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| 1 | +package outbox |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "encoding/json" |
| 6 | + "fmt" |
| 7 | + "os" |
| 8 | + "strings" |
| 9 | + "time" |
| 10 | + |
| 11 | + "github.com/segmentio/kafka-go" |
| 12 | +) |
| 13 | + |
| 14 | +type kafkaWriter interface { |
| 15 | + WriteMessages(ctx context.Context, msgs ...kafka.Message) error |
| 16 | +} |
| 17 | + |
| 18 | +type kafkaWriterFactory func(brokers []string, topic string, ack kafka.RequiredAcks) kafkaWriter |
| 19 | + |
| 20 | +type kafkaPublisherConfig struct { |
| 21 | + brokers []string |
| 22 | + topicMapping map[string]string |
| 23 | + defaultAck kafka.RequiredAcks |
| 24 | + topicAcks map[string]kafka.RequiredAcks |
| 25 | +} |
| 26 | + |
| 27 | +// KafkaPublisher routes selected outbox topics to Kafka while preserving an |
| 28 | +// HTTP fallback for unconfigured topics. |
| 29 | +type KafkaPublisher struct { |
| 30 | + brokers []string |
| 31 | + topicMapping map[string]string |
| 32 | + topicAcks map[string]kafka.RequiredAcks |
| 33 | + defaultAck kafka.RequiredAcks |
| 34 | + writerFactory kafkaWriterFactory |
| 35 | + fallback Publisher |
| 36 | +} |
| 37 | + |
| 38 | +func NewKafkaPublisher(brokers []string, topicMapping map[string]string, fallback Publisher) *KafkaPublisher { |
| 39 | + return &KafkaPublisher{ |
| 40 | + brokers: append([]string(nil), brokers...), |
| 41 | + topicMapping: cloneTopicMapping(topicMapping), |
| 42 | + topicAcks: map[string]kafka.RequiredAcks{}, |
| 43 | + defaultAck: kafka.RequireOne, |
| 44 | + writerFactory: newKafkaWriter, |
| 45 | + fallback: fallback, |
| 46 | + } |
| 47 | +} |
| 48 | + |
| 49 | +func NewKafkaPublisherFromEnv(fallback Publisher) (*KafkaPublisher, error) { |
| 50 | + cfg, err := parseKafkaConfigFromEnv() |
| 51 | + if err != nil { |
| 52 | + return nil, err |
| 53 | + } |
| 54 | + |
| 55 | + pub := NewKafkaPublisher(cfg.brokers, cfg.topicMapping, fallback) |
| 56 | + pub.defaultAck = cfg.defaultAck |
| 57 | + pub.topicAcks = cfg.topicAcks |
| 58 | + return pub, nil |
| 59 | +} |
| 60 | + |
| 61 | +func (p *KafkaPublisher) Publish(ctx context.Context, event *Event) error { |
| 62 | + if event == nil { |
| 63 | + return fmt.Errorf("kafka publisher received nil event") |
| 64 | + } |
| 65 | + |
| 66 | + topic, ok := p.resolveTopic(event) |
| 67 | + if !ok { |
| 68 | + if p.fallback != nil { |
| 69 | + return p.fallback.Publish(ctx, event) |
| 70 | + } |
| 71 | + return nil |
| 72 | + } |
| 73 | + |
| 74 | + if len(p.brokers) == 0 { |
| 75 | + return fmt.Errorf("kafka publisher has no brokers configured") |
| 76 | + } |
| 77 | + |
| 78 | + writer := p.writerFactory(p.brokers, topic, p.resolveAck(topic)) |
| 79 | + if writer == nil { |
| 80 | + return fmt.Errorf("kafka publisher writer factory returned nil") |
| 81 | + } |
| 82 | + |
| 83 | + payload := map[string]interface{}{ |
| 84 | + "id": event.ID, |
| 85 | + "type": event.EventType, |
| 86 | + "data": event.EventData, |
| 87 | + "occurred_at": event.OccurredAt, |
| 88 | + "aggregate_id": safeString(event.AggregateID), |
| 89 | + "aggregate_type": safeString(event.AggregateType), |
| 90 | + "version": event.Version, |
| 91 | + } |
| 92 | + |
| 93 | + body, err := json.Marshal(payload) |
| 94 | + if err != nil { |
| 95 | + return fmt.Errorf("failed to marshal kafka payload: %w", err) |
| 96 | + } |
| 97 | + |
| 98 | + start := time.Now() |
| 99 | + err = writer.WriteMessages(ctx, kafka.Message{Key: []byte(event.ID.String()), Value: body}) |
| 100 | + latency := time.Since(start).Seconds() |
| 101 | + if OutboxKafkaProduceLatency != nil { |
| 102 | + OutboxKafkaProduceLatency.WithLabelValues(topic).Observe(latency) |
| 103 | + } |
| 104 | + if err != nil { |
| 105 | + if OutboxKafkaErrorsTotal != nil { |
| 106 | + OutboxKafkaErrorsTotal.WithLabelValues(topic, "publish_error").Inc() |
| 107 | + } |
| 108 | + return fmt.Errorf("kafka publish failed for topic %s: %w", topic, err) |
| 109 | + } |
| 110 | + |
| 111 | + return nil |
| 112 | +} |
| 113 | + |
| 114 | +func (p *KafkaPublisher) resolveTopic(event *Event) (string, bool) { |
| 115 | + if event == nil { |
| 116 | + return "", false |
| 117 | + } |
| 118 | + if topic, ok := p.topicMapping[event.EventType]; ok && topic != "" { |
| 119 | + return topic, true |
