fix: log stderr in debug logs only

internal/config/command_executor.go

@@ -2,6 +2,7 @@ package config
 
 import (
 	"io"
+	"os"
 	"runtime"
 
 	"github.com/evilmartians/lefthook/internal/system"
@@ -25,7 +26,7 @@ func (c *commandExecutor) execute(commandLine string) bool {
 		args = []string{"sh", "-c", commandLine}
 	}
 
-	err := c.cmd.Run(args, "", system.NullReader, io.Discard)
+	err := c.cmd.Run(args, "", system.NullReader, io.Discard, os.Stderr)
 
 	return err == nil
 }

internal/config/skip_checker_test.go

@@ -10,7 +10,7 @@ import (
 
 type mockCmd struct{}
 
-func (mc mockCmd) Run(cmd []string, _root string, _in io.Reader, _out io.Writer) error {
+func (mc mockCmd) Run(cmd []string, _root string, _in io.Reader, _out io.Writer, _errOut io.Writer) error {
 	if len(cmd) == 3 && cmd[2] == "success" {
 		return nil
 	} else {

internal/git/command_executor.go

@@ -72,12 +72,17 @@ func (c CommandExecutor) CmdLinesWithinFolder(cmd []string, folder string) ([]st
 
 func (c CommandExecutor) execute(cmd []string, root string) (string, error) {
 	out := new(bytes.Buffer)
-	err := c.cmd.Run(cmd, root, system.NullReader, out)
-	strOut := out.String()
-
-	log.Debug("[lefthook] out: ", strOut)
+	errOut := new(bytes.Buffer)
+	err := c.cmd.Run(cmd, root, system.NullReader, out, errOut)
+	outString := out.String()
+
+	log.Debug("[lefthook] stdout: ", outString)
+	errString := errOut.String()
+	if len(errString) > 0 {
+		log.Debug("[lefthook] stderr: ", errString)
+	}
 
-	return strOut, err
+	return outString, err
 }
 
 func batchByLength(s []string, length int) [][]string {

internal/git/repository_test.go

@@ -12,7 +12,7 @@ type gitCmd struct {
 	cases map[string]string
 }
 
-func (g gitCmd) Run(cmd []string, _root string, _in io.Reader, out io.Writer) error {
+func (g gitCmd) Run(cmd []string, _root string, _in io.Reader, out io.Writer, _errOut io.Writer) error {
 	res, ok := g.cases[(strings.Join(cmd, " "))]
 	if !ok {
 		return errors.New("doesn't exist")

internal/lefthook/run_test.go

@@ -14,7 +14,7 @@ import (
 
 type gitCmd struct{}
 
-func (g gitCmd) Run([]string, string, io.Reader, io.Writer) error {
+func (g gitCmd) Run([]string, string, io.Reader, io.Writer, io.Writer) error {
 	return nil
 }
 

internal/lefthook/runner/runner.go

@@ -141,51 +141,63 @@ func (r *Runner) runLFSHook(ctx context.Context) error {
 		return err
 	}
 
-	if git.IsLFSAvailable() {
-		log.Debugf(
-			"[git-lfs] executing hook: git lfs %s %s", r.HookName, strings.Join(r.GitArgs, " "),
-		)
-		out := new(bytes.Buffer)
-		err := r.cmd.RunWithContext(
-			ctx,
-			append(
-				[]string{"git", "lfs", r.HookName},
-				r.GitArgs...,
-			),
-			"",
-			r.stdin,
-			out,
-		)
-
-		output := strings.Trim(out.String(), "\n")
-		if output != "" {
-			log.Debug("[git-lfs] out: ", output)
-		}
-		if err != nil {
-			log.Debug("[git-lfs] err: ", err)
+	if !git.IsLFSAvailable() {
+		if requiredExists || configExists {
+			log.Errorf(
+				"This Repository requires Git LFS, but 'git-lfs' wasn't found.\n"+
+					"Install 'git-lfs' or consider reviewing the files:\n"+
+					"  - %s\n"+
+					"  - %s\n",
+				lfsRequiredFile, lfsConfigFile,
+			)
+			return errors.New("git-lfs is required")
 		}
 
-		if err == nil && output != "" {
-			log.Info(output)
-		}
+		return nil
+	}
 
-		if err != nil && (requiredExists || configExists) {
-			log.Warnf("git-lfs command failed: %s\n", output)
-			return err
-		}
+	log.Debugf(
+		"[git-lfs] executing hook: git lfs %s %s", r.HookName, strings.Join(r.GitArgs, " "),
+	)
+	out := new(bytes.Buffer)
+	errOut := new(bytes.Buffer)
+	err = r.cmd.RunWithContext(
+		ctx,
+		append(
+			[]string{"git", "lfs", r.HookName},
+			r.GitArgs...,
+		),
+		"",
+		r.stdin,
+		out,
+		errOut,
+	)
+
+	outString := strings.Trim(out.String(), "\n")
+	if outString != "" {
+		log.Debug("[git-lfs] stdout: ", outString)
+	}
+	errString := strings.Trim(errOut.String(), "\n")
+	if errString != "" {
+		log.Debug("[git-lfs] stderr: ", errString)
+	}
+	if err != nil {
+		log.Debug("[git-lfs] error:  ", err)
+	}
 
