2026.2 Series Release Notes

18.3.1

Bug Fixes

  • Fixed a reply queue name collision with use_queue_manager = True. The QManager used to only rely on the process-group identity captured at object construction time to key the shared /dev/shm counter. When the process group changes after some oslo.messaging objects already exist – as happens under the cotyledon supervisor, whose master calls os.setsid() after creating them – a manager born in the master and a manager born in a worker disagreed on that identity and kept resetting the shared counter, so several processes built the same reply queue name (reply_<host>:<proc>:1) and stole each other’s RPC replies (leading to No calling threads waiting for msg_id and MessagingTimeout). The identity is now re-evaluated when the queue name is built. When the process group id is 0 (crun edge case) it falls back to the process id, as before. See bug 2110957.

18.3.0

New Features

  • Added OpenTelemetry distributed tracing support for RPC calls. When enabled, producer spans are created for call() and cast() on the client side, and consumer spans are created on the server side during message dispatch. Trace context is propagated across services via the W3C traceparent header carried inside the message context, allowing full end-to-end trace correlation from HTTP request through RabbitMQ to the RPC backend. The feature is disabled by default and can be enabled with:

    [oslo_messaging_tracing]
tracing_enabled = true
tracing_service_name = nova
otel_exporter_otlp_endpoint = http://localhost:4318
otlp_protocol = http/protobuf

    The OTLP transport protocol can be set to http/protobuf (default) or grpc. The corresponding exporter package must be installed:

    pip install oslo.messaging[tracing-http]   # for HTTP/protobuf
pip install oslo.messaging[tracing-grpc]   # for gRPC

18.2.0

Upgrade Notes

  • The RabbitMQ driver now enforces verification of the broker hostnames when ssl_ca_file is set and transport_url contanims muleiple RabbitMQ servers. The [oslo_messaging_rabbit] oslo_messaging_rabbit has no effect now.

18.1.0

Deprecation Notes

  • The oslo_messaging.version module and associated objects has been deprecated for removal. Prefer use of importlib.metadata to inspect version information for installed packages.

Security Issues

  • Under TLS with ssl_ca_file, oslo.messaging validated the broker certificate chain but did not verify the RabbitMQ broker hostname. A man-in-the-middle attacker with a certificate trusted by that CA could impersonate the broker.

    The RabbitMQ driver now verifies the broker hostname when ssl_ca_file is set and [oslo_messaging_rabbit] ssl_enforce_hostname_verification is enabled. Using ssl=true without ssl_ca_file still does not verify the broker hostname.

    The ssl_enforce_hostname_verification option is deprecated and scheduled for removal after deployments finish migrating; hostname verification should remain enabled.

    For transport URLs with multiple brokers and hostname verification enabled, Kombu 5.2.0 or newer substitutes the active broker hostname for TLS. Older Kombu versions log a warning and use the first configured broker hostname as a best effort; operators should upgrade Kombu or use a certificate (SAN or wildcard) that covers all configured broker hostnames.

18.0.0

Upgrade Notes

  • The deprecated heartbeat_in_pthread option in the [oslo_messaging_rabbit] section has been removed. Operators should remove this option from their configuration files.