Summary

Three web applications are run in one K3s server instance and accessible depending on the Host used when making a request to the IP address 192.168.42.11.

Application 1 has 1 replica and is accessible if request includes a header Host: app1.com
Application 2 has 3 replicas and is accessible if request includes a header Host: app2.com
Application 3 has 1 replica and is accessible by default or contains undefined value of request header Host.

View diagram of p2's environment

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Start and provision the vagrant environment of p2

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vagrant up
Bringing machine 'suchoS' up with 'virtualbox' provider...
==> suchoS: Importing base box 'centos/7'...
    [...]
    suchoS: [INFO]  systemd: Starting k3s
    suchoS: service/app-one created
    suchoS: deployment.apps/app-one created
    suchoS: service/app-two created
    suchoS: deployment.apps/app-two created
    suchoS: service/app-three created
    suchoS: deployment.apps/app-three created
    suchoS: ingress.networking.k8s.io/ingress-applications created

Check created resources such as pods, services, deployments and replicas

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vagrant ssh suchoS --command "kubectl get all"
NAME                             READY   STATUS    RESTARTS   AGE
pod/app-one-7454877f6d-ndx7f     1/1     Running   0          36m
pod/app-two-867df7fb47-8rb9b     1/1     Running   0          36m
pod/app-two-867df7fb47-tsrdt     1/1     Running   0          36m
pod/app-three-5467985dbb-cg2n7   1/1     Running   0          36m
pod/app-two-867df7fb47-tzk98     1/1     Running   0          36m

NAME                 TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGE
service/app-one      ClusterIP   10.43.246.0   <none>        80/TCP    37m
service/app-two      ClusterIP   10.43.99.33   <none>        80/TCP    37m
service/app-three    ClusterIP   10.43.77.88   <none>        80/TCP    37m
service/kubernetes   ClusterIP   10.43.0.1     <none>        443/TCP   37m

NAME                        READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/app-one     1/1     1            1           37m
deployment.apps/app-three   1/1     1            1           37m
deployment.apps/app-two     3/3     3            3           37m

NAME                                   DESIRED   CURRENT   READY   AGE
replicaset.apps/app-one-7454877f6d     1         1         1       36m
replicaset.apps/app-three-5467985dbb   1         1         1       36m
replicaset.apps/app-two-867df7fb47     3         3         3       36m
Connection to 127.0.0.1 closed.

View Ingress

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vagrant ssh suchoS --command "kubectl describe ingress"
Name:             ingress-applications
Namespace:        default
Address:          192.168.42.110
Default backend:  app-three:80 (10.42.0.9:8080)
Rules:
  Host        Path  Backends
  ----        ----  --------
  app1.com
              /   app-one:80 (10.42.0.2:8080)
  app2.com
              /   app-two:80 (10.42.0.11:8080,10.42.0.5:8080,10.42.0.6:8080)
  *
              /   app-three:80 (10.42.0.9:8080)
Annotations:  <none>
Events:       <none>
Connection to 127.0.0.1 closed.

Browse to check that the virtual machine is correctly configured

Using curl

app1 with one replica

[~]$ curl -sH "Host:app1.com" 164.92.153.174 | grep app
  Hello from app1.
      <td>app-one-7454877f6d-ndx7f</td>

app2 with three replicas

[~]$ curl -sH "Host:app2.com" 164.92.153.174 | grep app
  Hello from app2.
      <td>app-two-867df7fb47-tsrdt</td>
[~]$ curl -sH "Host:app2.com" 164.92.153.174 | grep app
  Hello from app2.
      <td>app-two-867df7fb47-8rb9b</td>
[~]$ curl -sH "Host:app2.com" 164.92.153.174 | grep app
  Hello from app2.
      <td>app-two-867df7fb47-tzk98</td>

app3 with one replica as default application

[~]$ curl -sH "Host:app3.com" 164.92.153.174 | grep app
  Hello from app3.
      <td>app-three-5467985dbb-cg2n7</td>
[~]$ curl -sH "Host:42.fr" 164.92.153.174 | grep app
  Hello from app3.
      <td>app-three-5467985dbb-cg2n7</td>
[~]$ curl -s  164.92.153.174 | grep app
  Hello from app3.
      <td>app-three-5467985dbb-cg2n7</td>