Spring boot docker Cannot connect to mysql (Connection refused / createCommunicationsException)

Question

Alright so i have spring-boot java application, mysql db and nginx. I start them and it looks like this (command i use is docker-compose up that is all i need to execute):

The Error that i have in my application workaround_app_1 is following:

     /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.4.RELEASE)

14:46:59.083 INFO [c.b.w.WorkaroundApplication]  Starting WorkaroundApplication on 9b42d0d4614b with PID 48 (/app/target/classes started by root in /app)
14:46:59.089 INFO [c.b.w.WorkaroundApplication]  The following profiles are active: devdock
14:47:11.985 INFO [o.a.c.h.Http11NioProtocol]  Initializing ProtocolHandler ["https-jsse-nio-8080"]
14:47:12.015 INFO [o.a.c.c.StandardService]  Starting service [Tomcat]
14:47:12.016 INFO [o.a.c.c.StandardEngine]  Starting Servlet engine: [Apache Tomcat/9.0.17]
14:47:13.993 INFO [o.a.c.c.C.[.[.[/workaround]]  Initializing Spring embedded WebApplicationContext
14:47:13.996 INFO [o.s.w.c.ContextLoader]  Root WebApplicationContext: initialization completed in 14635 ms
14:47:17.906 INFO [c.z.h.HikariDataSource]  HikariPool-1 - Starting...
14:47:19.294 ERROR [c.z.h.p.HikariPool]  HikariPool-1 - Exception during pool initialization.
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
        at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)
        at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
        at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:835)
        at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:455)
        at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240)
        at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199)
        at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:136)
        at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:369)
        at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:198)
        at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:467)
        at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:541)
        at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115)
        at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112)
        at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:157)
        at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:115)
        at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:78)
        at org.springframework.jdbc.support.JdbcUtils.extractDatabaseMetaData(JdbcUtils.java:319)
        at org.springframework.jdbc.support.JdbcUtils.extractDatabaseMetaData(JdbcUtils.java:356)
        at org.springframework.boot.autoconfigure.orm.jpa.DatabaseLookup.getDatabase(DatabaseLookup.java:73)
        at org.springframework.boot.autoconfigure.orm.jpa.JpaProperties.determineDatabase(JpaProperties.java:142)
        at org.springframework.boot.autoconfigure.orm.jpa.JpaBaseConfiguration.jpaVendorAdapter(JpaBaseConfiguration.java:113)
        at org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaConfiguration$$EnhancerBySpringCGLIB$$aadd42f9.CGLIB$jpaVendorAdapter$4(<generated>)
        at org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaConfiguration$$EnhancerBySpringCGLIB$$aadd42f9$$FastClassBySpringCGLIB$$962bc1e0.invoke(<generated>)
        at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244)
        at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(Configuratio

That goes on and one till at the end you see

    The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
        at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
        at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:91)
        at com.mysql.cj.NativeSession.connect(NativeSession.java:152)
        at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:955)
        at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:825)
        ... 188 common frames omitted
Caused by: java.net.ConnectException: Connection refused (Connection refused)
        at java.base/java.net.PlainSocketImpl.socketConnect(Native Method)
        at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399)
        at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242)
        at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224)
        at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:403)
        at java.base/java.net.Socket.connect(Socket.java:591)
        at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:155)
        at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:65)
        ... 191 common frames omitted

This is my docker-compose:

version: '3'
services:
  nginx:
   container_name: some-nginx
   image: nginx:1.13
   restart: always
   ports:
   - 8080:8080
   volumes:
   - ./nginx/conf.d:/etc/nginx/conf.d
   depends_on:
   - app

  mysql:
   container_name: workaround-mysql
   image: mysql/mysql-server:5.7
   environment:
    MYSQL_DATABASE: workaround
    MYSQL_USER: springuser
    MYSQL_PASSWORD: admin
    MYSQL_ROOT_PASSWORD: admin
    MYSQL_ROOT_HOST: '%'
   ports:
   - "3308:3306"
   restart: always

  app:
    restart: always
    build: ./
    working_dir: /app
    volumes:
      - ./:/app
      - ~/.m2:/root/.m2
    expose:
      - "8080"
    command: mvn clean spring-boot:run
    depends_on:
      - mysql

And here is my application.properties:

###################################
#---------DATABASE
###################################
#
# URL for the mysql db
spring.datasource.url=jdbc:mysql://workaround-mysql:3308/workaround?serverTimezone=UTC&max_allowed_packet=15728640
# User name in mysql
spring.datasource.username=springuser
# Password for mysql
spring.datasource.password=admin

My Dockerfile only contains one liner: FROM openjdk:12-jdk

All of that in mind, What is happening why i cannot connect to my database? When i do it out of docker, all works fine on localhost. Bud cant get it working with this setup. Could that be that somehow my workaround_app_1 started sooner then mysql and now cant function? Bud in my docker-compose I specified that it depends on mysql to be started right ?Im new to docker + nginx.

Notes:

I have tried different ports for mysql bud that doesnt seem to be issue. I also dont think its issue with resources or anything related so hardware constraints. Are my configurations proper ? Btw i use Docker for windows, 64bit machine jdk12. I have tried some demo applications and they were working fine.

Answer 1

The ports mapping in your docker-compose.yml is only relevant for the host, so you'll be able to connect to your DB through localhost:3308 . But inside your other docker-compose containers (that is, the compose default network), you'd have to use workaround-mysql:3306 .

Answer 2

You can connect from host to db in docker container, but you cannot connect to db in docker container from other docker container.

Check mysql settings and allow connections from app container's IP (or docker network).

Answer 3

Ok so the issue was , mysql got stuck on :

[Entrypoint] Starting MySQL 5.7.26-1.1.11

Nothing could connect to it. Application that needed it was starting up and it could not connect so it was throwing errors.

Here is another question of mayne regarding this issue and you can see its solved : Docker MySQL - can't connect from Spring Boot app to MySQL database