log: Simplify Debug et al to accept single argument only

The functions `Debug()`, `Info()` and related accept multiple arguments.
The first hunch would be that the logger would format those arguments
via a call to `fmt.Sprintf()`, and that's seemingly also the assumption
that many of our callsites had. But in fact, the logrus logger will call
`fmt.Sprint()`, which joins the arguments by spaces when neither of the
arguments is a string.

While not being obvious, the current definition also conflicts with the
`slog` package. While the respective functions there also accept a
variable number of arguments, they will instead be interpreted as key
value pairs of structured data.

Let's simplify our calling conventions such that the functions only
accept a single message parameter and adjust callsites that misused
these functions accordingly. This fixes a source of misformatted log
messages and prepares us for the conversion to the `slog` package.

7 files changed, 31 insertions, 11 deletions

diff --git a/internal/cache/walker.go b/internal/cache/walker.go
index aed509046..17d668f71 100644
--- a/internal/cache/walker.go
+++ b/internal/cache/walker.go
@@ -117,7 +117,7 @@ func (c *DiskCache) walkLoop(walkPath string) {
 		}
 
 		if err := c.cleanWalk(walkPath); err != nil {
-			logger.Error(err)
+			logger.WithError(err).Error("disk cache cleanup failed")
 		}
 
 		select {
diff --git a/internal/git/localrepo/refs.go b/internal/git/localrepo/refs.go
index fe38e93c3..984f916b7 100644
--- a/internal/git/localrepo/refs.go
+++ b/internal/git/localrepo/refs.go
@@ -164,7 +164,7 @@ func (repo *Repo) setDefaultBranchWithTransaction(ctx context.Context, txManager
 	}
 	defer func() {
 		if err := lockingFileWriter.Close(); err != nil {
-			log.FromContext(ctx).WithError(err).Error("closing locked HEAD: %w", err)
+			log.FromContext(ctx).WithError(err).Error("closing locked HEAD failed")
 		}
 	}()
 
diff --git a/internal/gitaly/repoutil/lock.go b/internal/gitaly/repoutil/lock.go
index 3bbf30716..f0c13d29a 100644
--- a/internal/gitaly/repoutil/lock.go
+++ b/internal/gitaly/repoutil/lock.go
@@ -41,7 +41,7 @@ func Lock(ctx context.Context, locator storage.Locator, repository storage.Repos
 
 	unlock := func() {
 		if err := locker.Close(); err != nil {
-			log.FromContext(ctx).Error("closing repository locker: %w", err)
+			log.FromContext(ctx).WithError(err).Error("closing repository locker failed")
 		}
 	}
 
diff --git a/internal/gitaly/service/repository/rename.go b/internal/gitaly/service/repository/rename.go
index 296d59e5c..29c35085e 100644
--- a/internal/gitaly/service/repository/rename.go
+++ b/internal/gitaly/service/repository/rename.go
@@ -62,7 +62,7 @@ func (s *server) renameRepository(ctx context.Context, sourceRepo, targetRepo *g
 	}
 	defer func() {
 		if err := sourceLocker.Close(); err != nil {
-			log.FromContext(ctx).Error("closing source repo locker: %w", err)
+			log.FromContext(ctx).WithError(err).Error("closing source repo locker failed")
 		}
 	}()
 
@@ -72,7 +72,7 @@ func (s *server) renameRepository(ctx context.Context, sourceRepo, targetRepo *g
 	}
 	defer func() {
 		if err := targetLocker.Close(); err != nil {
-			log.FromContext(ctx).Error("closing target repo locker: %w", err)
+			log.FromContext(ctx).WithError(err).Error("closing target repo locker failed")
 		}
 	}()
 
diff --git a/internal/grpc/backchannel/backchannel.go b/internal/grpc/backchannel/backchannel.go
index bcbc09c0e..d992ecb84 100644
--- a/internal/grpc/backchannel/backchannel.go
+++ b/internal/grpc/backchannel/backchannel.go
@@ -42,7 +42,7 @@ type yamuxLogWrapper struct {
 }
 
 func (l yamuxLogWrapper) Print(args ...any) {
-	l.logger.Info(args...)
+	l.logger.Info(fmt.Sprint(args...))
 }
 
 func (l yamuxLogWrapper) Printf(format string, args ...any) {
diff --git a/internal/grpc/middleware/cache/cache.go b/internal/grpc/middleware/cache/cache.go
index b9d5474ba..39dab9596 100644
--- a/internal/grpc/middleware/cache/cache.go
+++ b/internal/grpc/middleware/cache/cache.go
@@ -16,7 +16,7 @@ import (
 func methodErrLogger(logger log.Logger, method string) func(error) {
 	return func(err error) {
 		countMethodErr(method)
-		logger.WithField("full_method_name", method).Error(err)
+		logger.WithField("full_method_name", method).Error(err.Error())
 	}
 }
 
diff --git a/internal/log/logger.go b/internal/log/logger.go
index 9f07ec205..ebed6293e 100644
--- a/internal/log/logger.go
+++ b/internal/log/logger.go
@@ -23,10 +23,10 @@ type Logger interface {
 	Warnf(format string, args ...any)
 	Errorf(format string, args ...any)
 
-	Debug(args ...any)
-	Info(args ...any)
-	Warn(args ...any)
-	Error(args ...any)
+	Debug(msg string)
+	Info(msg string)
+	Warn(msg string)
+	Error(msg string)
 
 	StreamServerInterceptor(...grpcmwlogrus.Option) grpc.StreamServerInterceptor
 	UnaryServerInterceptor(...grpcmwlogrus.Option) grpc.UnaryServerInterceptor
@@ -57,6 +57,26 @@ func (l LogrusLogger) WithError(err error) Logger {
 	return LogrusLogger{Entry: l.Entry.WithError(err)}
 }
 
+// Debug writes a log message at debug level.
+func (l LogrusLogger) Debug(msg string) {
+	l.Entry.Debug(msg)
+}
+
+// Info writes a log message at info level.
+func (l LogrusLogger) Info(msg string) {
+	l.Entry.Info(msg)
+}
+
+// Warn writes a log message at warn level.
+func (l LogrusLogger) Warn(msg string) {
+	l.Entry.Warn(msg)
+}
+
+// Error writes a log message at error level.
+func (l LogrusLogger) Error(msg string) {
+	l.Entry.Error(msg)
+}
+
 // ToContext injects the logger into the given context so that it can be retrieved via `FromContext()`.
 func (l LogrusLogger) ToContext(ctx context.Context) context.Context {
 	return ctxlogrus.ToContext(ctx, l.Entry)