Andrea Cosentino created CAMEL-23142:
----------------------------------------
Summary: camel-google-pubsub: Add maxDeliveryAttempts enforcement
to prevent infinite redelivery loops
Key: CAMEL-23142
URL: https://issues.apache.org/jira/browse/CAMEL-23142
Project: Camel
Issue Type: New Feature
Components: camel-google-pubsub
Reporter: Andrea Cosentino
Assignee: Andrea Cosentino
Fix For: 4.19.0
When a Google Pub/Sub subscription is configured with a dead-letter policy and
short retry delays (e.g., {{--min-retry-delay=5s}}, {{--max-retry-delay=15s}}),
the camel-google-pubsub consumer enters an infinite redelivery loop. The
component exposes the per-message delivery attempt count via the
{{CamelGooglePubsubDeliveryAttempt}} header, but has no mechanism to compare it
against the subscription's {{maxDeliveryAttempts}} threshold and short-circuit
processing.
The consumer keeps processing the same failing message in a tight loop until
Pub/Sub's server-side enforcement eventually routes it to the DLQ. With short
retry windows, this causes unnecessary load and resource consumption.
Increasing {{--min-retry-delay}} to 30s+ alleviates the symptom but does not
address the root cause.
h3. Example subscription configuration that triggers the issue
{code}
gcloud pubsub subscriptions create publisher-subscription
--topic=publisher-topic
--ack-deadline=10
--dead-letter-topic=publisher-topic-dlq
--max-delivery-attempts=5
--min-retry-delay=5s
--max-retry-delay=15s
{code}
Implementation:
Add a {{maxDeliveryAttempts}} endpoint parameter to the consumer. When the
delivery attempt count of an incoming message reaches the configured maximum,
the consumer automatically nacks the message without processing it, allowing
Pub/Sub to route it to the dead-letter topic.
The value is resolved as follows:
If explicitly set via the endpoint URI (e.g., {{?maxDeliveryAttempts=5}}), that
value is used.
If not explicitly set, the component auto-fetches the value from the
subscription's dead-letter policy at consumer startup using
{{SubscriptionAdminClient}}.
If auto-fetch fails (insufficient permissions, no dead-letter policy, emulator
limitations), enforcement is disabled and a warning is logged.
A value of {{0}} disables enforcement (default, preserving backward
compatibility).
Enforcement applies to both asynchronous and synchronous pull modes.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
