Deploying Multiple Spring Boot Microservices to Docker

In a previous docker tutorial we saw how to deploy a single Spring Boot Microservice to Docker Container. But suppose the requirement is such that we may need to deploy multiple microservices to Docker Container. For example we have the following microservices that we have defined in previous tutorial.

As the name suggests employee-producer will be exposing REST APIs which will be consumed by the employee-consumer.

The way Docker has been designed such that a Docker Container should have only a single service running. Again we can have multiple services running in docker using some workarounds but this will not be a good design. So we will be deploying the two microservices employee-producer and employee-consumer to two different containers and then have them interact with each other.

In order to achieve this will have to make use of the docker networking commands.

This tutorial is explained in the below Youtube Video.

Lets Begin!

Lets begin with the implementation part. Import the two projects in eclipse.

• Employee Producer

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From openjdk:8

copy ./target/employee-producer-0.0.1-SNAPSHOT.jar employee-producer-0.0.1-SNAPSHOT.jar

CMD ["java","-jar","employee-producer-0.0.1-SNAPSHOT.jar"]

Open the terminal and start the docker

systemctl start docker

Now open the terminal and go to the Spring Boot employee-producer project folder.
 Next we will build an image with the name producer.

docker image build -t employee-producer .

Next we will run the above image as a container named producer. Also we will be publishing the docker port 8080 to centos port 8080.

docker container run --name producer -p 8080:8080 -d employee-producer

So our employee container has started. We can test this by going to localhost:8080/employee, we will see that our application is deployed successfully.

• Employee Consumer
  • We have created and started a container named producer where we have deployed the employee-producer service.
    So the only change we will be making is while consuming the employee producer service we will be using this container named producer instead of localhost:8080.
    So in the ConsumerControllerClient class we will be having the base url as http://producer:8080/employee instead of http://localhost:8080/employee.

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package com.javainuse.controllers;

import java.io.IOException;

import org.springframework.http.HttpEntity;

import org.springframework.http.HttpHeaders;

import org.springframework.http.HttpMethod;

import org.springframework.http.MediaType;

import org.springframework.http.ResponseEntity;

import org.springframework.web.client.RestClientException;

import org.springframework.web.client.RestTemplate;

public class ConsumerControllerClient {

    public void getEmployee() throws RestClientException, IOException {

        String baseUrl = "http://producer:8080/employee";

        RestTemplate restTemplate = new RestTemplate();

        ResponseEntity<String> response=null;

        try{

        response=restTemplate.exchange(baseUrl,

                HttpMethod.GET, getHeaders(),String.class);

        }catch (Exception ex)

        {

            System.out.println(ex);

        }

        System.out.println(response.getBody());

    }

    private static HttpEntity<?> getHeaders() throws IOException {

        HttpHeaders headers = new HttpHeaders();

        headers.set("Accept", MediaType.APPLICATION_JSON_VALUE);

        return new HttpEntity<>(headers);

    }

}

• The docker file is as follows:

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From openjdk:8

copy ./target/employee-consumer-0.0.1-SNAPSHOT.jar employee-consumer-0.0.1-SNAPSHOT.jar

CMD ["java","-jar","employee-consumer-0.0.1-SNAPSHOT.jar"]

• Open the terminal and go to the Spring Boot employee consumer project folder.
   Next we will build an image with the name consumer.

docker image build -t employee-consumer.

• Next we will run the above image as a container named consumer.

docker image build -t employee-consumer.

• Next check the logs using

docker container logs consumer

• Here we can see that the container named consumer is not able to communicate with the container named producer.
• So we are getting a null pointer exception.

Inter Docker Container Communication Using Docker Networking

We will be using Docker Networking to allow multiple containers to interact with each other.

We will need to create our own network and add both the employee-producer and employee-consumer services to it. We will stop and remove the existing docker containers named consumer and producer.

Lets first check the available networks

docker network ls

Next we will create our own network will be of type bridge

docker network create consumer-producer

Lets start the employee producer container on the newly created network.

docker container run --network consumer-producer --name producer -p 8080:8080 

-d employee-producer 

Lets start the employee consumer+ container on the newly created network.

docker container run --network consumer-producer --name consumer 

-d employee-consumer 

Lets check the consumer container logs-

docker container logs consumer