Spring-boot application in docker container is unable to connect to mongodb docker container

Question

When I trying to run my spring-boot application on docker, it is not able to connect to the Mongodb container running in docker.

Application.properties

spring.data.mongodb.port=27017
spring.data.mongodb.host=localhost

Dockerfile for spring application

FROM openjdk
COPY target/*.jar app.jar
ENTRYPOINT ["java","-jar","/app.jar"]

docker-compose.yaml

version: '3'
services:
  mongo:
    image: mongo:latest
    container_name: docker-mongo
    ports:
      - "27017:27017"
  wacaj_docker:
    image: wacaj
    depends_on:
      - mongo
    container_name: wacaj
    build: .
    ports:
      - "8080:8080"

I am able to connect to the mongodb container from my local system, but the spring-application container is not able to connect to mongo container. And also if I run the spring application in local it is able to connect to the mongo runneing in docker container. I am unable to troubleshoot the problem.

I tried changing hostname to both servicename ie mongo and container name ie docker-mongo, but it is still not working.

2023-01-07 08:50:03.146  INFO 1 --- [localhost:27017] org.mongodb.driver.cluster               : Exception in monitor thread while connecting to server localhost:27017
wacaj         | 
wacaj         | com.mongodb.MongoSocketOpenException: Exception opening socket
wacaj         |         at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:70) ~[mongodb-driver-core-4.6.1.jar!/:na]
wacaj         |         at com.mongodb.internal.connection.InternalStreamConnection.open(InternalStreamConnection.java:180) ~[mongodb-driver-core-4.6.1.jar!/:na]
wacaj         |         at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.lookupServerDescription(DefaultServerMonitor.java:193) ~[mongodb-driver-core-4.6.1.jar!/:na]
wacaj         |         at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:157) ~[mongodb-driver-core-4.6.1.jar!/:na]
wacaj         |         at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]
wacaj         | Caused by: java.net.ConnectException: Connection refused
wacaj         |         at java.base/sun.nio.ch.Net.pollConnect(Native Method) ~[na:na]
wacaj         |         at java.base/sun.nio.ch.Net.pollConnectNow(Net.java:672) ~[na:na]
wacaj         |         at java.base/sun.nio.ch.NioSocketImpl.timedFinishConnect(NioSocketImpl.java:539) ~[na:na]
wacaj         |         at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:594) ~[na:na]
wacaj         |         at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:327) ~[na:na]
wacaj         |         at java.base/java.net.Socket.connect(Socket.java:633) ~[na:na]
wacaj         |         at com.mongodb.internal.connection.SocketStreamHelper.initialize(SocketStreamHelper.java:107) ~[mongodb-driver-core-4.6.1.jar!/:na]
wacaj         |         at com.mongodb.internal.connection.SocketStream.initializeSocket(SocketStream.java:79) ~[mongodb-driver-core-4.6.1.jar!/:na]
wacaj         |         at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:65) ~[mongodb-driver-core-4.6.1.jar!/:na]

Answer 1

You need to change the hostname:

spring.data.mongodb.host=mongo

Docker makes every service in a docker compose setup available under its service name, in your case mongo and wacaj_docker .

Please refer to the docs for further details.