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Use case 03

This use case shows how to facilitate local frontend development with backend run in remote cluster.

Prerequisities

  1. Install latest Kubectl client.

  2. Install latest Telepresence.

  3. Install latest Minikube.

Architecture

The diagram below depicts how to enable multi cluster development in k8s:

Alt text

Getting Started

Sample application that shows how to swap service in remote cluster with service running in local host.

Remote Cluster or Minikube

  1. Deploy backend and frontend applications in remote cluster:
kubectl apply -f backend.yaml,frontend.yaml
  1. Make sure frontend-, backend- pods and services are up and running:
kubectl get pods,svc

NAME                            READY   STATUS    RESTARTS   AGE
pod/backend-5cbcdfd67b-x2sbs         1/1     Running   0          23m
pod/frontend-7b77896f9b-5rnhc   1/1     Running   0          102s


NAME             TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
service/be-srv   ClusterIP   100.68.217.68   <none>        80/TCP    23m
service/fe-srv   ClusterIP   100.70.86.99    <none>        80/TCP    4m10s

Localhost

  1. Swap frontend service in remote cluster to forward requests to local server:
telepresence --swap-deployment frontend --namespace default  --run-shell
python3 -m http.server 8000

OR:

telepresence --swap-deployment frontend --namespace default --expose 8000 \
--run python3 -m http.server 8000
  1. Make sure a new frontend deployment created in place of existing one:
kubectl get pods,svc -n default

NAME                                                         READY     STATUS    RESTARTS   AGE
backend-59fd8d4bb7-69bxc                                     1/1       Running   0          4d
frontend-a59bdbf638fe4d36904aed7b7d4c8771-55988dd464-xfnsg   1/1       Running   0          24s
  1. In another terminal, make sure can reach frontend service running in remote cluster which forwards requests to local server:
curl http://frontend-srv.default:8000/

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Directory listing for /</title>
</head>
<body>
<h1>Directory listing for /</h1>
<hr>
<ul>
<li><a href=".git/">.git/</a></li>
<li><a href="backend/">backend/</a></li>
<li><a href="backend.yaml">backend.yaml</a></li>
<li><a href="frontend/">frontend/</a></li>
<li><a href="frontend.yaml">frontend.yaml</a></li>
<li><a href="helloworld.py">helloworld.py</a></li>
<li><a href="images/">images/</a></li>
<li><a href="portforwarding.md">portforwarding.md</a></li>
<li><a href="README.md">README.md</a></li>
<li><a href="telepresence_use_case_01.md">telepresence_use_case_01.md</a></li>
<li><a href="telepresence_use_case_02.md">telepresence_use_case_02.md</a></li>
<li><a href="telepresence_use_case_03.md">telepresence_use_case_03.md</a></li>
<li><a href="telepresence_use_case_04.md">telepresence_use_case_04.md</a></li>
</ul>
<hr>
</body>
</html>
  1. Make sure requests appear in local server logs:
python3 -m http.server 8000

T: Forwarding remote port 8000 to local port 8000.

Serving HTTP on 0.0.0.0 port 8000 (http://0.0.0.0:8000/) ...
127.0.0.1 - - [02/Nov/2018 13:45:40] "GET / HTTP/1.1" 200 -

Note: Exiting telepresence will restore frontend service running in remote cluster.

Uninstall

  1. Uninstall backend application in remote cluster:
kubectl delete -f backend.yaml,frontend.yaml
  1. To stop Telepresence, type 'exit' or CTRL-D in terminal telepresence is active.

References

Kubehelloworld project authored by Sal Rashid.

Authors

Opengov Devops team.