Docker / docker-compose / nginx / springboot

Question

I have two spring-boot microservices, order-service & payment-service. Both of them are connected to Eureka server. order-service makes a call to payment-service using feign.

Activity 1

I have used maven spotify plugin to create the docker image and a docker-compose file to create a network and make all services up and running. This is all perfect.

Activity 2

Now I need to scale the services. So I removed the host port in the docker-compose file and then ran the command as follows:

docker-compose up -d --scale order-service=2 --scale payment-service=2

This created 2 instances of the services and attached them to the eureka server.

docker-compose ps

The above command gave the following output

service-registry_order-service_1      sh -c java $JAVA_OPTS -Dja ...   Up       0.0.0.0:32776->8181/tcp, 8182/tcp
    service-registry_order-service_2      sh -c java $JAVA_OPTS -Dja ...   Up       0.0.0.0:32777->8181/tcp, 8182/tcp
    service-registry_payment-service_1    sh -c java $JAVA_OPTS -Dja ...   Up       8181/tcp, 0.0.0.0:32774->8182/tcp
    service-registry_payment-service_2    sh -c java $JAVA_OPTS -Dja ...   Up       8181/tcp, 0.0.0.0:32775->8182/tcp
    service-registry_service-registry_1   sh -c java $JAVA_OPTS -Dja ...   Up       0.0.0.0:8761->8761/tcp 

You can see that services are running in the available ports in the host system. Now I need to add a load balancer so that I don't have to bother about the port in which the service is running.

I followed the post here and added the nginx configuration

Step 1: Added the nginx.conf file as follows:-

user  nginx;

events {
    worker_connections   1000;
}
http {
        server {
              listen 4000;
              location / {
                proxy_pass http://order-service:8181;
              }
        }
}

Step 2: I have modified the docker-compose file to add nginx details. The final file looks like below:

version: '3.7'

networks:
  order-payment:

services:
  service-registry:
    image: shefzee/service-registry:0.0.1-SNAPSHOT
    ports:
      - "8761:8761"
    restart: always
    networks:
      - order-payment

  order-service:
    image: shefzee/order-service:0.0.1-SNAPSHOT
    ports:
      #- "8181:8181"
      - "8181"
    restart: always
    depends_on:
      - service-registry
      - payment-service
    networks:
      - order-payment


  payment-service:
      image: shefzee/payment-service:0.0.1-SNAPSHOT
      ports:
        #- "8182:8182"
        - "8182"
      restart: always
      depends_on:
        - service-registry
      networks:
        - order-payment

  nginx:
      image: nginx:latest
      volumes:
        - ./nginx.conf:/etc/nginx/nginx.conf:ro
      depends_on:
        - order-service
      ports:
        - "4000:4000"

Now, ran the docker-compose

docker-compose up -d --scale order-service=2 --scale payment-service=2

and, listed the containers..

               Name                              Command               State                  Ports              
-----------------------------------------------------------------------------------------------------------------
service-registry_nginx_1              nginx -g daemon off;             Exit 1                                    
service-registry_order-service_1      sh -c java $JAVA_OPTS -Dja ...   Up       0.0.0.0:32776->8181/tcp, 8182/tcp
service-registry_order-service_2      sh -c java $JAVA_OPTS -Dja ...   Up       0.0.0.0:32777->8181/tcp, 8182/tcp
service-registry_payment-service_1    sh -c java $JAVA_OPTS -Dja ...   Up       8181/tcp, 0.0.0.0:32774->8182/tcp
service-registry_payment-service_2    sh -c java $JAVA_OPTS -Dja ...   Up       8181/tcp, 0.0.0.0:32775->8182/tcp
service-registry_service-registry_1   sh -c java $JAVA_OPTS -Dja ...   Up       0.0.0.0:8761->8761/tcp      

If you see, nginx is not running. I am not able to figure out the issue here. Please help.

What I need is, if I do, http://localhost:4000/ uri , it should forward the request to any of the order-service instances.

Thanks !

Answer 1

I realized that I just need an API gateway and eureka will manage which instance it should route the request to.