fix: Support multi-transport queue name parsing for MassTransit

[tippmar-nr]

Summary

Resolves #3519. MassTransit's Kafka transport (and other non-RabbitMQ transports) reported queue names as Unknown with destination type Queue instead of Topic.

Root causes:

• GetQueueData() only understood RabbitMQ-style underscore-delimited URIs
• NewRelicFilter used SourceAddress exclusively, which for Kafka Rider is the bus endpoint (no queue/topic info)
• The consume path in both wrappers hardcoded MessageBrokerDestinationType.Queue

Fixes:

• Rewrote GetQueueData() as a scheme-aware parser supporting all MassTransit transports (Kafka, RabbitMQ, Azure Service Bus, Amazon SQS, ActiveMQ, InMemory)
• Added fallback to DestinationAddress when SourceAddress yields Unknown — handles Kafka Rider where SourceAddress is the bus endpoint
• Detect MassTransit Rider path prefixes (/kafka/, /event-hub/) regardless of bus transport scheme
• Fixed hardcoded MessageBrokerDestinationType.Queue in the consume path of both modern and legacy NewRelicFilter

Tests:

• 54 unit tests covering all transport URI formats, fallback behavior, and Rider prefix detection
• New multi-transport container integration test exercising Kafka, RabbitMQ, and InMemory transports simultaneously
• Updated existing MassTransit integration test regex for compatibility with the new parser

Test plan

• Unit tests pass (54 tests)
• FullAgent.sln builds
• Container integration test: MassTransitDotNet10Test
• Container integration test: MassTransitDotNet8Test
• Existing MassTransit integration tests (StartHost/StartBus variants)
• CI pipeline

[tippmar-nr]

MassTransit URI Format Reference for GetQueueData()

This document maps each MassTransit transport URI format to its source code in the MassTransit repo and shows how our GetQueueDataFromUri() implementation handles it.

Agent source: src/Agent/NewRelic/Agent/Extensions/NewRelic.Agent.Extensions/Helpers/MassTransit.cs (branch fix/masstransit-multi-transport-queue-parsing)

---

1. RabbitMQ

MassTransit source: RabbitMqEndpointAddress.cs

Schemes: rabbitmq, rabbitmqs (SSL, verified), amqp, amqps

URI format:

rabbitmq://host/{name}                          (default vhost "/")
rabbitmq://host/{vhost}/{name}                  (named vhost)
rabbitmq://host/{vhost}/{Hostname}_{AppName}_bus_{id}?temporary=true   (auto-generated bus endpoint)
rabbitmqs://host/{vhost}/{name}                 (SSL connection, port 5671)

Our parsing (ParseRabbitMqUri): Splits by _ to extract the last segment (e.g. the random id suffix). If no underscores, falls back to last path segment. Checks ?temporary=true for temp queue detection.

Query params: temporary, durable, autodelete, type, bind, queue, delayedtype, alternateexchange, bindexchange, singleactiveconsumer

---

2. Kafka Rider

MassTransit source: KafkaTopicAddress.cs

Scheme: Inherits from host bus (NOT kafka://) -- this is the critical distinction

PathPrefix constant: "kafka"

URI format:

{bus-scheme}://host/kafka/{topic}

Examples:

loopback://localhost/kafka/my-topic          (InMemory bus + Kafka Rider)
rabbitmq://broker/kafka/my-topic             (RabbitMQ bus + Kafka Rider)

Our parsing (TryParseRiderPrefix): Checks AbsolutePath for kafka/ prefix before any scheme-specific parsing. Strips the prefix and sets DestinationType = Topic. This runs early in the parsing pipeline so it takes priority over scheme-specific handlers.

Note: The kafka:// scheme is also handled in the scheme switch as a fallback, but MassTransit does not currently generate this format.

---

3. Azure Event Hubs Rider

MassTransit source: EventHubEndpointAddress.cs

Scheme: Inherits from host bus

PathPrefix constant: "event-hub" (verified: public const string PathPrefix = "event-hub")

URI format:

{bus-scheme}://host/event-hub/{hub-name}
sb://namespace.servicebus.windows.net/event-hub/{hub-name}

Our parsing (TryParseRiderPrefix): Same early check for event-hub/ prefix. Strips prefix, sets DestinationType = Topic. Also handled in ParseServiceBusUri for the sb:// scheme case.