| 120 | + } |
| 121 | + if len(event.EventData) == 0 { |
| 122 | + return "", false |
| 123 | + } |
| 124 | + var eventData EventData |
| 125 | + if err := json.Unmarshal(event.EventData, &eventData); err == nil && eventData.Type != "" { |
| 126 | + if topic, ok := p.topicMapping[eventData.Type]; ok && topic != "" { |
| 127 | + return topic, true |
| 128 | + } |
| 129 | + } |
| 130 | + return "", false |
| 131 | +} |
| 132 | + |
| 133 | +func (p *KafkaPublisher) resolveAck(topic string) kafka.RequiredAcks { |
| 134 | + if ack, ok := p.topicAcks[topic]; ok { |
| 135 | + return ack |
| 136 | + } |
| 137 | + return p.defaultAck |
| 138 | +} |
| 139 | + |
| 140 | +func newKafkaWriter(brokers []string, topic string, ack kafka.RequiredAcks) kafkaWriter { |
| 141 | + return &kafka.Writer{ |
| 142 | + Addr: kafka.TCP(brokers...), |
| 143 | + Topic: topic, |
| 144 | + Balancer: &kafka.LeastBytes{}, |
| 145 | + RequiredAcks: ack, |
| 146 | + Compression: kafka.Snappy, |
| 147 | + WriteTimeout: 10 * time.Second, |
| 148 | + ReadTimeout: 10 * time.Second, |
| 149 | + AllowAutoTopicCreation: true, |
| 150 | + } |
| 151 | +} |
| 152 | + |
| 153 | +func parseKafkaConfigFromEnv() (kafkaPublisherConfig, error) { |
| 154 | + cfg := kafkaPublisherConfig{ |
| 155 | + defaultAck: kafka.RequireOne, |
| 156 | + topicAcks: map[string]kafka.RequiredAcks{}, |
| 157 | + } |
| 158 | + |
| 159 | + for _, broker := range strings.Split(os.Getenv("OUTBOX_KAFKA_BROKERS"), ",") { |
| 160 | + broker = strings.TrimSpace(broker) |
| 161 | + if broker != "" { |
| 162 | + cfg.brokers = append(cfg.brokers, broker) |
| 163 | + } |
| 164 | + } |
| 165 | + |
| 166 | + if topicMap := os.Getenv("OUTBOX_KAFKA_TOPIC_MAP"); topicMap != "" { |
| 167 | + cfg.topicMapping = map[string]string{} |
| 168 | + for _, entry := range strings.Split(topicMap, ",") { |
| 169 | + entry = strings.TrimSpace(entry) |
| 170 | + if entry == "" { |
| 171 | + continue |
| 172 | + } |
| 173 | + parts := strings.SplitN(entry, "=", 2) |
| 174 | + if len(parts) != 2 { |
| 175 | + return kafkaPublisherConfig{}, fmt.Errorf("invalid OUTBOX_KAFKA_TOPIC_MAP entry %q", entry) |
| 176 | + } |
| 177 | + cfg.topicMapping[strings.TrimSpace(parts[0])] = strings.TrimSpace(parts[1]) |
| 178 | + } |
| 179 | + } |
| 180 | + |
| 181 | + if ackValue := strings.TrimSpace(os.Getenv("OUTBOX_KAFKA_ACKS")); ackValue != "" { |
| 182 | + ack, err := parseKafkaAck(ackValue) |
| 183 | + if err != nil { |
| 184 | + return kafkaPublisherConfig{}, err |
| 185 | + } |
| 186 | + cfg.defaultAck = ack |
| 187 | + } |
| 188 | + |
| 189 | + if ackValue := strings.TrimSpace(os.Getenv("OUTBOX_KAFKA_TOPIC_ACKS")); ackValue != "" { |
| 190 | + for _, entry := range strings.Split(ackValue, ",") { |
| 191 | + entry = strings.TrimSpace(entry) |
| 192 | + if entry == "" { |
| 193 | + continue |
| 194 | + } |
| 195 | + parts := strings.SplitN(entry, "=", 2) |
| 196 | + if len(parts) != 2 { |
| 197 | + return kafkaPublisherConfig{}, fmt.Errorf("invalid OUTBOX_KAFKA_TOPIC_ACKS entry %q", entry) |
| 198 | + } |
| 199 | + ack, err := parseKafkaAck(strings.TrimSpace(parts[1])) |
| 200 | + if err != nil { |
| 201 | + return kafkaPublisherConfig{}, err |
| 202 | + } |
| 203 | + cfg.topicAcks[strings.TrimSpace(parts[0])] = ack |
| 204 | + } |
| 205 | + } |
| 206 | + |
| 207 | + return cfg, nil |
| 208 | +} |
| 209 | + |
| 210 | +func parseKafkaAck(value string) (kafka.RequiredAcks, error) { |
| 211 | + switch strings.ToLower(strings.TrimSpace(value)) { |
| 212 | + case "0", "none", "no_ack": |
| 213 | + return kafka.RequireNone, nil |
| 214 | + case "1", "one", "requireone": |
| 215 | + return kafka.RequireOne, nil |
| 216 | + case "all", "requireall", "-1": |
| 217 | + return kafka.RequireAll, nil |
| 218 | + default: |
| 219 | + return kafka.RequireOne, fmt.Errorf("unsupported kafka ack value %q", value) |
| 220 | + } |
| 221 | +} |
| 222 | + |
| 223 | +func cloneTopicMapping(mapping map[string]string) map[string]string { |
| 224 | + if len(mapping) == 0 { |
| 225 | + return map[string]string{} |
| 226 | + } |
| 227 | + cloned := make(map[string]string, len(mapping)) |
| 228 | + for key, value := range mapping { |
| 229 | + cloned[key] = value |
| 230 | + } |
| 231 | + return cloned |
| 232 | +} |
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