Add a build package (#1926)

* Add a build package

* fix go mod

* package tar

build/golang/golang.go

@@ -0,0 +1,75 @@
+// Package golang is a go package manager
+package golang
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/micro/go-micro/v3/build"
+)
+
+type goBuild struct {
+	Options build.Options
+	Cmd     string
+	Path    string
+}
+
+// whichGo locates the go command
+func whichGo() string {
+	// check GOROOT
+	if gr := os.Getenv("GOROOT"); len(gr) > 0 {
+		return filepath.Join(gr, "bin", "go")
+	}
+
+	// check path
+	for _, p := range filepath.SplitList(os.Getenv("PATH")) {
+		bin := filepath.Join(p, "go")
+		if _, err := os.Stat(bin); err == nil {
+			return bin
+		}
+	}
+
+	// best effort
+	return "go"
+}
+
+func (g *goBuild) Package(name string, src *build.Source) (*build.Package, error) {
+	binary := filepath.Join(g.Path, name)
+	source := src.Path
+
+	cmd := exec.Command(g.Cmd, "build", "-o", binary, source)
+	if err := cmd.Run(); err != nil {
+		return nil, err
+	}
+
+	return &build.Package{
+		Name:   name,
+		Path:   binary,
+		Type:   g.String(),
+		Source: src,
+	}, nil
+}
+
+func (g *goBuild) Remove(b *build.Package) error {
+	binary := filepath.Join(b.Path, b.Name)
+	return os.Remove(binary)
+}
+
+func (g *goBuild) String() string {
+	return "golang"
+}
+
+func NewBuild(opts ...build.Option) build.Build {
+	options := build.Options{
+		Path: os.TempDir(),
+	}
+	for _, o := range opts {
+		o(&options)
+	}
+	return &goBuild{
+		Options: options,
+		Cmd:     whichGo(),
+		Path:    options.Path,
+	}
+}