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):
[![enter image description here](https://i.stack.imgur.com/r9XoO.png)](https://i.stack.imgur.com/r9XoO.png)

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.