add schema validator

use ConfigurationProperties instead of Value for configuration

src/main/kotlin/com/example/demo/config/AppConfig.kt

@@ -9,17 +9,19 @@ import com.example.demo.services.database.city.CityServiceImpl
 import com.example.demo.services.database.product.ProductService
 import com.example.demo.services.database.product.ProductServiceImpl
 import com.example.demo.services.kafka.Producer
+import com.example.demo.services.kafka.SchemaValidator
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.SerializationFeature
 import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule
 import org.springframework.beans.factory.annotation.Autowired
-import org.springframework.beans.factory.annotation.Value
+import org.springframework.boot.context.properties.EnableConfigurationProperties
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
+
 @Configuration
+@EnableConfigurationProperties(KafkaProperties::class)
 class AppConfig(
-    @Value("\${kafka.producer.product.default-sync-topic}")
-    private val defaultProductSyncTopic: String
+    @Autowired private val kafkaProperties: KafkaProperties,
 ) {
     @Bean
     fun objectMapper(): ObjectMapper {
@@ -38,12 +40,15 @@ class AppConfig(
         @Autowired productRepository: ProductRepository,
         @Autowired producer: Producer,
     ): ProductService = ProductServiceImpl(
-        defaultProductSyncTopic,
+        kafkaProperties.producer.product.defaultSyncTopic,
         productRepository,
         producer,
     )
 
     @Bean
     fun cityService(@Autowired cityRepository: CityRepository): CityService = CityServiceImpl(cityRepository)
+
+    @Bean
+    fun schemaValidator(): SchemaValidator = SchemaValidator(kafkaProperties.validation.schema)
 }
 

src/main/kotlin/com/example/demo/config/KafkaConsumerConfig.kt

@@ -5,7 +5,6 @@ import com.example.demo.services.kafka.Consumer
 import org.apache.kafka.clients.consumer.ConsumerConfig
 import org.apache.kafka.common.serialization.StringDeserializer
 import org.springframework.beans.factory.annotation.Autowired
-import org.springframework.beans.factory.annotation.Value
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
 import org.springframework.kafka.config.ConcurrentKafkaListenerContainerFactory
@@ -14,23 +13,18 @@ import org.springframework.kafka.core.DefaultKafkaConsumerFactory
 
 @Configuration
 class KafkaConsumerConfig(
-    @Value("\${kafka.bootstrap-servers}")
-    val servers: String,
-    @Value("\${kafka.consumer.group-id}")
-    val consumerGroup: String,
+    @Autowired val kafkaProperties: KafkaProperties
 ) {
     @Bean
     fun consumer(
         @Autowired cityService: CityService,
-    ): Consumer = Consumer(
-        cityService = cityService,
-    )
+    ): Consumer = Consumer(cityService)
 
     @Bean
     fun consumerFactory(): ConsumerFactory<String, String> {
         val configs = mapOf(
-            ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG to servers,
-            ConsumerConfig.GROUP_ID_CONFIG to consumerGroup,
+            ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG to kafkaProperties.bootstrapServers,
+            ConsumerConfig.GROUP_ID_CONFIG to kafkaProperties.consumer.groupId,
             ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG to StringDeserializer::class.java,
             ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG to StringDeserializer::class.java,
         )

src/main/kotlin/com/example/demo/config/KafkaProducerConfig.kt

@@ -2,10 +2,10 @@ package com.example.demo.config
 
 import com.example.demo.services.kafka.Producer
 import com.example.demo.services.kafka.ProducerImpl
+import com.example.demo.services.kafka.SchemaValidator
 import org.apache.kafka.clients.producer.ProducerConfig
 import org.apache.kafka.common.serialization.StringSerializer
 import org.springframework.beans.factory.annotation.Autowired
-import org.springframework.beans.factory.annotation.Value
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
 import org.springframework.kafka.core.DefaultKafkaProducerFactory
@@ -14,14 +14,13 @@ import org.springframework.kafka.core.ProducerFactory
 
