Add explicit sync to disk for critical file writes (#1686)

For Orbit operations, make an explicit *os.File.Sync() call and check the 
error, to make sure the writes are fully flushed to disk.

Closes #1679 .

changes/issue-1679-sync-file-writes

@@ -0,0 +1 @@
+* Orbit: sync critical file writes to disk.

cmd/fleetctl/config.go

@@ -60,7 +60,10 @@ func makeConfigIfNotExists(fp string) error {
 		}
 	}
 
-	_, err := secure.OpenFile(fp, os.O_RDONLY|os.O_CREATE, configFilePerms)
+	f, err := secure.OpenFile(fp, os.O_RDONLY|os.O_CREATE, configFilePerms)
+	if err == nil {
+		f.Close()
+	}
 	return err
 }
 

orbit/pkg/packaging/linux_shared.go

@@ -137,6 +137,9 @@ func buildNFPM(opt Options, pkger nfpm.Packager) error {
 	if err := pkger.Package(info, out); err != nil {
 		return errors.Wrap(err, "write package")
 	}
+	if err := out.Sync(); err != nil {
+		return errors.Wrap(err, "sync output file")
+	}
 	log.Info().Str("path", filename).Msg("wrote package")
 
 	return nil

orbit/pkg/packaging/macos.go

@@ -316,9 +316,9 @@ func cpio(srcPath, dstPath string) error {
 	if err != nil {
 		return errors.Wrap(err, "wait gzip")
 	}
-	err = dst.Close()
+	err = dst.Sync()
 	if err != nil {
-		return errors.Wrap(err, "close dst")
+		return errors.Wrap(err, "sync dst")
 	}
 
 	return nil

orbit/pkg/packaging/packaging.go

@@ -70,6 +70,9 @@ func copyFile(srcPath, dstPath string, perm os.FileMode) error {
 	if _, err := io.Copy(dst, src); err != nil {
 		return errors.Wrap(err, "copy src to dst")
 	}
+	if err := dst.Sync(); err != nil {
+		return errors.Wrap(err, "sync dst after copy")
+	}
 
 	return nil
 }

orbit/pkg/update/filestore/filestore.go

@@ -88,7 +88,10 @@ func (s *fileStore) writeData() error {
 	defer f.Close()
 
 	if err := json.NewEncoder(f).Encode(s.metadata); err != nil {
-		return errors.Wrap(err, "read file store")
+		return errors.Wrap(err, "write file store")
+	}
+	if err := f.Sync(); err != nil {
+		return errors.Wrap(err, "sync file store")
 	}
 
 	return nil