---

4. Azure Service Bus

MassTransit source: ServiceBusEndpointAddress.cs

Scheme: sb

URI format:

sb://namespace.servicebus.windows.net/{name}                (no scope)
sb://namespace.servicebus.windows.net/{scope}/{name}        (with scope)
sb://namespace.servicebus.windows.net/{name}?type=topic     (topic)

Our parsing (ParseServiceBusUri): First checks for event-hub/ path prefix (Event Hubs Rider over SB transport). Otherwise extracts last path segment. Uses ?type=topic query param for destination type. Treats ?autodelete as temp queue.

Query params: autodelete (seconds), type (queue or topic)

---

5. Amazon SQS

MassTransit source: AmazonSqsEndpointAddress.cs

Scheme: amazonsqs

URI format:

amazonsqs://region/{name}                       (no scope)
amazonsqs://region/{scope}/{name}               (with scope)
amazonsqs://region/{name}?type=topic            (SNS topic)

Our parsing (scheme switch): Extracts last path segment. Checks ?type=topic for topic detection. Checks ?temporary=true for temp queue.

Query params: durable, autodelete, temporary, type

---

6. ActiveMQ

MassTransit source: ActiveMqEndpointAddress.cs

Schemes: activemq, amqp (shared with RabbitMQ -- but amqp is handled in our ActiveMQ branch, while rabbitmq has its own parser)

URI format:

activemq://host/{name}                          (default vhost "/")
activemq://host/{vhost}/{name}                  (named vhost)
activemq://host/{name}?type=topic               (topic destination)

Default port: 61616 (omitted from URI)

Our parsing (scheme switch): Extracts last path segment. Checks ?type=topic for topic detection. Checks ?temporary=true for temp queue.

Query params: durable, autodelete, temporary, type

Note on amqp/amqps ambiguity: Both RabbitMQ and ActiveMQ can use amqp:// scheme. Our code handles amqp/amqps in the ActiveMQ branch (last-path-segment extraction), not the RabbitMQ branch (underscore splitting). This is correct because the underscore-delimited naming is a RabbitMQ convention, and amqp:// URIs from either transport work fine with last-path-segment extraction.

---

7. InMemory / Loopback

MassTransit source: InMemoryEndpointAddress.cs

Scheme: loopback

URI format:

loopback://localhost/{name}                     (default vhost "/")
loopback://localhost/{vhost}/{name}             (named vhost)

Our parsing (scheme switch): Extracts last path segment. No temp queue detection (InMemory doesn't support persistent queues).

Query params: bind, queue, type (exchange type)

---

8. SQL Transport

MassTransit source: SqlEndpointAddress.cs, SqlHostAddress.cs

Scheme: db (verified: public const string DbScheme = "db" in SqlHostAddress.cs)

URI format:

db://host/{virtualhost}/{name}                  (queue)
db://host/{virtualhost}.{area}/{name}           (queue with area/scope)
db://host/{virtualhost}/{name}?type=topic       (topic)

Our parsing: No explicit case "db": — falls through to default, which calls GetLastPathSegment(). This correctly extracts the queue name. However, ?type=topic and ?autodelete query params are not evaluated in the default branch, so SQL transport topics would be reported as Queue instead of Topic, and auto-delete queues would not be detected as TempQueue.

Query params: autodelete, type, instance

---

9. WebJobs Transports

MassTransit source: MassTransit.WebJobs.EventHubsIntegration/ and MassTransit.WebJobs.ServiceBusIntegration/

These are Azure Functions (WebJobs) bindings for Event Hubs and Service Bus. They do not define their own endpoint address classes — they reuse the address classes from their parent transports (EventHubEndpointAddress and ServiceBusEndpointAddress respectively). No additional URI formats to handle.

---

10. Short-form Addressing (All Transports)

MassTransit source: All endpoint address classes support short-form pseudo-schemes.

Schemes: queue, topic, exchange

URI format:

queue:{name}
topic:{name}
exchange:{name}

Our parsing (scheme switch, first priority): Detected by scheme before any transport-specific parsing. topic: sets DestinationType = Topic. queue: and exchange: set DestinationType = Queue.

Verification note: Short-form support was verified in the source for RabbitMQ, ActiveMQ, InMemory, SQS, and Service Bus address classes. It was not independently verified for Kafka or Event Hub address classes.

