Cloud Project

This project was the evaluation of the Cloud Computing discipline, PPGTI2001, from the UFRN master's degree. It needs to create a pod with multiple containers, it must be raised and it must meet the following requirements:

• The pod must have 4 containers and must be created using a Kubernetes manifest (yaml file);

Students:

• Ramon Domingos Duarte Oliveira [20231026233]
• Gerfesson Santos da Nobrega [20231026206]

About applications

API

Product registration API

{
"name": "PEN_BLACK",
"description": "black pen, with transparent body",
"qtdAvailable": 12
}

• /product (get, post)
• /product/:id (put, delete, get)

FRONT

Application that consumes the API, displaying listings and forms. Using https://refine.dev/ as a base template.

Docker-compose

For run using only docker-compose use

docker-compose up

services:

• mongo: MongoDB for product registration
• redis: Cache for frequent requests
• api : REST api to connect to the database.
• front: Front using React.

Kubernets

Step 1: Send this images for personal DockerHub (optional)

To build api image

cd api
docker build -t <your_username>/api-products .
docker push  <your_username>/api-products

To build front image

cd frontend
docker build -t <your_username>/front-products .
docker push  <your_username>/front-products

If you create custom images, go to the k8s/*-deployment files and change the image to yours.

The images MONGO and REDIS is oficial images, are already available on dockerhub for use.

It is expected that the machine environment is already pre-configured, and masters a workers joined, using kubeadm join --token command

Step 2: Create namespace

kubectl get ns
kubectl create namespace products-application
kubectl get ns
kubectl config get-contexts
kubectl config set-context --current --namespace=products-application

[output]

kubectl config set-context --current --namespace=products-application

kubectl config get-contexts

[output]

CURRENT	NAME	CLUSTER	AUTHINFO	NAMESPACE
*	kubernetes-admin@kubernetes	kubernetes	kubernetes-admin	products-api

Step 3: create a Deployment

In the deployment files, has details about the image docker and a imagePullPolicy. In this example is Always, for Always deploy get a new image for dockerhub. The line command is

 kubectl create deployment redis --image=redis --port=5701

but, in k8s directory has 4 yaml files to [api,front,mongo,redis]-deployment.yaml

Step 4: create a service

for expose the application for outside k8s, its necessary create a service You can create with a command:

kubectl create service nodeport web-products --tcp=3000:3000 --node-port=30300

check the creation

kubectl get service

NAME	TYPE	CLUSTER-IP	EXTERNAL-IP	PORT(S)	AGE
web-products	NodePort	10.97.135.212	3000:30300	TCP	3s

but, in k8s directory has 4 yaml files to [api,front,mongo,redis]-service.yaml

Step 5: Send files for MASTER node.

inthe folder k8shas 9 files deployment and service for [api, front, mongo and Redis]

and 1 file for ingress;

send this file for your master ( can use scp)

scp k8s/*  remote_username@10.10.0.2:/remote/directory

Step 6: Apply spec file

In sequence need apply this file, and check pods.

kubectl apply -f . 

[output]

For apply all files use kubectl apply -f . [output]

~kubectl apply -f .
deployment.apps/api created
service/api created
deployment.apps/front created
service/front created
deployment.apps/mongo created
service/mongo created
deployment.apps/redis-service created
service/redis-service created

kubectl get pods

[output]

NAME	READY	STATUS	RESTARTS	AGE
web-products	0/4	ContainerCreating	0	40s

while containers are created, check the logs with:

kubectl logs web-products

If it takes a long time to successfully create the containers, check the logs individually to see if any errors occurred, if necessary correct and apply this file again.

kubectl logs web-products -c [redis-service, mongo, frontend, api]

erro example:

NAME	READY	STATUS	RESTARTS	AGE
web-products	3/4	CrashLoopBackOff	12 (24s ago)	10m

after a few seconds, you can run this same command, and will see:

NAME	READY	STATUS	RESTARTS	AGE
web-products	4/4	Running	0	22s

Step 7: Check your application.

Go to browser, visit http://<ip-worker>:3000 and see the applcation.

3000 is the port that expose in yaml files.

Personal learning

• In our scenario, we need to expose the api, since the requests made by the front were client-side, using an internal IP would not work.
• All pods have many environment variables in the format <NAME>_SERVICE_HOST to identify other services, and can be used in yaml as configuration envs. Example line 39.
• To see all envs you can use kubectl exec <pod-name> printenv.
• Other format for URL is <service-name>.<namespace|default>.svc.cluster.local:<service-port>;