Learn to implement microservices across a range of common tech stacks.

Scalability & System Design for Developers

In this module, we’ll look at some fundamental concepts for implementing microservices. Within each concept, learn about the different technologies used to implement it. The technologies include front-end integration with Edge Side Includes (ESI), asynchronous microservices with Kafka and REST feeds, synchronous microservices with the Netflix stack, and Consul, Docker, Kubernetes, Cloud Foundry. Each technology is described and then demonstrated with real code.

Microservice Architecture: Practical Implementation

# Additional microservice
Supplement the Kubernetes system with an additional microservice.
  * A microservice that is used by a call center agent to create notes for a call can be used as an example. The call center agent should be able to select the customer. 
  * For calling the customer microservice the hostname
    `customer` has to be used.
  * Of course, you can copy and modify one of the existing microservices. 
  * Package the microservice in a Docker image and upload it into the
  Docker repository. This can be done by adapting the script
  `docker-build.sh`. 
  * Adapt `kubernetes-deploy.sh` in such a manner that the microservice is deployed. 
  * Adapt `kubernetes-remove.sh` in such a manner that the microservice is deleted. 

# Interactive tutorial 
<https://kubernetes.io/docs/getting-started-guides/> is an
interactive tutorial that shows how to use Kubernetes. It complements
this chapter well. Work through the tutorial to get an impression of
the Kubernetes features. 

# Run a rolling update
Kubernetes supports rolling updates. A new version of a pod is rolled out in such a way that there are **no interruptions to the service**. See 
  <https://kubernetes.io/docs/tasks/run-application/rolling-update-replication-controller/>.


Run a rolling update! To do this you need to create a new Docker image. The scripts for compiling and delivering to the Docker hub are included in the example. 

# Try a hosted solution
Cloud providers such as Google or Microsoft offer Kubernetes infrastructures, see  <https://kubernetes.io/docs/getting-started-guides/#hosted-solutions>.

Make the example work in such an environment! The scripts can be
  used without changes because `kubectl` also supports these technologies. 


# Test load balancing
 Test the load balancing in the example.
  * `kubectl scale` alters the number of pods in a replica set.
  `kubectl scale -h` indicates which options there are.
  For example, scale the replica set `catalog`. 
  * `kubectl get deployments` shows how many pods are running in the respective
    deployment. 
  * Use the service. For example, `minikube service
  apache` opens the web page with links to all microservices.
  Select the order microservice and get the orders displayed.
  * `kubectl describe pods -l run=catalog` displays the running pods.
  There you can also find the IP address of the pods in a line which
  starts with `IP`. 
  * Log into the Kubernetes node with `minikube ssh`.  To read out the metrics, you can use a command like `curl 172.17.0.8:8080/metrics`. You have to adapt the IP address. This way you can display the metrics of the catalog pods which Spring Boot creates. For example, the metrics contain the number of requests that have been responded with an HTTP 200 status code (OK). If you use the catalog microservice via the web page, each pod should process some of the requests and the metrics of all pods should go up.
  * Use `minikube dashboard` for observing the information in the dashboard. 

# Deploy Docker registry examples
 The example currently uses the public Docker hub. Install your own
  [Docker registry](https://docs.docker.com/registry/). Save the
  Docker images of the example in the registry and deploy the example
  from this registry.

# Kubernetes workshop
 At <https://github.com/GoogleCloudPlatform/kubernetes-workshops>
  you can find material for a Kubernetes workshop to further
  familiarize yourself with this system.

# Port asynchronous examples to Kubernetes
Port the Kafka example (see [chapter 7](https://www.educative.io/courses/microservice-architecture-practical-implementation/introduction-B15YQD66Qrk)) or the Atom example (see [chapter 8](https://www.educative.io/courses/microservice-architecture-practical-implementation/introduction-m2yWAKYG6p0)) to
  Kubernetes.

This shows how asynchronous microservices can also run in a Kubernetes cluster. Kafka stores data, which can be difficult
in a Kubernetes system. Explore how to run a Kafka cluster in a Kubernetes system in production.

# Familiarize yourself with the log
Use `kubectl logs -help` for familiarizing yourself with the log
administration in Kubernetes.

 Take a look at the logs of at least two
microservices.

# Checkout logs of some pods
Use [kail](https://github.com/boz/kail) for displaying the logs of
some pods.


In this lesson, we'll look at some fun experiments you can try.

Experiments

Additional microservice