---

Unknown / Unrecognized URI Formats

Behavior: The default case in the scheme switch calls GetLastPathSegment(). If the URI has no usable path segments (e.g. loopback://localhost/ with just a trailing slash), GetLastPathSegment() returns "Unknown".

Null URI: If sourceAddress is null, the method returns immediately with the default MassTransitQueueData (QueueName = "Unknown", DestinationType = Queue).

Fallback address: GetQueueData(sourceAddress, fallbackAddress) tries the primary address first. If it results in "Unknown", it tries the fallback. This handles Kafka Rider consume scenarios where SourceAddress is the bus endpoint (e.g. loopback://localhost/) and DestinationAddress has the actual topic.

---

Parsing Priority Order

1. Null check -- returns "Unknown" immediately
2. Short-form schemes (topic:, queue:, exchange:) -- highest priority
3. Rider path prefixes (kafka/, event-hub/) -- checked before scheme-specific parsing, because Rider URIs inherit the bus transport scheme
4. Transport scheme (rabbitmq, sb, amazonsqs, activemq, loopback, etc.)
5. Default fallback -- last path segment extraction for any unrecognized scheme
6. Fallback address -- if primary yields "Unknown", tries the secondary URI

---

Exhaustive Transport Enumeration

All 10 transports under src/Transports/ in the MassTransit repo have been enumerated and analyzed:

Transport	Address class	Scheme / Prefix	Our handling
RabbitMQ	RabbitMqEndpointAddress	rabbitmq, rabbitmqs	ParseRabbitMqUri
ActiveMQ	ActiveMqEndpointAddress	activemq, amqp, amqps	scheme switch
Amazon SQS	AmazonSqsEndpointAddress	amazonsqs	scheme switch
Azure Service Bus	ServiceBusEndpointAddress	sb	ParseServiceBusUri
Kafka Rider	KafkaTopicAddress	path prefix kafka/	TryParseRiderPrefix
Event Hubs Rider	EventHubEndpointAddress	path prefix event-hub/	TryParseRiderPrefix
InMemory/Loopback	InMemoryEndpointAddress	loopback	scheme switch
SQL Transport	SqlEndpointAddress	db	default fallback
WebJobs.EventHubs	(no own address class)	reuses EventHubEndpointAddress	inherited
WebJobs.ServiceBus	(no own address class)	reuses ServiceBusEndpointAddress	inherited

No other Rider-style path prefixes exist beyond kafka/ and event-hub/.

---

Known Gaps

1. SQL transport ?type=topic and ?autodelete not evaluated: The db:// scheme falls through to the default branch, which extracts the queue name correctly via GetLastPathSegment() but does not check query params. SQL transport topics would be reported as Queue instead of Topic, and auto-delete queues would not be detected as TempQueue. This is a relatively new MassTransit feature with limited adoption.

2. Short-form pseudo-schemes for Kafka/Event Hub: The queue:, topic:, and exchange: short-form schemes were verified in the source for RabbitMQ, ActiveMQ, InMemory, SQS, and Service Bus. They were not independently verified in the Kafka or Event Hub address classes. Our code handles them regardless since the scheme check runs first, but the claim that "all endpoint address classes support short-form" is not fully verified.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 87.70492% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.77%. Comparing base (407eae5) to head (cbc925c).

Files with missing lines	Patch %	Lines
...s/NewRelic.Agent.Extensions/Helpers/MassTransit.cs	87.70%	11 Missing and 4 partials ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #3523    +/-   ##
========================================
  Coverage   81.77%   81.77%            
========================================
  Files         508      508            
  Lines       34235    34345   +110     
  Branches     4041     4061    +20     
========================================
+ Hits        27995    28086    +91     
- Misses       5275     5289    +14     
- Partials      965      970     +5     

Flag	Coverage Δ
Agent	82.76% <87.70%> (-0.01%)	⬇️
Profiler	71.75% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...s/NewRelic.Agent.Extensions/Helpers/MassTransit.cs	88.18% <87.70%> (-11.82%)	⬇️

... and 1 file with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[nrcventura]

It seems like this code should not throw an exception if it encounters a uri with an unexpected format. However, there is a lot of code to wade through, and the explanation from claude describing where the Uri structure is defined, doesn't seem to be accurate, or at least does not seem to be complete enough for me to understand the expected formats. From what I've seen in the MassTransit repo I do not think that this parsing covers all of the possibilities, but I do think that it is an improvement over what was previously there.