanmsi.msi
+    ;;
+  *)
+    echo "unknown main file $2"
+    exit 1
+    ;;
+  esac
+  ;;
 "get")
   ls go.mod go.sum >/dev/null
   for i in "${@:2}"; do
@@ -507,12 +521,6 @@ mkdir -p $GO/bin
 cat <<'EOF' >$GO/bin/go
 #!/bin/bash -eu
 case "$@" in
-"run releaselet.go")
-    # We're building an MSI. The command should be run in the gomote work dir.
-	ls go/src/make.bash >/dev/null
-	mkdir msi
-	echo "I'm an MSI!" > msi/thisisanmsi.msi
-	;;
 "install -race")
 	# Installing the race mode stdlib. Doesn't matter where it's run.
 	mkdir -p $(dirname $0)/../pkg/something_orother/
@@ -598,7 +606,7 @@ var goFiles = map[string]string{
 
 func serveBootstrap(w http.ResponseWriter, r *http.Request) {
 	task.ServeTarball("go-builder-data/go", map[string]string{
-		"bin/go": "I'm a dummy bootstrap go command!",
+		"bin/go": fakeGo,
 	}, w, r)
 }
 

internal/task/buildrelease.go

@@ -447,14 +447,18 @@ func (b *BuildletStep) ConvertPKGToTGZ(ctx *workflow.TaskContext, in io.Reader,
 var releaselet string
 
 func (b *BuildletStep) BuildWindowsMSI(ctx *workflow.TaskContext, binaryArchive io.Reader, msi io.Writer) error {
+	ctx.Printf("Installing bootstrap go")
+	if err := b.Buildlet.PutTarFromURL(ctx, b.BuildConfig.GoBootstrapURL(buildenv.Production), "bootstrap_go"); err != nil {
+		return err
+	}
 	if err := b.Buildlet.PutTar(ctx, binaryArchive, ""); err != nil {
 		return err
 	}
 	ctx.Printf("Pushing and running releaselet.")
 	if err := b.Buildlet.Put(ctx, strings.NewReader(releaselet), "releaselet.go", 0666); err != nil {
 		return err
 	}
-	if err := b.runGo(ctx, []string{"run", "releaselet.go"}, buildlet.ExecOpts{
+	if err := b.exec(ctx, "bootstrap_go/bin/go", []string{"run", "releaselet.go"}, buildlet.ExecOpts{
 		Dir: ".", // root of buildlet work directory
 	}); err != nil {
 		ctx.Printf("releaselet failed: %v", err)