如何在 Spring Boot Docker 中连接到 MongoDB Atlas？

Question

I would like to deploy a Spring Boot application to Docker, but it is unable to connect to my database set up in MongoDB Atlas. The app starts up fine, but connection to the repository is refused when I attempt to run docker-compose up .

The exception:

app-server_1  | 2021-07-27 18:56:54.599  INFO 1 --- [           main] org.mongodb.driver.cluster               : Cluster created with settings {hosts=[localhost:27017], mode=SINGLE, requiredClusterType=UNKNOWN, serverSelectionTimeout='30000 ms'}
app-server_1  | 2021-07-27 18:56:54.817  INFO 1 --- [localhost:27017] org.mongodb.driver.cluster               : Exception in monitor thread while connecting to server localhost:27017
app-server_1  |
app-server_1  | com.mongodb.MongoSocketOpenException: Exception opening socket
app-server_1  |         at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:70) ~[mongodb-driver-core-4.1.2.jar!/:na]
app-server_1  |         at com.mongodb.internal.connection.InternalStreamConnection.open(InternalStreamConnection.java:143) ~[mongodb-driver-core-4.1.2.jar!/:na]
app-server_1  |         at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.lookupServerDescription(DefaultServerMonitor.java:188) ~[mongodb-driver-core-4.1.2.jar!/:na]
app-server_1  |         at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:144) ~[mongodb-driver-core-4.1.2.jar!/:na]
app-server_1  |         at java.lang.Thread.run(Thread.java:748) [na:1.8.0_292]
app-server_1  | Caused by: java.net.ConnectException: Connection refused (Connection refused)
app-server_1  |         at java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:1.8.0_292]
app-server_1  |         at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_292]
app-server_1  |         at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_292]
app-server_1  |         at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_292]
app-server_1  |         at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_292]
app-server_1  |         at java.net.Socket.connect(Socket.java:607) ~[na:1.8.0_292]
app-server_1  |         at com.mongodb.internal.connection.SocketStreamHelper.initialize(SocketStreamHelper.java:78) ~[mongodb-driver-core-4.1.2.jar!/:na]
app-server_1  |         at com.mongodb.internal.connection.SocketStream.initializeSocket(SocketStream.java:79) ~[mongodb-driver-core-4.1.2.jar!/:na]
app-server_1  |         at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:65) ~[mongodb-driver-core-4.1.2.jar!/:na]
app-server_1  |         ... 4 common frames omitted

application.properties:

spring.datasource.url = mongodb+srv://admin:myPassword@cluster0.gf9zs.mongodb.net/my-app?retryWrites=true&w=majority
spring.data.mongodb.authentication-database=admin
spring.data.mongodb.database=my-app

docker-compose.yml - I think that the mongo service specified here is like running a separate database rather than connecting remotely like in application.properties. I would prefer to connect to Atlas since it is inexpensive. For now, I left mongo as an orphan service.

version: '3.7'
services:
  mongo:
    container_name: mongodb
    image: mongo
    volumes:
      - ./database:/data
    ports:
      - "27017:27017"

  # App backend service
  app-server:
    build:
      context: my-app-spring
      dockerfile: Dockerfile
    ports:
      - "8080:8080"
    restart: always
    depends_on: 
      - mongo # This service depends on MongoDB. Start that first.
    

Dockerfile

FROM scratch
FROM openjdk:8
RUN mvn install
EXPOSE 8080
ADD target/my-app.jar my-app.jar 
ENTRYPOINT ["java","-jar","/my-app.jar"]

What I have tried

• Setting IP access to everywhere from the Atlas dashboard
• Adding the username and password to separate Spring Boot properties
• Running the app outside of Docker. This works, but only if I have MongoDB Service running. Maybe Docker needs its own MongoDB Service inside the container in order to connect to the database, which is outside the container.
• Following this guide: https://developer.mongodb.com/how-to/use-atlas-on-heroku/ . The goal is ultimately to deploy the Docker container to Heroku.
• Looking at other SO questions. Usually, the OP had mistakenly written "localhost" somewhere.
• Checking my Firewall access

Question: How can I resolve this exception? What are some probable causes of it?

Answer 1

I figured it out, but I'm not using Atlas just yet. The problem was that I needed the mymongodb container name to match the spring.data.mongodb.host property in application.properties. When docker-compose up didn't work, I built the images separately then tested them. These are the troubleshooting commands I ran:

docker pull mongo:latest
docker run -d -p 27017:27017 --name mymongodb mongo:latest
docker build -t springboot-mongodb:1.0 . #you need to run mvn clean install and be in the directory of the Dockerfile in order for this to work
docker run -p 8080:8080 --name springboot-mongodb --link mymongodb:mongo -d springboot-mongodb:1.0

These commands prepare MongoDB and Spring Boot images then run them as linked containers. If these commands work, then you should be able to reach your API with Postman then proceed to write a docker-compose.yml file such as the one below.

Here are the working files:

application.properties:

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

docker-compose.yml:

version: "3"
services:
 mymongodb:
   image: mongo:latest
   container_name: "mymongodb"
   ports:
     - 27017:27017
 springboot-mongodb:
   build:
     context: my-app-spring
     dockerfile: Dockerfile
   container_name: springboot-mongodb
   ports:
     - 8080:8080
   links:
     - mymongodb 

Dockerfile:

FROM adoptopenjdk/openjdk11:alpine-jre
ADD target/my-app.jar app.jar
ENTRYPOINT ["java","-jar","app.jar"]