logp.Logger should expose a Close method to close any open files

[belimawr]

Currently the logp.Logger does not expose any API that allows for closing all open files, this causes problems on Windows making removing the directory with the open file to fail.

One simple way to reproduce it is to create a test that configures logp to log to a file in a folder returned by t.TempDir, when the test ends, there will be an error from testing.go that the folder could not be removed.

One option to work around this issue is to use os.MkdirTemp instead of t.TempDir.

Here is an example of a test that would fail on windows due to open files:

elastic-agent-libs/logp/core_test.go

Lines 230 to 245 in 25f61a1

	if runtime.GOOS == "windows" {
	var err error
	tempDir1, err = os.MkdirTemp("", t.Name()+"-*")
	if err != nil {
	t.Fatalf("could not create temporary directory: %s", err)
	}
	tempDir2, err = os.MkdirTemp("", t.Name()+"-*")
	if err != nil {
	t.Fatalf("could not create temporary directory: %s", err)
	}
	} else {
	// We have no problems on Linux and Darwin, so we can rely on t.TempDir
	// that will remove the files once the tests finishes.
	tempDir1 = t.TempDir()
	tempDir2 = t.TempDir()
	}

The file rotator we instantiate does expose a Close:

elastic-agent-libs/logp/core.go

Lines 242 to 252 in be95cca

	rotator, err := file.NewFileRotator(filename,
	file.MaxSizeBytes(cfg.Files.MaxSize),
	file.MaxBackups(cfg.Files.MaxBackups),
	file.Permissions(os.FileMode(cfg.Files.Permissions)),
	file.Interval(cfg.Files.Interval),
	file.RotateOnStartup(cfg.Files.RotateOnStartup),
	file.RedirectStderr(cfg.Files.RedirectStderr),
	)
	if err != nil {
	return nil, fmt.Errorf("failed to create file rotator: %w", err)
	}

elastic-agent-libs/file/rotator.go

Lines 371 to 375 in be95cca

	func (r *Rotator) Close() error {
	r.mutex.Lock()
	defer r.mutex.Unlock()
	return r.closeFile()
	}

however we do not keep a reference for it, completely losing access to it's Close method.