dns_zone: add support for diff and check modes

library/dns_zone.py

@@ -308,6 +308,41 @@ def zones_eq(lhs: dns.zone.Zone, rhs: dns.zone.Zone) -> bool:
     )
 
 
+def write_text_file(path, text, module):
+    """Naive text file write function with support for Ansible's diff and
+    check modes."""
+    diff_text = {
+        "before_header": f"{path} (content)",
+        "after_header": f"{path} (content)",
+        "after": text,
+    }
+
+    try:
+        with open(path) as f:
+            current = f.read()
+        changed = text != current
+        diff_text["before"] = current
+    except Exception:
+        changed = True
+        diff_text["before"] = None
+
+    if changed and not module.check_mode:
+        with open(path, "w") as f:
+            f.write(text)
+
+    file_args = module.load_file_common_arguments(module.params)
+    diff_attrs = {
+        "before_header": f"{path} (attributes)",
+        "after_header": f"{path} (attributes)",
+    }
+
+    changed = module.set_file_attributes_if_different(
+        file_args, changed, diff_attrs
+    )
+
+    return changed, [diff_text, diff_attrs]
+
+
 def main() -> int:
 
     record_types = {
@@ -345,6 +380,7 @@ def main() -> int:
     module = AnsibleModule(
         argument_spec=module_args,
         add_file_common_args=True,
+        supports_check_mode=True,
     )
 
     origin = dns.name.from_text(module.params["origin"])
@@ -352,11 +388,6 @@ def main() -> int:
 
     zone = dns.zone.Zone(origin)
 
-    try:
-        current = dns.zone.from_file(path, origin=origin)
-    except Exception:
-        current = None
-
     records = itertools.chain(
         make_records(module.params["soa"], SOA),
         make_reverse_hosts_records(module.params["reverse_hosts"]),
@@ -375,15 +406,11 @@ def main() -> int:
         dataset = node.get_rdataset(rdata.rdclass, rdata.rdtype, create=True)
         dataset.add(rdata)
 
-    file_args = module.load_file_common_arguments(module.params)
+    zone_text = zone.to_text(relativize=False, sorted=True)
 
-    changed = current is None or not zones_eq(zone, current)
-    if changed:
-        zone.to_file(module.params["path"], relativize=False, sorted=True)
+    changed, diff = write_text_file(path, zone_text, module)
 
-    changed = module.set_fs_attributes_if_different(file_args, changed)
-
-    module.exit_json(changed=changed)
+    module.exit_json(changed=changed, diff=diff)
 
     return 0