Service Discovery Demo with Smartstack
This is an example of how to use Smartstack in Docker containers to enable Service Discovery between microservices.
This demo was part of the Microservices, Docker and Service Discovery talk at the Docker Rennes meetup in May 2015.
Requirements
To run this Demo you will only need Docker.
If you wish to make changes to the services and build your own images, you will also need:
- Java 8
- Gradle
- NodeJS / npm
What does the demo do?
There are 2 services:
- Color UI Service, which displays colors (but doesn't know how to generate them itself) - using NodeJS and AngularJS
- Color Service, which provides a random color selected at startup (but doesn't display it) - using Java (Dropwizard)
The idea is to allow these 2 services to work together, so that the Color UI Service can get a color from the Color Service and display it. When an instance of the Color service is started, it picks a color randomly and will always return that color when recieving a request. This allows to get a visual feedback as to which Color Service is being used by the UI.
Running this Demo
Start Zookeeper
Smartstack relied on Zookeeper as a key-value store to keep track of all the discovery information.
You can start use your own Zookeeper, or simply start it in container (and expose it to the host on port 2181):
docker run -d --name=zookeeper -p 2181:2181 jplock/zookeeper
Start the Color UI Service
docker run -d -e ZK_HOSTS=<ZK_HOST>:2181 -p 80:80 pierrevincent/discovery-demo-color-ui-service
Replace <ZH_HOST> with your Docker Host IP. If you're using docker-machine on MacOS it's likely to be 192.168.99.100. If you're on Linux, then simply use 127.0.0.1. You can also find the IP Address of the Zookeeper container by inspecting the container directly with docker inspect --format '{{ .NetworkSettings.IPAddress }}' zookeeper.
You should then be able to access the Color UI on http://192.168.99.100 (or http://127.0.0.1 on Linux). The page should display that there is no color available, since there is no Color Service available yet.
Start the Color Service
docker run -d -e ZK_HOSTS=<ZK_HOST>:2181 pierrevincent/discovery-demo-color-service
You should then start seeing a color appearing on the Color UI in your browser (started in previous section).
Play around
You can now try a few things to see how the Discovery takes care of changes:
- shut down a container that runs a Color Service
- start multiple containers of the Color Service
- access the Color UI service in multiple browser tabs
- ...
Smartstack Docker images
Smartstack is an open-source service discovery framework developed by Airbnb.
This demo relies on the following base smartstack images: