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[L4] update lab session #9

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256 changes: 91 additions & 165 deletions docs/lab-4.md
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# Deployment and Networking in Kubernetes
# Kubernetes Networking

Lab Session 4 - 7 Nov, 2024
Lab Session 4 - 29 Oct, 2025

# Introduction
## Introduction

The goal of this lab session is to let you practice the basics of
deployment and networking in Kubernetes, which includes the creation of
a ReplicaSet, the creation of a Deployment, the ability to read and edit
Kubernetes manifests in YAML, the configuration of commonly used
networking solutions, and the operations associated to these objectives.
The goal of this lab session is to let you practice the networking
basics in Kubernetes and apply them in real-world scenarios, i.e. in
multiple environments and in cross-team collaboration.

To submit the answers to this lab session, please fill in your answers
in this document in-place. This should be done before the beginning of
the next course.

## Exercise 1 - ReplicaSet
## Exercise 1 - Hello Server

Create a new ReplicaSet with 2 replicas and the Docker image
`nginx:1.26` and call this resource `nginx`. Use labels
`school=esigelec`, `app=nginx`, `team=${team}`, and `tier=frontend` for
both the ReplicaSet and the underlying pods. The pods should expose the
container port 80 to receive incoming traffic. The name of the container
should also be “nginx”. Persist the Kubernetes manifest (YAML file) in
the Git repository of your team under the `k8s` directory as file
`replicaset-nginx.yaml`.
Expose the demo application
[`hello-server`](https://hub.docker.com/r/mincongclassroom/hello-server)
in Kubernetes.


Create a new Deployment called `hello-server-deployment` for the
application `hello-server`
(https://hub.docker.com/r/mincongclassroom/hello-server). This is the
image that you have fixed in Lab Session 1. The Deployment should have 1
replica. Then, expose the application as an internal Service called
`hello` in Kubernetes, under the port 80. Validate that the
implementation is working and document it in this page.

    *\[answer: optional. Commit code changes directly under the `k8s`
directory.\]*
## Exercise 2 - PetClinic Microservice


Under the existing stack of the Spring PetClinic (deployed in Lab
Session 3), expose the API gateway as a Service of type NodePort under
the port `30000`. Validate that the solution implementation is working
and document it in this page.

  
## Exercise 3 - PetClinic Environments

Scale this ReplicaSet to 3 replicas using `kubectl` and provide your
command below.
Create two namespaces: `prod` and `dev`. Each namespace should contain
the whole stack in microservice, including the API gateway and the
backend services.


- In the prod namespace, use version `3.0` of the Docker images, created
in Lab Session 3. All resources should contain the label `env=prod`.
- In the dev namespace, use version `3.0` of the Docker images, created
in Lab Session 3. Note: later on, they will be replaced by new images
`4.x` created in this session. All resource should contain the label
`env=dev`.

    *\[answer\]*
Also, add the label `clinic=${clinic}`. Is the Pet Clinic still
accessible? If not, please fix it. Describe your observations and fixes
in this page.

  
## Exercise 4 - Cross-team Collaboration


In this exercise, you will collaborate with other teams to improve the
Pet Clinic service together in the `dev` namespace. Each team uses the
Kubenetes cluster in your computer, but you can deploy new Docker image
to update the logic of the microservices, and update the Kubernetes
resources (Deployment, Service, …) to change your infrastructure.

Delete one of the pods from this ReplicaSet, how many pods do you have
now? Why?
## Exercise 4C - Email Support


The pet owners are managed by the `customers-service`. Currently,
registering an owner does not require an email. But this is an important
way of communication nowadays. Could you add this feature? You should
implemente the backend logic and collaborate with the frontend team for
the frontend logic.

    *\[answer\]*
Here are some requirements:


- In the UI, the owner registration form should contain a new field
“Email”
- In the UI, email should be read-only when editing owner’s information
- In the UI, email should be displayed in the owner page
- In the backend, the email should be validated
- In the backend, the email information should be persisted in the
database
- In the backend, the email should be part of the Owner Listing API


The result should be built and deployed as image `4.x` in DockerHub
(e.g. `4.0`, `4.1`, …). Don’t overwrite existing images. If you need
additional changes, push another image.

## Exercise 2 - Deployment
Describe what you implemented here, including key code changes, UI
changes. Also, how you validate your changes.

