com.mongodb.MongoSocketOpenException: Exception opening socket

could you help me .I try to deploy application on ubuntu server.I use docker-compose up.I have this error.

com.mongodb.MongoSocketOpenException: Exception opening socket
spring-mongo    |       at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:70) ~[mongodb-driver-core-4.0.5.jar!/:na]
spring-mongo    |       at com.mongodb.internal.connection.InternalStreamConnection.open(InternalStreamConnection.java:127) ~[mongodb-driver-core-4.0.5.jar!/:na]
spring-mongo    |       at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:117) ~[mongodb-driver-core-4.0.5.jar!/:na]
spring-mongo    |       at java.lang.Thread.run(Thread.java:748) [na:1.8.0_212]
spring-mongo    | Caused by: java.net.ConnectException: Connection refused (Connection refused)
spring-mongo    |       at java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:1.8.0_212]
spring-mongo    |       at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_212]
spring-mongo    |       at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_212]
spring-mongo    |       at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_212]
spring-mongo    |       at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_212]
spring-mongo    |       at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_212]
spring-mongo    |       at com.mongodb.internal.connection.SocketStreamHelper.initialize(SocketStreamHelper.java:63) ~[mongodb-driver-core-4.0.5.jar!/:na]
spring-mongo    |       at com.mongodb.internal.connection.SocketStream.initializeSocket(SocketStream.java:79) ~[mongodb-driver-core-4.0.5.jar!/:na]
spring-mongo    |       at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:65) ~[mongodb-driver-core-4.0.5.jar!/:na]
spring-mongo    |       ... 3 common frames omitted

Dokerfile

FROM openjdk:8-jdk-alpine
ADD target/spring-mongo.jar spring-mongo.jar
ENTRYPOINT ["java","-jar","spring-mongo.jar"]

application.properties

spring.data.mongodb.host=mymongodb
spring.data.mongodb.port=27017
spring.data.mongodb.database=mongo
spring.data.mongodb.repositories.enabled=true

docer-compose.yml

version: "3"
services:
  mymongodb:
    image: mongo:latest
    container_name: "mymongodb"
    ports:
      - 27017:27017
  spring-mongo:
    image: spring-mongo:1.0
    container_name: spring-mongo
    ports:
      - 8080:8080
    links:
      - mymongodb

In your docker-compose.yml, you are only linking your spring boot application with your mongodb.

In your application.properties, you are using mongodb which is not a valid host.

You need to pass the environment variables for your spring application. For it, you can do something like this in your docker-compose.yml.

version: "3"
services:
  mymongodb:
    image: mongo:latest
    container_name: "mymongodb"
    ports:
      - 27017:27017
  spring-mongo:
    image: spring-mongo:1.0
    container_name: spring-mongo
    ports:
      - 8080:8080
    environment:
      - MONGO_HOST=mymongodb
    links:
      - mymongodb

And in your application.properties,

spring.data.mongodb.host=${MONGO_HOST}

Try depends_on instead of links,
it worked for me.

version: "3"
services:
  mymongodb:
    image: mongo:latest
    container_name: "mymongodb"
    network_mode: host
    restart: always
    ports:
     - 27017:27017
  spring-mongo:
    image: spring-mongo:1.0
    container_name: spring-mongo
    network_mode: host
    restart: always
    ports:
     - 8080:8080
    depends_on:
     - mymongodb

With the below docker-compose.yml and application.properties configuration its working for me.
docker-compose.yml
docker-compose.yml

# Use root/example as user/password credentials
version: '3.1'

services:

  mongo:
    image: mongo:4.4.5
    restart: always
    ports:
      - 27017:27017
    environment:
      MONGO_INITDB_ROOT_USERNAME: root
      MONGO_INITDB_ROOT_PASSWORD: example

  mongo-express:
    image: mongo-express
    restart: always
    ports:
      - 8081:8081
    environment:
      ME_CONFIG_MONGODB_ADMINUSERNAME: root
      ME_CONFIG_MONGODB_ADMINPASSWORD: example
      ME_CONFIG_MONGODB_URL: mongodb://root:example@mongo:27017/

application.properties

spring.data.mongodb.authentication-database=admin
spring.data.mongodb.username=root
spring.data.mongodb.password=example
spring.data.mongodb.database=springAppDB
spring.data.mongodb.port=27017
spring.data.mongodb.host=localhost