Use overlayfs when building systems

This will allow us to cache systems as a list of chunks and a small
filesystem delta, rather than a massive tarball.

Change-Id: Ic5182137ddd88dc9679e0941550d08954cb4d306

1 files changed, 8 insertions, 0 deletions

diff --git a/morphlib/stagingarea.py b/morphlib/stagingarea.py
index 8c2781aa..ae11dea7 100644
--- a/morphlib/stagingarea.py
+++ b/morphlib/stagingarea.py
@@ -87,6 +87,14 @@ class StagingArea(object):
 
         return self._dir_for_source(source, 'inst')
 
+    def overlay_upperdir(self, source):
+        '''Create a directory to be upperdir for overlayfs, and return it.'''
+        return self._dir_for_source(source, 'overlay_upper')
+
+    def overlaydir(self, source):
+        '''Create a directory to be a mount point for overlayfs, return it'''
+        return self._dir_for_source(source, 'overlay')
+
     def relative(self, filename):
         '''Return a filename relative to the staging area.'''