Docker and Eureka with Spring Boot failing to register clients

Question

I have a very simple demo of using Spring Boot + Docker Compose + Eureka.

My server runs on port 8671 with the following application properties:

server:
  port: 8761
eureka:
  instance:
    prefer-ip-address: true
  client:
    registerWithEureka: false
    fetchRegistry: false
  server:
    waitTimeInMsWhenSyncEmpty: 0

My Eureka client runs on port 9000 with the following application properties:

server:
  port: 9000
spring:
  application:
    name: user-registration
eureka:
  client:
    registerWithEureka: true
    fetchRegistry: true
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
  instance:
    prefer-ip-address: true

When I start up my docker.compose file in the parent maven project, this is the contents of my docker-compose file:

eureka-server:
  image: rosenthal/eureka-server
ports:
   - "8761:8761"
user-registration:
  image: rosenthal/user-registration
  ports:
   - "9000:9000"
  links:
   - eureka-server

When I run my application by first starting the eureka server, following by the client via

mvn spring-boot:run 

The server successfully registers my client (I call it user-registration).

When I run my application through docker-compose, the client fails to register with the following output:

 DiscoveryClient_USER-REGISTRATION/0fd640cbc3ba:user-registration:9000: 
 registering service...
 user-registration_1  | 2017-06-21 04:36:05.120 ERROR 1 --- [nfoReplicator-0]        
 c.n.d.s.t.d.RedirectingEurekaHttpClient  : Request execution error
 user-registration_1  | 
 user-registration_1  | com.sun.jersey.api.client.ClientHandlerException: 
 java.net.ConnectException: Connection refused (Connection refused)

My first assumption was that running docker-compose ran into a race condition on waiting for the server to start, but my eureka client seems to have a heartbeat trying to call home to the server it's configured with. This means it's just not able to find the Eureka server I have registered (and is running, I can navigate to it on localhost:8671).

What am I missing here? Everything runs fine running locally with spring-boot starting up with it's own embedded tomcat containers. As soon as I start to do it with docker-compose, it doesn't want to work.

EDIT

I realized my problem, I believe. So docker doesn't run on localhost, it runs on the public IP it is assigned when I start up docker. Navigating to this ip + port shows my service running for Eureka Server. The client still doesn't register.

SO, I made changes to the application.yml file for my eureka client to:

serviceUrl:
  defaultZone: http://192.168.59.103:8761/eureka/

That IP is the one my docker daemon is running under. Now, it misses the first registration when I do docker-compose, but the second heartbeat picks up my client.

How can I ensure the client waits until the server is FULLY up? I used the proper docker "links" field in my docket compose file, but it didn't work as I hoped. Additionally, how can I see the defaultZone file to be my DOCKER_HOST IP?

Final result

The resulting docker-compose file that got everything working for me was:

eureka-server:
  image: thorrism/eureka-server
  ports:
   - "8761:8761"
user-registration:
  image: thorrism/user-registration
  ports:
   - "9000:9000"
  links:
   - eureka-server
  environment:
    EUREKA_CLIENT_SERVICEURL_DEFAULTZONE: http://eureka-server:8761/eureka

Answer 1

Set an environment property to override the eureka.client.serviceUrl.defaultZone to match the service name in your docker compose file.

eureka-server:
  image: rosenthal/eureka-server
  ports:
   - "8761:8761"
user-registration:
  image: rosenthal/user-registration
  ports:
   - "9000:9000"
  environment:
   - EUREKA_CLIENT_SERVICEURL_DEFAULTZONE: http://eureka-server:8761/eureka

This will override the property from the packaged application.properties.

NOTE: As mentioned in the comments you don't need the links section in the compose file. I removed is as such. See https://docs.docker.com/compose/networking/ for info on that.

Answer 2

If useful for you, that's in some way how I configure it for my production environment (docker-compose file version 2):

version: '2'
services:
  eureka-server:
    image: rosenthal/eureka-server
    expose:
    - "8761"
  user-registration:
    image: rosenthal/user-registration
    container_name: user-registration
    ports:
    - "9000:8080"
    environment:
      server.port: 8080
      eureka.client.enabled: 'true'
      eureka.host: eureka-server
      eureka.instance.preferIpAddress: 'true'

From the docs that's what expose does:

Expose ports without publishing them to the host machine - they’ll only be accessible to linked services. Only the internal port can be specified.

As you've got everything in the same network, containers can see each other with no links between them.

SIDE NOTE

Keep in mind that with this configuration port 9000 will be publicly accessible at the host machine, and mapped to the 8080 port of the user-registration container.

Answer 3

UPDATE:

It looks like for the newer versions of spring-boot (in my case 2.4.5) this solution does not work. The EUREKA_CLIENT_SERVICEURL_DEFAULTZONE property is not picked up automatically. There is a permanent issue with camelcasing which creates an inconsistency. EUREKA_CLIENT_SERVICEURL_DEFAULTZONE is not converted to eureka.client.serviceUrl.defaultZone. It's converted to eureka.client.serviceurl.defaultzone. Please look to this Github Issue for spring-cloud-netflix for more details. They cannot change the parameter now as this will break backward compatibility. Here is the code that finally worked for me

   discovery:
     container_name: discovery
     build: .
     ports:
       - "8761:8761"

   user-registration:
     container_name: user-registration
     build: .
     ports:
       - "8080:8080"
     environment:
       SPRING_APPLICATION_JSON: '{"eureka":{"client":{"serviceUrl":{"defaultZone":"http://discovery:8761/eureka"}}}}'

For only this property to set through environment variable you have to user SPRING_APPLICATION_JSON. It's ugly but it works.

Answer 4

i had the same issue and i tried everything but it did not work. after 2 weeks of trial and error then i tried to remove all the dependency from the repository and then i made sure that i have the same netflix client, server and Zuul dependency in all of them.

and then i used the above solutions after which it worked for me.

also be aware that u need to start the Services with docker compose only then it will work or else if u start them independently then they will all start in their on containers and will not register with the service registry. hope this helps

Answer 5

As an alternative to @Tanbir Sagar solution this was the one that worked for me:

discovery:
  container_name: discovery
  build: .
  ports:
    - "8761:8761"

user-registration:
  container_name: user-registration
  build: .
  ports:
    - "8080:8080"
  environment:
    eureka.client.serviceUrl.defaultZone: http://discovery:8761/eureka

Tested with Spring Boot 2.5.6 and Docker Compose 3.