fix(ipv6-reboot): ignore Prometheus failures in node init

since this issuse was declared P4, we'll gonna ignore it
for now, since after one or two retries the node does sping
up

Ref: scylladb/scylladb#20387

sdcm/nemesis.py

@@ -91,6 +91,7 @@
     ignore_raft_transport_failing,
     decorate_with_context_if_issues_open,
     ignore_take_snapshot_failing,
+    ignore_ipv6_failure_to_assign,
 )
 from sdcm.sct_events.health import DataValidatorEvent
 from sdcm.sct_events.loaders import CassandraStressLogEvent, ScyllaBenchEvent
@@ -3937,6 +3938,9 @@ def _run_commands_wait_and_cleanup(  # pylint: disable=too-many-arguments
     @decorate_with_context([
         ignore_ycsb_connection_refused,
     ])
+    @decorate_with_context_if_issues_open(
+        ignore_ipv6_failure_to_assign,
+        issue_refs=['https://github.com/scylladb/scylladb/issues/20387'])
     def reboot_node(self, target_node, hard=True, verify_ssh=True):
         target_node.reboot(hard=hard, verify_ssh=verify_ssh)
         if self.tester.params.get('print_kernel_callstack'):

sdcm/sct_events/group_common_events.py

@@ -474,6 +474,22 @@ def ignore_take_snapshot_failing():
         yield
 
 
+@contextmanager
+def ignore_ipv6_failure_to_assign():
+    with ExitStack() as stack:
+        stack.enter_context(EventsSeverityChangerFilter(
+            new_severity=Severity.WARNING,
+            event_class=DatabaseLogEvent,
+            regex=r".*init - Startup failed:.*Cannot assign requested address",
+            extra_time_to_expiration=60))
+        stack.enter_context(EventsSeverityChangerFilter(
+            new_severity=Severity.WARNING,
+            event_class=DatabaseLogEvent,
+            regex=r".*init - Could not start Prometheus API server.*Cannot assign requested address",
+            extra_time_to_expiration=60))
+        yield
+
+
 def decorate_with_context(context_list: list[Callable | ContextManager] | Callable | ContextManager):
     """
     helper to decorate a function to run with a list of callables that return context managers