gitservice: use an error hook instead of a logger (#56611)

src-cli doesn't use logger, so this changes the pattern to instead make
how we log injectable by the client. Currently the logger is just not
set in src-cli leading to a nil pointer panic. After this is merged a
follow up PR will go out for that.

Additionally this PR fixes a use for sourcegraph app which didn't set
the logger as well.

Test Plan: CI

cmd/gitserver/server/gitservice.go

@@ -74,12 +74,14 @@ func (s *Server) gitServiceHandler() *gitservice.Handler {
 	logger := s.Logger.Scoped("gitServiceHandler", "smart Git HTTP transfer protocol")
 
 	return &gitservice.Handler{
-		Logger: logger,
-
 		Dir: func(d string) string {
 			return string(repoDirFromName(s.ReposDir, api.RepoName(d)))
 		},
 
+		ErrorHook: func(err error, stderr string) {
+			logger.Error("git-service error", log.Error(err), log.String("stderr", stderr))
+		},
+
 		// Limit rate of stdout from git.
 		CommandHook: func(cmd *exec.Cmd) {
 			cmd.Stdout = flowrateWriter(logger, cmd.Stdout)

internal/service/servegit/serve.go

@@ -167,6 +167,9 @@ func (s *Serve) handler() http.Handler {
 			// calling FromSlash.
 			return filepath.FromSlash("/" + name)
 		},
+		ErrorHook: func(err error, stderr string) {
+			s.Logger.Error("git-service error", log.Error(err), log.String("stderr", stderr))
+		},
 		Trace: func(ctx context.Context, svc, repo, protocol string) func(error) {
 			start := time.Now()
 			return func(err error) {

lib/gitservice/BUILD.bazel

@@ -6,18 +6,12 @@ go_library(
     srcs = ["gitservice.go"],
     importpath = "github.com/sourcegraph/sourcegraph/lib/gitservice",
     visibility = ["//visibility:public"],
-    deps = [
-        "//lib/errors",
-        "@com_github_sourcegraph_log//:log",
-    ],
+    deps = ["//lib/errors"],
 )
 
 go_test(
     name = "gitservice_test",
     timeout = "short",
     srcs = ["gitservice_test.go"],
-    deps = [
-        ":gitservice",
-        "@com_github_sourcegraph_log//logtest",
-    ],
+    deps = [":gitservice"],
 )

lib/gitservice/gitservice.go

@@ -11,8 +11,6 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/sourcegraph/log"
-
 	"github.com/sourcegraph/sourcegraph/lib/errors"
 )
 
@@ -42,12 +40,17 @@ var uploadPackArgs = []string{
 // protocol. We aim to support modern git features such as protocol v2 to
 // minimize traffic.
 type Handler struct {
-	Logger log.Logger
-
 	// Dir is a funcion which takes a repository name and returns an absolute
 	// path to the GIT_DIR for it.
 	Dir func(string) string
 
+	// ErrorHook is called if we fail to run the git command. The main use of
+	// this is to inject logging. For example in src-cli we don't use
+	// sourcegraph/log so this allows us to use stdlib log.
+	//
+	// Note: This is required to be set
+	ErrorHook func(err error, stderr string)
+
 	// CommandHook if non-nil will run with the git upload command before we
 	// start the command.
 	//
@@ -148,7 +151,7 @@ func (s *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	err = cmd.Run()
 	if err != nil {
 		err = errors.Errorf("error running git service command args=%q: %w", args, err)
-		s.Logger.Error("git-service error", log.Error(err), log.String("stderr", stderr.String()))
+		s.ErrorHook(err, stderr.String())
 		_, _ = w.Write([]byte("\n" + err.Error() + "\n"))
 	}
 }

lib/gitservice/gitservice_test.go

@@ -9,7 +9,6 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/sourcegraph/log/logtest"
 	"github.com/sourcegraph/sourcegraph/lib/gitservice"
 )
 
@@ -34,7 +33,6 @@ func TestHandler(t *testing.T) {
 	}
 
 	ts := httptest.NewServer(&gitservice.Handler{
-		Logger: logtest.Scoped(t),
 		Dir: func(s string) string {
 			return filepath.Join(root, s, ".git")
 		},