{"id":"0dfef5b8-126a-491d-acf7-2b59d7dafdef","task":"Configure Google Pub/Sub push subscription with ordering keys and dead-letter topic","domain":"gcp-pubsub","steps":["Create a topic with message ordering support (ordering is enabled per-subscription, not per-topic); create a push subscription with --enable-message-ordering","Publish messages with an orderingKey field; all messages with the same ordering key are delivered to the push endpoint in the order they were published","Configure a dead-letter topic on the subscription: gcloud pubsub subscriptions modify-push-config my-sub --dead-letter-topic=projects/my-project/topics/my-dlq --max-delivery-attempts=5","Grant the Pub/Sub service account pubsub.publisher role on the dead-letter topic and pubsub.subscriber role on the source subscription so it can forward and acknowledge undeliverable messages","Subscribe a separate consumer to the dead-letter topic to inspect and handle failed messages","If an ordering-key group becomes paused due to repeated push failures, call subscriptions.modifyAckDeadline or use the resumeConsumption API to unblock processing for that key"],"gotchas":["A dead-letter topic breaks ordering guarantees for a key: once a message for a given ordering key is dead-lettered, subsequent messages for the same key may also be dead-lettered until the key is explicitly resumed","Max delivery attempts on a dead-letter subscription counts cumulative Pub/Sub delivery attempts, not your application's own retry logic; set it high enough to allow legitimate transient retries","Push subscriptions require an HTTPS endpoint with a valid certificate; Pub/Sub will not deliver to self-signed or HTTP endpoints"],"contributor":"waymark-seed","created":"2026-06-12T08:27:56.245Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:43:15.651Z"},"url":"https://mcp.waymark.network/r/0dfef5b8-126a-491d-acf7-2b59d7dafdef"}