Connection Refused : While Running the Docker Compose

Question

I am new baby to the Docker. I am using docker within the spring boot application. Below is my file .

Application.properties file:

spring.datasource.url=jdbc:mysql://${DATABASE_HOST}:3306/${DATABASE_NAME}?allowPublicKeyRetrieval=true&useSSL=true
spring.datasource.username = root
spring.datasource.password = root
server.port=8443

DockerFile:

FROM openjdk:latest
ADD target/app.jar app.jar
EXPOSE 8443
ENTRYPOINT ["java","-jar","app.jar", "--spring.profiles.active=docker"]

Docker Compose :

version: '3.1'
services:
  mysqlDb:
    image: mysql:latest
    environment:
      - MYSQL_ROOT_PASSWORD=root
      - MYSQL_DATABASE=springdemo
      - MYSQL_USER=root
      - MYSQL_PASSWORD=root
      - DATABASE_HOST= 192.168.0.1
    volumes:
      - /data/mysql
    ports:
    - "3306:3306"
    container_name: mysql-db

  springbootdocker:
    image: xyz/signup
    restart: always
    ports:
      - "8080:8080"
    depends_on:
      - mysqlDb
    links:
      - mysqlDb   
    environment:
      - DATABASE_HOST= mysqlDb
      - DATABASE_USER=root
      - DATABASE_PASSWORD=root
      - DATABASE_NAME=springdemo
      - DATABASE_PORT=3306
    healthcheck:
      test: ["CMD","curl","-f","http://localhost:8080/health"]
      interval: 1m30s
      timeout: 10s 
      retries: 3

1st part of Issue is Resolved : when i run the App , i get the following error :

Caused by: com.mysql.cj.exceptions.CJCommunicationsException: 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.



Caused by: java.net.UnknownHostException: ${DATABASE_HOST}

1) What i am trying to Achieve -

Want to create a jar for my application.
After creating a jar , i want to create the image from the jar
After creating the image of the application , i want to push into the docker hub .
From other server , I will run docker-compose.yml file . It will fetch the mysql and image from the docker hub and run the application in the other port as mentioned in the docker-compose.

Hope I am clear ,what i want to acheive .

Here comes the problem :

when i am trying to run the application locally , i am able to create the jar only when ,i write this line in application.properties class.

spring.datasource.url=jdbc:mysql://127.0.0.1:3306/springdemo?allowPublicKeyRetrieval=true&useSSL=true

I am able to create the jar and after that image to -> upload that image to docker hub , when i am running the docker-compose able to pull that image but can't able to connect to the mysql workbench.

So,I thought, I am running the docker-compose in diffrent System/Server. There ip address is different.

So, I changed the url to this :

spring.datasource.url=jdbc:mysql://192.168.0.1:3306/springdemo?allowPublicKeyRetrieval=true&useSSL=true

where

192.168.0.1 - this ip is for the diffrent server, where i want to run the docker-compose file

But when i am running the spring boot application , I am unable to run the application because it's saying the almost the same error as mentioned above i.e Connection refuse . So i am unable to create the jar so , unable to create the image . So my idea fails here also.

Then Again, One idea again come into my mind , can't we put the dynamic ip address in application.properties file,so i tried this line :

spring.datasource.url=jdbc:mysql://${DATABASE_HOST}:3306/${DATABASE_NAME}?allowPublicKeyRetrieval=true&useSSL=true

DATABASE_HOST- you can find it in docker-compose file

I thought may be this one : ${DATABASE_HOST} , will pick the value of the DATABASE_HOST from the docker-compose .

But my idea failed , I am getting the error as mentioned in top while running the application. can't able to create jar ,so unable to create the image .

2nd Part - Issue is still Open

when i am able to run the docker-compose in my local terminal , and able to create the container . I can also see mysql is connected as well as my schema . But when i am trying to access my API using postman or web browser then , it's saying not connected

http://localhost:8080/dockerex

Inside my Controller Class:

@RestController
@RequestMapping(value = "/dockerex")
public class SpringBootDockerController {

    @GetMapping
    public String check() {
        return "checking";
    }
}

when i inspect my container , ip address is coming blank : snapshot of conatiner :

[
 {
     "Id": "7664bab5ed452e3e2243e1802010240ab5a3eb817af6164e985b10e729ff4c8f",
     "Created": "2020-02-04T17:30:08.5351511Z",
     "Path": "java",
     "Args": [
         "-jar",
         "app.jar",
         "--spring.profiles.active=docker"
     ],
     "State": {
         "Status": "running"
.......................
"PortBindings": {
             "8080/tcp": [
                 {
                     "HostIp": "",
                     "HostPort": "8080"
                 }
             ]
         },

Vishal Vishwakarma Vishal Vishwakarma · Accepted Answer · 2020-02-04T08:32:49

Good it worked but here you see you were using DB_HOST earlier, now you are using DATABASE_HOST= mysqlDb , which is currently pointing to your mysql service name. this service name can be discovered within the single network created by docker compose. You were hardcoding DB_HOST=192.168.0.1 and trying to connect using this IP , which is invalid as docker compose create its network.

Connection Refused : While Running the Docker Compose

4 Answers