file watching only watches parent directory

Watching files only works in situations where standard files are in
use. In k8s, configmaps are mounted via a set of symlinks. In those
situations, you will only get file events when watching the directory
containing the symlink.

Fixes open-policy-agent#2588

Signed-off-by: Drew Wells <drew.wells00@gmail.com>

loader/loader.go

@@ -11,6 +11,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"sort"
 	"strings"
 
 	"github.com/ghodss/yaml"
@@ -302,6 +303,25 @@ func Paths(path string, recurse bool) (paths []string, err error) {
 	return paths, err
 }
 
+// Dirs resolves filepaths to directories. It will return a list of unique
+// directories.
+func Dirs(paths []string) []string {
+	unique := map[string]struct{}{}
+
+	for _, path := range paths {
+		// TODO: /dir/dir will register top level directory /dir
+		dir := filepath.Dir(path)
+		unique[dir] = struct{}{}
+	}
+
+	var u []string
+	for k := range unique {
+		u = append(u, k)
+	}
+	sort.Strings(u)
+	return u
+}
+
 // SplitPrefix returns a tuple specifying the document prefix and the file
 // path.
 func SplitPrefix(path string) ([]string, string) {

loader/loader_test.go

@@ -717,3 +717,15 @@ func mustListPaths(path string, recurse bool) (paths []string) {
 	}
 	return paths
 }
+
+func TestDirs(t *testing.T) {
+	paths := []string{
+		"/foo/bar.json", "/foo/bar/baz.json", "/foo.json",
+	}
+
+	e := []string{"/", "/foo", "/foo/bar"}
+	sorted := Dirs(paths)
+	if !reflect.DeepEqual(sorted, e) {
+		t.Errorf("got: %q wanted: %q", sorted, e)
+	}
+}

runtime/runtime.go

@@ -528,9 +528,13 @@ func (rt *Runtime) readWatcher(ctx context.Context, watcher *fsnotify.Watcher, p
 	for {
 		select {
 		case evt := <-watcher.Events:
+
 			removalMask := (fsnotify.Remove | fsnotify.Rename)
 			mask := (fsnotify.Create | fsnotify.Write | removalMask)
 			if (evt.Op & mask) != 0 {
+				logrus.WithFields(logrus.Fields{
+					"event": evt.String(),
+				}).Debugf("registered file event")
 				t0 := time.Now()
 				removed := ""
 				if (evt.Op & removalMask) != 0 {
@@ -656,6 +660,7 @@ func getWatcher(rootPaths []string) (*fsnotify.Watcher, error) {
 	}
 
 	for _, path := range watchPaths {
+		logrus.WithField("path", path).Debug("watching path")
 		if err := watcher.Add(path); err != nil {
 			return nil, err
 		}
@@ -675,7 +680,7 @@ func getWatchPaths(rootPaths []string) ([]string, error) {
 			return nil, err
 		}
 
-		paths = append(paths, result...)
+		paths = append(paths, loader.Dirs(result)...)
 	}
 
 	return paths, nil

runtime/runtime_test.go

@@ -13,6 +13,7 @@ import (
 	"net/http/httptest"
 	"os"
 	"path"
+	"path/filepath"
 	"reflect"
 	"strings"
 	"testing"
@@ -36,7 +37,7 @@ func TestWatchPaths(t *testing.T) {
 	}
 
 	expected := []string{
-		"/foo", "/foo/bar", "/foo/bar/baz.json",
+		".", "/foo", "/foo/bar",
 	}
 
 	test.WithTempFS(fs, func(rootDir string) {
@@ -46,10 +47,10 @@ func TestWatchPaths(t *testing.T) {
 		}
 		result := []string{}
 		for _, path := range paths {
-			result = append(result, strings.TrimPrefix(path, rootDir))
+			result = append(result, filepath.Clean(strings.TrimPrefix(path, rootDir)))
 		}
 		if !reflect.DeepEqual(expected, result) {
-			t.Fatalf("Expected %v but got: %v", expected, result)
+			t.Fatalf("Expected %q but got: %q", expected, result)
 		}
 	})
 }