Implement override and reset analog to docker-compose (https://docs.d…

…ocker.com/compose/compose-file/13-merge/)

Signed-off-by: Sebastian Sellmeier <mail@sebastian-sellmeier.de>

podman_compose.py

@@ -1149,6 +1149,43 @@ def flat_deps(services, with_extends=False):
  for name, srv in services.items():
  rec_deps(services, name)
 
+###################
+# Override and reset tags
+###################
+
+class OverrideTag(yaml.YAMLObject):
+ yaml_tag = u'!override'
+
+ def __init__(self, value):
+ self.value = value
+
+ def __repr__(self):
+ return self.value
+
+ @classmethod
+ def from_yaml(cls, loader, node):
+ return OverrideTag(node.value)
+
+ @classmethod
+ def to_yaml(cls, dumper, data):
+ return dumper.represent_scalar(cls.yaml_tag, data.value)
+
+class ResetTag(yaml.YAMLObject):
+ yaml_tag = u'!reset'
+
+ def __repr__(self):
+ return
+
+ @classmethod
+ def from_yaml(cls, loader, node):
+ return ResetTag()
+
+ @classmethod
+ def to_yaml(cls, dumper, data):
+ return
+
+yaml.SafeLoader.add_constructor(OverrideTag.yaml_tag, OverrideTag.from_yaml)
+yaml.SafeLoader.add_constructor(ResetTag.yaml_tag, ResetTag.from_yaml)
 
 ###################
 # podman and compose classes
@@ -1330,6 +1367,8 @@ def rec_merge_one(target, source):
  update target from source recursively
  """
  done = set()
+ remove = set()
+
  for key, value in source.items():
  if key in target:
  continue
@@ -1340,10 +1379,18 @@ def rec_merge_one(target, source):
  continue
  if key not in source:
  continue
+
  value2 = source[key]
+
  if key in ("command", "entrypoint"):
  target[key] = clone(value2)
  continue
+ if isinstance(value, ResetTag) or isinstance(value2, ResetTag):
+ remove.add(key)
+ continue
+ if isinstance(value, OverrideTag) or isinstance(value2, OverrideTag):
+ target[key] = clone(value.value) if isinstance(value, OverrideTag) else clone(value2.value)
+ continue
  if not isinstance(value2, type(value)):
  value_type = type(value)
  value2_type = type(value2)
@@ -1368,6 +1415,10 @@ def rec_merge_one(target, source):
  rec_merge_one(value, value2)
  else:
  target[key] = value2
+
+ for key in remove:
+ del target[key]
+
  return target