overlay: honor ro option

if "ro" is specified when mounting overlay, configure overlay without any upper layer and workdir so the file system doesn't attempt to write any file. Closes: containers/buildah#2359 Signed-off-by: Giuseppe Scrivano <[email protected]>
giuseppe · May 16, 2020 · 95d90c1 · 95d90c1
1 parent c37a306
commit 95d90c1
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/drivers/overlay/overlay.go b/drivers/overlay/overlay.go
@@ -809,6 +809,13 @@ func (d *Driver) get(id string, disableShifting bool, options graphdriver.MountO
 	}
 	readWrite := true
 
+	for _, o := range options.Options {
+		if o == "ro" {
+			readWrite = false
+			break
+		}
+	}
+
 	lowers, err := ioutil.ReadFile(path.Join(dir, lowerFile))
 	if err != nil && !os.IsNotExist(err) {
 		return "", err