Add support for unionfsbaserock/adamcoldrick/use-overlayfs-when-deploying

Overlayfs is new in version 3.18 of the kernel, so add support for a
different implementation of a union/overlay filesystem in order to
allow morph to work on older kernels.

1 files changed, 17 insertions, 0 deletions

diff --git a/morphlib/fsutils.py b/morphlib/fsutils.py
index 97a7a8f2..3a9ee4db 100644
--- a/morphlib/fsutils.py
+++ b/morphlib/fsutils.py
@@ -60,6 +60,23 @@ def mount(runcmd, partition, mount_point,
     runcmd(['mount', partition, mount_point] + fstype + options)
 
 
+def overlay_mount(runcmd, partition, mount_point,
+                  lowerdir, upperdir, workdir, settings): # pragma: no cover
+    method = settings['union-filesystem']
+    if method == 'overlayfs':
+        options = '-olowerdir=%s,upperdir=%s,workdir=%s' % \
+            (lowerdir, upperdir, workdir)
+        mount(runcmd, partition, mount_point, 'overlay', options)
+    elif method == 'unionfs':
+        if not os.path.exists(mount_point):
+            os.mkdir(mount_point)
+        dir_string = '%s=RW:%s=RO' % (upperdir, lowerdir)
+        runcmd(['unionfs', '-o', 'cow', dir_string, mount_point])
+    else:
+        raise cliapp.AppException('Union filesystem %s not supported' %
+                                  method)
+
+
 def unmount(runcmd, mount_point): # pragma: no cover
     runcmd(['umount', mount_point])