Create a new Deployment with 2 replicas using the Docker image
`mincongclassroom/weekend-server-${team}` that you built in the previous
lab session and call this deployment `weekend-server`. Use labels
`school=esigelec`, `app=weekend-server`, `team=${team}`, and
`tier=backend` for both the Deployment and the underlying pods. Persist
the Kubernetes manifest (YAML file) in the Git repository of your team
under the `k8s` directory as file `deployment-weekend-server.yaml`.
## Exercise 4V - Veterinarian Qualification

In addition to the changes above, please also
The pet owners needs more information from the veterinarians before
trusting them to treat their pets. Please add a field “diplomas” to
represent a list of additional diplomas that the veterinarian has. It
helps justifying his/her specialization. You can use the following
abbreviations:

- Add environment variable `APP_TEAM` in the manifest to describe your
team for the container
- Add environment variable `APP_AUTHORS` in the manifest to describe
yourselves as authors of the container. The format should be
“Firstname1 LASTNAME1, Firstname2 LASTNAME2”, such as “Emmanuel
MACRON”.
- Propagate the pod name to the container.
- `DESV`: Diplôme d’Études Spécialisées Vétérinaires — equivalent to a
French medical specialization.
- `CES`: Certificat d’Études Spécialisées — an older qualification, but
still valid.
- `DIPL`: European or American “Diplomate” titles (e.g. Dipl. ECVS for
surgery, Dipl. ECVIM for internal medicine, etc.) — these represent
the highest level of expertise recognized internationally.

  
Here are some requirements

    *\[answer: optional. Commit code changes directly under the `k8s`
directory.\]*
- This new field should be part of the Veterinarians Listing API
- This new field should be displayed in the Veterinarians page
- This new field should be persisted in the database


Then, create a new API to register a veterinarian, similar to the “owner
registration”.

  
## Exercise 4F - UI Support

Do you see a ReplicaSet related to your deployment? If yes, write down
the name of the ReplicaSet, else please share your thoughts. Hint: you
can use the command `kubectl get all` to list all the resources in your
Kubernetes cluster under the current namespace.
Collaborate with the Customers team and the Veterinarian team to support
the new use cases: the email of the customer, and the diplomas of the
veterinarians.

  
Email support:

    *\[answer\]*
- The owner registration form should contain a new field “Email”
- Email should be read-only when editing owner’s information
- Email should be displayed in the owner page

  
Veterinarians support:



Scale up the deployment to 3 replicas and share the command below.



    *\[answer\]*





Upgrade the Docker image of the weekend-server deployment by setting the
image to another version that you built. Roll out this change and
observe the status of the Pods, ReplicaSet, and Deployment. Please
describe your observation here.



    *\[answer\]*





Inspect the revision history of your deployment.



    *\[answer\]*





What if you specify an image that does not exist?

    *\[answer\]*





## Exercise 3 - Service

Provide a networking solution for weekend-server application so that
this deployment is exposed to other resources inside the Kubernetes
cluster. Please ensure that access is only granted for resources within
the Kubernetes cluster, access from external systems is not allowed.
Persist the Kubernetes manifest (YAML file) in the Git repository of
your team under the `k8s` directory as file
`service-weekend-server.yaml`.



    *\[answer: optional. Commit code changes directly under the `k8s`
directory.\]*





Port forward to that service by listening to port 8080 of your machine
and forwarding data to your service weekend-server to verify that the
service is working as expected. Please share the kubectl command.



    *\[answer\]*





Use another to verify that this is working as expected. Please create a
helper pod with the image
[curlimages/curl](https://hub.docker.com/r/curlimages/curl) using the
command below. Try to use different DNS queries to send HTTP requests to
the service. Reminder: after starting the curl image, you can use `curl`
command followed by the URL to make an HTTP request. You can exit the
pod by pressing CTRL + D (‘D’ stands for disconnect).

``` sh
kubectl run curl-pod --image=curlimages/curl --restart=Never --rm -it -- /bin/sh
# curl ${URL}
```

Here is a reminder of different expressions:

| Form | Expression |
|:---|:---|
| Short form | `${service}` |
| Namespace qualified | `${service}.${namespace}` |
| Service domain | `${service}.${namespace}.svc` |
| Fully qualified domain name (FQDN) | `${service}.${namespace}.svc.cluster.local` |

Please provide the commands and results below.



    *\[answer\]*


- Diplomas should be part of the Verterinarians Listing
- A new page should be created for registering a new Verterinarian