 @Configuration
 class KafkaProducerConfig(
-    @Value("\${kafka.bootstrap-servers}")
-    val servers: String
+    @Autowired val kafkaProperties: KafkaProperties
 ) {
     @Bean
     fun producerFactory(): ProducerFactory<String, Any> {
         val configProps: MutableMap<String, Any> = HashMap()
 
-        configProps[ProducerConfig.BOOTSTRAP_SERVERS_CONFIG] = servers
+        configProps[ProducerConfig.BOOTSTRAP_SERVERS_CONFIG] = kafkaProperties.bootstrapServers
         configProps[ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG] = StringSerializer::class.java
         configProps[ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG] = StringSerializer::class.java
 
@@ -36,7 +35,9 @@ class KafkaProducerConfig(
     @Bean
     fun producer(
         @Autowired kafkaTemplate: KafkaTemplate<String, Any>,
+        @Autowired schemaValidator: SchemaValidator,
     ): Producer = ProducerImpl(
         kafkaTemplate,
+        schemaValidator,
     )
 }

src/main/kotlin/com/example/demo/config/KafkaProperties.kt

@@ -0,0 +1,30 @@
+package com.example.demo.config
+
+import org.springframework.boot.context.properties.ConfigurationProperties
+import org.springframework.boot.context.properties.bind.ConstructorBinding
+
+@ConfigurationProperties("kafka")
+data class KafkaProperties @ConstructorBinding constructor(
+    val bootstrapServers: String,
+    val producer: Producer,
+    val consumer: Consumer,
+    val validation: Validation,
+) {
+    data class Producer(
+        val product: Product,
+    ) {
+        data class Product(
+            val defaultSyncTopic: String
+        )
+    }
+
+    data class Consumer(
+        val groupId: String,
+        val topics: String,
+        val autoStartup: Boolean,
+    )
+
+    data class Validation(
+        val schema: Map<String, String>
+    )
+}

src/main/kotlin/com/example/demo/services/kafka/ProducerImpl.kt

@@ -13,10 +13,14 @@ import org.springframework.stereotype.Service
 @Service
 class ProducerImpl(
     private val kafkaTemplate: KafkaTemplate<String, Any>,
+    private val schemaValidator: SchemaValidator,
 ): Producer {
     override fun produceProductInfo(topicName: String, product: Product) {
 
         val serializedProduct = Json.encodeToJsonElement(ProductDto(product))
+
+        schemaValidator.validate("product-sync", serializedProduct)
+
         val message: Message<String> = MessageBuilder
             .withPayload(serializedProduct.toString())
             .setHeader(KafkaHeaders.TOPIC, topicName)

src/main/kotlin/com/example/demo/services/kafka/SchemaValidator.kt

@@ -0,0 +1,46 @@
+package com.example.demo.services.kafka
+
+import io.github.optimumcode.json.schema.JsonSchema
+import io.github.optimumcode.json.schema.ValidationError
+import kotlinx.serialization.json.JsonElement
+import org.springframework.util.ResourceUtils
+
+class SchemaValidator(
+    private val schemaMap: Map<String, String>,
+) {
+    private val loadedSchema: MutableMap<String, String> = mutableMapOf()
+
+    fun validate(schemaName: String, value: JsonElement) {
+
+        val schema = JsonSchema.fromDefinition(
+            getSchema(schemaName),
+        )
+
+        val errors = mutableListOf<ValidationError>()
+
+        val valid = schema.validate(value, errors::add)
+        if (!valid) {
+            // todo throw another exception
+            println(errors.toString())
+
+           throw RuntimeException("invalid schema")
+        }
+    }
+
+    private fun getSchema(schemaName: String): String {
+        val loaded = loadedSchema[schemaName]
+        if (loaded != null) {
+            return loaded
+        }
+
+        val schemaFile = schemaMap[schemaName]
+            ?: // todo throw another exception
+            throw RuntimeException("unknown json-schema")
+
+        val schema = ResourceUtils.getFile("classpath:json-schemas/$schemaFile")
+            .readText(Charsets.UTF_8)
+        loadedSchema[schemaName] = schema
+
+        return schema
+    }
+}