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cmd/order/amqp.go

@@ -13,31 +13,59 @@ import (
 	amqp "github.com/rabbitmq/amqp091-go"
 )
 
-// rabbitPublisher implements order.Publisher for the amqp_emit flow hook.
+// rabbitPublisher is the broker-delivery side used by the outbox relay. It dials
+// lazily and reconnects on failure, so the relay can be started even when the
+// broker is down at boot: messages accumulate durably in the outbox and drain
+// once the broker is reachable.
 type rabbitPublisher struct {
+	url  string
+	mu   sync.Mutex
 	conn *amqp.Connection
 	ch   *amqp.Channel
-	mu   sync.Mutex
 }
 
-func newRabbitPublisher(url string) (*rabbitPublisher, error) {
-	conn, err := amqp.Dial(url)
+func newRabbitPublisher(url string) *rabbitPublisher {
+	return &rabbitPublisher{url: url}
+}
+
+func (p *rabbitPublisher) connect() error {
+	conn, err := amqp.Dial(p.url)
 	if err != nil {
-		return nil, err
+		return err
 	}
 	ch, err := conn.Channel()
 	if err != nil {
 		_ = conn.Close()
-		return nil, err
+		return err
 	}
-	return &rabbitPublisher{conn: conn, ch: ch}, nil
+	p.conn, p.ch = conn, ch
+	return nil
+}
+
+func (p *rabbitPublisher) reset() {
+	if p.ch != nil {
+		_ = p.ch.Close()
+	}
+	if p.conn != nil {
+		_ = p.conn.Close()
+	}
+	p.ch, p.conn = nil, nil
 }
 
 func (p *rabbitPublisher) Publish(exchange, routingKey string, body []byte) error {
 	p.mu.Lock()
 	defer p.mu.Unlock()
-	return p.ch.PublishWithContext(context.Background(), exchange, routingKey, false, false,
+	if p.ch == nil {
+		if err := p.connect(); err != nil {
+			return err
+		}
+	}
+	err := p.ch.PublishWithContext(context.Background(), exchange, routingKey, false, false,
 		amqp.Publishing{ContentType: "application/json", Body: body})
+	if err != nil {
+		p.reset() // force a reconnect on the next attempt
+	}
+	return err
 }
 
 // This ingester lets the order service supersede the legacy go-order-manager: