Fix NGF fails to recover if conf files are unexpectedly removed (#1132)

Problem: When the http.conf file did not exist, any updates to NGF would cause NGF to error as it could not "replace" that file as it didn't exist.

Solution: Added a check to see if the error returned from trying to remove a conf file was a IsNotExist, if so, continue and act as if the file has been deleted.

internal/mode/static/nginx/file/manager.go

@@ -88,10 +88,18 @@ func NewManagerImpl(logger logr.Logger, osFileManager OSFileManager) *ManagerImp
 func (m *ManagerImpl) ReplaceFiles(files []File) error {
 	for _, path := range m.lastWrittenPaths {
 		if err := m.osFileManager.Remove(path); err != nil {
+			if os.IsNotExist(err) {
+				m.logger.Info(
+					"File not found when attempting to delete",
+					"path", path,
+					"error", err,
+				)
+				continue
+			}
 			return fmt.Errorf("failed to delete file %q: %w", path, err)
 		}
 
-		m.logger.Info("deleted file", "path", path)
+		m.logger.Info("Deleted file", "path", path)
 	}
 
 	// In some cases, NGINX reads files in runtime, like a JWK. If you remove such file, NGINX will fail
@@ -106,7 +114,7 @@ func (m *ManagerImpl) ReplaceFiles(files []File) error {
 		}
 
 		m.lastWrittenPaths = append(m.lastWrittenPaths, file.Path)
-		m.logger.Info("wrote file", "path", file.Path)
+		m.logger.Info("Wrote file", "path", file.Path)
 	}
 
 	return nil

internal/mode/static/nginx/file/manager_test.go

@@ -116,6 +116,26 @@ var _ = Describe("EventHandler", func() {
 		})
 	})
 
+	When("file does not exist", func() {
+		It("should not error", func() {
+			fakeOSMgr := &filefakes.FakeOSFileManager{}
+			mgr := file.NewManagerImpl(zap.New(), fakeOSMgr)
+
+			files := []file.File{
+				{
+					Type:    file.TypeRegular,
+					Path:    "regular-1.conf",
+					Content: []byte("regular-1"),
+				},
+			}
+
+			Expect(mgr.ReplaceFiles(files)).ToNot(HaveOccurred())
+
+			fakeOSMgr.RemoveReturns(os.ErrNotExist)
+			Expect(mgr.ReplaceFiles(files)).ToNot(HaveOccurred())
+		})
+	})
+
 	When("file type is not supported", func() {
 		It("should panic", func() {
 			mgr := file.NewManagerImpl(zap.New(), nil)