SpringBoot Spring data properties for Mongo causes exception even when programmatically configured

Hello,

I am using the reactive spring data mongodb starter: implementation 'org.springframework.boot:spring-boot-starter-data-mongodb-reactive'"

Instead of using the spring data properties to configure Mongo if I create a configuration file like the below I can connect and use the mongodb successfully, BUT receive the exception below. However, when I add the spring mongodb properties, the exception does not occur, but everything still works. Shouldn't the configuration override spring.properties or vice versa? or at least an error should not be caused.

#mongo
spring.data.mongodb.database=my_db
spring.data.mongodb.uri=mongodb+srv://username:password@xxxx.net
spring.data.mongodb.repositories.enabled=true

com.mongodb.MongoSocketOpenException: Exception opening socket
        at com.mongodb.connection.netty.NettyStream$OpenChannelFutureListener.operationComplete(NettyStream.java:439) ~[mongodb-driver-core-4.1.2.jar:na]
        at com.mongodb.connection.netty.NettyStream$OpenChannelFutureListener.operationComplete(NettyStream.java:407) ~[mongodb-driver-core-4.1.2.jar:na]
        at io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:578) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.concurrent.DefaultPromise.notifyListeners0(DefaultPromise.java:571) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.concurrent.DefaultPromise.notifyListenersNow(DefaultPromise.java:550) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:491) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.concurrent.DefaultPromise.setValue0(DefaultPromise.java:616) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.concurrent.DefaultPromise.setFailure0(DefaultPromise.java:609) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.concurrent.DefaultPromise.tryFailure(DefaultPromise.java:117) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.fulfillConnectPromise(AbstractNioChannel.java:321) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:337) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:707) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:655) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:581) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]
Caused by: io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: no further information: localhost/[0:0:0:0:0:0:0:1]:27017
Caused by: java.net.ConnectException: Connection refused: no further information
        at java.base/sun.nio.ch.Net.pollConnect(Native Method) ~[na:na]
        at java.base/sun.nio.ch.Net.pollConnectNow(Net.java:589) ~[na:na]
        at java.base/sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:839) ~[na:na]
        at io.netty.channel.socket.nio.NioSocketChannel.doFinishConnect(NioSocketChannel.java:330) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:334) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:707) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:655) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:581) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
        at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]

Working configuration

@Configuration
@EnableReactiveMongoAuditing
@EnableReactiveMongoRepositories(basePackages = {"xxx.xxx.repository"})
class MongoDbConfiguration {

    private static final Logger LOGGER = LoggerFactory.getLogger(MongoDbConfiguration.class);

    @Bean
    public ReactiveMongoDatabaseFactory reactiveMongoDatabaseFactory() {

        MongoClient mongoClient = MongoClients.create("mongodb+srv://username:password@xxxx.com");

        return new SimpleReactiveMongoDatabaseFactory(mongoClient, "my_database");

    }

    @Bean
    public ReactiveMongoTemplate reactiveMongoTemplate() {
        ReactiveMongoTemplate template = new ReactiveMongoTemplate(reactiveMongoDatabaseFactory());
        template.setWriteResultChecking(WriteResultChecking.EXCEPTION);

        return template;
    }

}

Comment From: odrotbohm

Transferred to the Boot tracker per @christophstrobl's request.

Comment From: wilkinsona

MongoReactiveAutoConfiguration creates a com.mongodb.reactivestreams.client.MongoClient if no other bean of that type has already been defined. While you are creating your own MongoClient, you haven't defined it as a bean so the auto-configured client is still created. In the absence of any spring.data.mongodb.* properties, it'll use the default configuration and try to connect to localhost:27017.

I would recommend defining your own MongoClient bean. Alternatively, you could disable the auto-configuration.