带有嵌入式Mongo的Spring Boot：无法分配请求的地址:JVM_Bind

Question

我正在尝试为嵌入Mongo&Kafka的Spring Boot设置一个JUnit测试：-

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE,
        classes = {AccountingApplication.class})
@DataMongoTest
public class BaseEmbeddedTest {


    @ClassRule
    public static KafkaEmbedded embeddedKafka = new KafkaEmbedded(1, true);

    @Autowired
    private MongoTemplate mongoTemplate;


    @Test
    public void emptyTest(){

    }

}

src/test/resources/application.yml：-

spring:
  data:
    mongodb:
      port: 0
  kafka:
    bootstrap-servers: ${spring.embedded.kafka.brokers}

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [de.flapdoodle.embed.mongo.config.IMongodConfig]: Factory method 'embeddedMongoConfiguration' threw exception; nested exception is java.net.BindException: Cannot assign requested address: JVM_Bind
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588)
    ... 140 more
Caused by: java.net.BindException: Cannot assign requested address: JVM_Bind
    at java.net.DualStackPlainSocketImpl.bind0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketBind(DualStackPlainSocketImpl.java:106)
    at java.net.AbstractPlainSocketImpl.bind(AbstractPlainSocketImpl.java:387)
    at java.net.PlainSocketImpl.bind(PlainSocketImpl.java:190)
    at java.net.ServerSocket.bind(ServerSocket.java:375)
    at java.net.ServerSocket.<init>(ServerSocket.java:237)
    at de.flapdoodle.embed.process.runtime.Network.getFreeServerPort(Network.java:80)
    at org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration.embeddedMongoConfiguration(EmbeddedMongoAutoConfiguration.java:147)

版本：-

    dependencyManagementPluginVersion = '1.0.3.RELEASE'
    springBootVersion = '1.5.6.RELEASE'
    springCloudVersion = 'Dalston.SR2'
    projectVersion = '0.0.1-SNAPSHOT'
    javaVersion = 1.8
    kotlinVersion = '1.1.4'

Answer 1

以下注释:@datamongotest导致Spring Boot创建一个嵌入式Mongo实例。异常消息告诉我们，嵌入的Mongo实例无法启动，因为它试图运行的端口上已经有一个进程在运行。

嵌入式Mongo实例由EmbeddedMongoAutoConfiguration配置，Spring Boot应用的策略--端口分配--如下所示：

if configured Mongo port > 0 then 
    use the configured port
else 
    assign a random port
end

因此，我怀疑您的测试上下文为spring.data.mongodb.port配置了一个非零值。我知道您发布了application.yml，这意味着您正确地为spring.data.mongodb.port分配了一个零值，但是如果您在EmbeddedMongoAutoConfiguration构造函数中放置一个断点，并在properties参数中查看，我想您会看到该配置类使用的实际值不是零。如果传递给EmbeddedMongoAutoConfiguration的端口值实际上为零，但仍然得到JVM_Bind错误，那么这意味着这个调用:network.getFreeServerPort(this.getHost())没有返回空闲端口，这似乎不太可能。

为了解决这个问题：只要您用Spring.data.mongodb.port=0配置测试上下文，那么嵌入的Mongo实例将被分配一个随机端口，并且这个随机端口将被Spring上下文的其他方面（例如MongoTemplate)所知道，这些方面需要与Mongo实例对话。