encore-go-pubsub

Encore Go Pub/Sub

Instructions

Pub/Sub is for asynchronous messaging between services. Producers publish events to a Topic; consumers attach Subscriptions to react. Resources must be declared as package-level variables — never inside functions.

Topics

package events
 
import "encore.dev/pubsub"
 
type OrderCreatedEvent struct {
    OrderID string `json:"order_id"`
    UserID  string `json:"user_id"`
    Total   int    `json:"total"`
}

Publishing

Subscriptions

Topic References

Pass topic access to library code while maintaining static analysis:

Delivery Guarantees

• pubsub.AtLeastOnce (default): may deliver duplicates → handlers must be idempotent.
• pubsub.ExactlyOnce: stricter, capped throughput (AWS 300 msg/s/topic, GCP 3000+ msg/s/region). Does not deduplicate on the publish side.

Guidelines

• Topics and subscriptions must be declared as package-level variables.
• Subscription handlers must be idempotent (at-least-once delivery is the default).
• Subscription handlers receive a context.Context and the event pointer; return an error to retry per the topic's retry policy.
• Don't do heavy synchronous work in Publish callers — Publish returns once the message is queued.