Mongodb connection error though docker in springboot - mongodb

Question

I am learning docker and trying to create a docker-compose.yml file for a springboot db application(jdk 10). Spring boot picks up 27017 as a default port for mongodb, so if I start a mongo container with below command:
docker run -d -p 27017:27017 mongo
And then start my application in intellij, everything works fine. When I try to use a docker-compose.yml, i get a connection exception.
This is my Dockerfile
FROM openjdk:8-jdk-alpine
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} app.jar
ENTRYPOINT ["java","-jar","/app.jar"]
This is my docker-compose.yml:
services:
java:
image: adoptopenjdk/openjdk10:latest
mongo:
image: mongo
expose:
- "27017"
ports:
- "0.0.0.0:27017:27017"
spring_boot_mongo:
build: .
ports:
- "8080:8080"
links:
- java
version: "2"
Error while running docker-compose up command:
localhost:27017
spring_boot_mongo_1 |
spring_boot_mongo_1 | com.mongodb.MongoSocketOpenException: Exception opening socket
spring_boot_mongo_1 | at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:67) ~[mongodb-driver-core-3.8.2.jar!/:na]
spring_boot_mongo_1 | at com.mongodb.internal.connection.InternalStreamConnection.open(InternalStreamConnection.java:126) ~[mongodb-driver-core-3.8.2.jar!/:na]
spring_boot_mongo_1 | at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:117) ~[mongodb-driver-core-3.8.2.jar!/:na]
spring_boot_mongo_1 | at java.lang.Thread.run(Thread.java:748) [na:1.8.0_212]
spring_boot_mongo_1 | Caused by: java.net.ConnectException: Connection refused (Connection refused)
spring_boot_mongo_1 | at java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:1.8.0_212]
spring_boot_mongo_1 | at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_212]
spring_boot_mongo_1 | at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_212]
spring_boot_mongo_1 | at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_212]
spring_boot_mongo_1 | at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_212]
spring_boot_mongo_1 | at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_212]
spring_boot_mongo_1 | at com.mongodb.internal.connection.SocketStreamHelper.initialize(SocketStreamHelper.java:64) ~[mongodb-driver-core-3.8.2.jar!/:na]
spring_boot_mongo_1 | at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:62) ~[mongodb-driver-core-3.8.2.jar!/:na]
spring_boot_mongo_1 | ... 3 common frames omitted
spring_boot_mongo_1 |
This is what I see when i run docker ps:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4da4948d04d9 spring-boot-mongodb-master_spring_boot_mongo "java -jar /app.jar" 11 seconds ago Up 10 seconds 0.0.0.0:8080->8080/tcp spring-boot-mongodb-master_spring_boot_mongo_1
e9a79f3ba8ab mongo "docker-entrypoint.s…" 12 seconds ago Up 10 seconds 0.0.0.0:27017->27017/tcp spring-boot-mongodb-master_mongo_1
This means the mongo mapping works as expected(I see the same o/p when i start mongodb container with the above mentioned docker run command), but the application port mapping was not achieved. Can someone please help me??
Thanks!

Answer 1

Services from the same docker-compose are connected to same default network. You should use service name in your url when you want to access another container. Container name will be resolved to container IP automatically. You cannot access another container by using localhost - use service name instead. In your case you can set environment variable for your spring_boot_mongo service :
spring_boot_mongo:
build: .
ports:
- "8080:8080"
environment:
- SPRING_DATA_MONGODB_.HOST=mongo
if you are using spring data mongo. Otherwise set the environment variable to override your uri in your application container.