-		return nil
+	if err == nil && outString != "" {
+		log.Info("[git-lfs] stdout: ", outString)
 	}
 
-	if requiredExists || configExists {
-		log.Errorf(
-			"This Repository requires Git LFS, but 'git-lfs' wasn't found.\n"+
-				"Install 'git-lfs' or consider reviewing the files:\n"+
-				"  - %s\n"+
-				"  - %s\n",
-			lfsRequiredFile, lfsConfigFile,
-		)
-		return errors.New("git-lfs is required")
+	if err != nil && (requiredExists || configExists) {
+		log.Warn("git-lfs command failed")
+		if len(outString) > 0 {
+			log.Warn("[git-lfs] stdout: ", outString)
+		}
+		if len(errString) > 0 {
+			log.Warn("[git-lfs] stderr: ", errString)
+		}
+		return err
 	}
 
 	return nil

internal/lefthook/runner/runner_test.go

@@ -38,11 +38,11 @@ func (e executor) Execute(_ctx context.Context, opts exec.Options, _in io.Reader
 	return
 }
 
-func (e cmd) RunWithContext(context.Context, []string, string, io.Reader, io.Writer) error {
+func (e cmd) RunWithContext(context.Context, []string, string, io.Reader, io.Writer, io.Writer) error {
 	return nil
 }
 
-func (g *gitCmd) Run(cmd []string, _root string, _in io.Reader, out io.Writer) error {
+func (g *gitCmd) Run(cmd []string, _root string, _in io.Reader, out io.Writer, _errOut io.Writer) error {
 	g.mux.Lock()
 	g.commands = append(g.commands, strings.Join(cmd, " "))
 	g.mux.Unlock()

internal/system/system.go

@@ -15,44 +15,53 @@ type osCmd struct{}
 var Cmd = osCmd{}
 
 type Command interface {
-	Run([]string, string, io.Reader, io.Writer) error
+	Run([]string, string, io.Reader, io.Writer, io.Writer) error
 }
 
 type CommandWithContext interface {
-	RunWithContext(context.Context, []string, string, io.Reader, io.Writer) error
+	RunWithContext(context.Context, []string, string, io.Reader, io.Writer, io.Writer) error
 }
 
 // Run runs system command with LEFTHOOK=0 in order to prevent calling
 // subsequent lefthook hooks.
-func (c osCmd) RunWithContext(ctx context.Context, command []string, root string, in io.Reader, out io.Writer) error {
-	log.Debug("[lefthook] cmd: ", command)
+func (c osCmd) RunWithContext(
+	ctx context.Context,
+	command []string,
+	root string,
+	in io.Reader,
+	out io.Writer,
+	errOut io.Writer,
+) error {
+	log.Debug("[lefthook] cmd:    ", command)
 
 	cmd := exec.CommandContext(ctx, command[0], command[1:]...)
 
-	return run(cmd, root, in, out)
+	return run(cmd, root, in, out, errOut)
 }
 
-func (c osCmd) Run(command []string, root string, in io.Reader, out io.Writer) error {
-	log.Debug("[lefthook] cmd: ", command)
+func (c osCmd) Run(command []string, root string, in io.Reader, out io.Writer, errOut io.Writer) error {
+	log.Debug("[lefthook] cmd:    ", command)
 
 	cmd := exec.Command(command[0], command[1:]...)
 
-	return run(cmd, root, in, out)
+	return run(cmd, root, in, out, errOut)
 }
 
-func run(cmd *exec.Cmd, root string, in io.Reader, out io.Writer) error {
+func run(cmd *exec.Cmd, root string, in io.Reader, out io.Writer, errOut io.Writer) error {
 	cmd.Env = append(os.Environ(), "LEFTHOOK=0")
 	if len(root) > 0 {
 		cmd.Dir = root
-		log.Debug("[lefthook] dir: ", root)
+		log.Debug("[lefthook] dir:    ", root)
 	}
 
 	cmd.Stdin = in
 	cmd.Stdout = out
-	cmd.Stderr = os.Stderr
+	cmd.Stderr = errOut
 
 	err := cmd.Run()
-	log.Debug("[lefthook] err: ", err)
+	if err != nil {
+		log.Debug("[lefthook] error:  ", err)
+	}
 
 	return err
 }