Add sutil CLI in cmd/sutil with internal/cli command tree

internal/cli/info.go

@@ -0,0 +1,54 @@
+package cli
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"runtime/debug"
+	"strings"
+
+	"github.com/spf13/cobra"
+)
+
+// ErrNoBuildInfo is returned by `sutil info` when the binary carries no
+// Go build information, which only happens for binaries not built with
+// module support.
+var ErrNoBuildInfo = errors.New("sutil: no build information in this binary")
+
+// newInfoCommand returns `sutil info`, which prints the build version, the
+// Go toolchain version, the module path, and the VCS metadata recorded by
+// the Go toolchain at build time.
+func newInfoCommand(p Params) *cobra.Command {
+	return &cobra.Command{
+		Use:   "info",
+		Short: "Print build information",
+		Args:  cobra.NoArgs,
+		RunE: func(cmd *cobra.Command, _ []string) error {
+			return writeBuildInfo(cmd.OutOrStdout(), p.Version)
+		},
+	}
+}
+
+// writeBuildInfo writes one "key: value" line per fact to w.
+func writeBuildInfo(w io.Writer, version string) error {
+	info, ok := debug.ReadBuildInfo()
+	if !ok {
+		return ErrNoBuildInfo
+	}
+
+	lines := []string{
+		"version: " + version,
+		"go: " + info.GoVersion,
+		"module: " + info.Main.Path,
+	}
+
+	for _, setting := range info.Settings {
+		if strings.HasPrefix(setting.Key, "vcs.") {
+			lines = append(lines, setting.Key+": "+setting.Value)
+		}
+	}
+
+	_, err := fmt.Fprintln(w, strings.Join(lines, "\n"))
+
+	return err
+}