Added code to fetch key

src/ziggurat/header_transformer.clj

@@ -1,17 +1,17 @@
 (ns ziggurat.header-transformer
-  (:import [org.apache.kafka.streams.kstream ValueTransformer]
+  (:import [org.apache.kafka.streams.kstream ValueTransformerWithKey]
            [org.apache.kafka.streams.processor ProcessorContext]))
 
-(deftype HeaderTransformer [^{:volatile-mutable true} processor-context] ValueTransformer
+(deftype HeaderTransformer [^{:volatile-mutable true} processor-context] ValueTransformerWithKey
          (^void init [_ ^ProcessorContext context]
            (set! processor-context context))
-         (transform [_ record-value]
+         (transform [_ record-key record-value]
            (let [topic     (.topic processor-context)
                  timestamp (.timestamp processor-context)
                  partition (.partition processor-context)
                  headers   (.headers processor-context)
                  metadata  {:topic topic :timestamp timestamp :partition partition}]
-             {:value record-value :headers headers :metadata metadata}))
+             {:value record-value :headers headers :metadata metadata :key record-key}))
          (close [_] nil))
 
 (defn create []

src/ziggurat/streams.clj

@@ -16,7 +16,7 @@
            [org.apache.kafka.common.errors TimeoutException]
            [org.apache.kafka.streams KafkaStreams KafkaStreams$State StreamsConfig StreamsBuilder Topology]
            [org.apache.kafka.streams.errors StreamsUncaughtExceptionHandler StreamsUncaughtExceptionHandler$StreamThreadExceptionResponse]
-           [org.apache.kafka.streams.kstream JoinWindows ValueMapper TransformerSupplier ValueJoiner ValueTransformerSupplier]
+           [org.apache.kafka.streams.kstream JoinWindows ValueMapper TransformerSupplier ValueJoiner ValueTransformerWithKeySupplier]
            [ziggurat.timestamp_transformer IngestionTimeExtractor]))
 
 (def default-config-for-stream
@@ -77,7 +77,7 @@
 
 (defn- header-transformer-supplier
   []
-  (reify ValueTransformerSupplier
+  (reify ValueTransformerWithKeySupplier
     (get [_] (header-transformer/create))))
 
 (defn- timestamp-transform-values [topic-entity-name oldest-processed-message-in-s stream-builder]
@@ -123,9 +123,11 @@
     (close-stream topic-entity stream)))
 
 (defn- mapped-handler-fn [handler-fn channels message topic-entity]
+  (log/debug (format "See my message - %s", message))
   (try
     ((mapper-func handler-fn channels)
      (-> (->MessagePayload (:value message) topic-entity)
+         (assoc :key (:key message))
          (assoc :headers (:headers message))
          (assoc :metadata (:metadata message))))
     (finally)))

test/ziggurat/header_transformer_test.clj

@@ -17,8 +17,8 @@
                             (partition [_] partition))
           transformer     (create)
           _               (.init transformer context)
-          transformed-val (.transform transformer "val")]
-      (is (= {:value "val" :headers headers :metadata {:topic topic :timestamp timestamp :partition partition}} transformed-val))))
+          transformed-val (.transform transformer "key" "val")]
+      (is (= {:key "key" :value "val" :headers headers :metadata {:topic topic :timestamp timestamp :partition partition}} transformed-val))))
 
   (testing "transforms value with nil headers when not passed"
     (let [topic           "topic"
@@ -31,5 +31,5 @@
                             (partition [_] partition))
           transformer     (create)
           _               (.init transformer context)
-          transformed-val (.transform transformer "val")]
-      (is (= {:value "val" :headers nil :metadata {:topic topic :timestamp timestamp :partition partition}} transformed-val)))))
+          transformed-val (.transform transformer "key" "val")]
+      (is (= {:key "key" :value "val" :headers nil :metadata {:topic topic :timestamp timestamp :partition partition}} transformed-val)))))