cli/prune: fix a possible infinite recursion

With recursive instances, it was possible that the slapos.cfg introduce a
kind of loop and this was checking again and again the same folders.

Fix this by keeping track of the visited instance root and not visit the
same instance root twice.

slapos/cli/prune.py

@@ -92,7 +92,7 @@ def _prune(
       logger, software_root, shared_root, ignored_shared_parts)
 
   # recursively look in instance
-  signatures.update(getUsageSignaturesFromSubInstance(logger, instance_root))
+  signatures.update(getUsageSignaturesFromSubInstance(logger, instance_root, set([])))
 
   for shared_part in glob.glob(os.path.join(shared_root, '*', '*')):
     if shared_part not in ignored_shared_parts:
@@ -140,7 +140,7 @@ def do_prune(logger, options, dry_run):
   )
 
 
-def getUsageSignaturesFromSubInstance(logger, instance_root):
+def getUsageSignaturesFromSubInstance(logger, instance_root, visited):
   """Look at instances in instance_root to find used shared parts,
   if instances are recursive slapos.
 
@@ -148,6 +148,11 @@ def getUsageSignaturesFromSubInstance(logger, instance_root):
   this is a recursive slapos.
   """
   signatures = {}
+  # prevent infinite loops
+  if instance_root in visited:
+    return signatures
+  visited.add(instance_root)
+
   for slapos_cfg in getInstanceSlaposCfgList(logger, instance_root):
     cfg = readSlaposCfg(logger, slapos_cfg)
     if not cfg:
@@ -181,7 +186,7 @@ def getUsageSignaturesFromSubInstance(logger, instance_root):
       )
     else:
       signatures.update(
-          getUsageSignaturesFromSubInstance(logger, cfg['instance_root']))
+          getUsageSignaturesFromSubInstance(logger, cfg['instance_root'], visited))
   return signatures
 
 

slapos/tests/test_prune.py

@@ -285,6 +285,44 @@ shared_part_list = NOT EXIST SHARED PART
 software_root = {instance_software}
 instance_root = anything
 shared_part_list = anything
+'''.format(**locals()))
+
+    do_prune(self.logger, self.config, False)
+    self.assertTrue(os.path.exists(used_in_software_from_instance))
+
+  def test_recursive_instance_multiple_levels(self):
+    used_in_software_from_instance = self._createSharedPart('used_in_software_from_instance')
+
+    instance_level1 = os.path.join(self.instance_root, 'slappart0')
+    instance_level1_etc = os.path.join(instance_level1, 'etc')
+    os.makedirs(instance_level1_etc)
+    instance_level1_slapos_cfg = os.path.join(instance_level1_etc, 'slapos.cfg')
+    with open(instance_level1_slapos_cfg, 'w') as f:
+      f.write('''
+[slapos]
+software_root = anything
+instance_root = {instance_level1}
+shared_part_list = anything
+'''.format(**locals()))
+
+    instance_level2 = os.path.join(instance_level1, 'srv', 'runner')
+    instance_level2_etc = os.path.join(instance_level2, 'etc')
+    os.makedirs(instance_level2_etc)
+    instance_level2_software = os.path.join(instance_level2, 'software')
+    os.makedirs(instance_level2_software)
+    software_in_instance = self._createFakeSoftware(
+        'soft_in_instance_level2',
+        using=used_in_software_from_instance,
+        software_root=instance_level2_software
+    )
+
+    instance_level2_slapos_cfg = os.path.join(instance_level2_etc, 'slapos.cfg')
+    with open(instance_level2_slapos_cfg, 'w') as f:
+      f.write('''
+[slapos]
+software_root = {instance_level2_software}
+instance_root = {instance_level2}
+shared_part_list = anything
 '''.format(**locals()))
 
     do_prune(self.logger, self.config, False)