Patient Portal

A simple database-backed web application that runs in the public cloud but keeps its data in a private database

This example is part of a suite of examples showing the different ways you can use Skupper to connect services across cloud providers, data centers, and edge sites.

Contents

• Overview
• Prerequisites
• Step 1: Install the Skupper command-line tool
• Step 2: Set up your Kubernetes namespaces
• Step 3: Set up your Podman network
• Step 4: Deploy the application
• Step 5: Create your sites
• Step 6: Link your sites
• Step 7: Expose application services
• Step 8: Access the frontend
• Cleaning up
• Summary
• Next steps
• About this example

Overview

This example is a simple database-backed web application that shows how you can use Skupper to access a database at a remote site without exposing it to the public internet.

It contains three services:

• A PostgreSQL database running on a bare-metal or virtual machine in a private data center.

• A payment-processing service running on Kubernetes in a private data center.

• A web frontend service running on Kubernetes in the public cloud. It uses the PostgreSQL database and the payment-processing service.

The example uses two Kubernetes namespaces, private and public, to represent the Kubernetes cluster in the private data center and the cluster in the public cloud. It uses Podman to run the database.

Prerequisites

• The kubectl command-line tool, version 1.15 or later (installation guide)

• Access to at least one Kubernetes cluster, from any provider you choose

Step 1: Install the Skupper command-line tool

This example uses the Skupper command-line tool to deploy Skupper. You need to install the skupper command only once for each development environment.

On Linux or Mac, you can use the install script (inspect it here) to download and extract the command:

curl https://skupper.io/install.sh | sh

The script installs the command under your home directory. It prompts you to add the command to your path if necessary.

For Windows and other installation options, see Installing Skupper.

Step 2: Set up your Kubernetes namespaces

Skupper is designed for use with multiple Kubernetes namespaces, usually on different clusters. The skupper and kubectl commands use your kubeconfig and current context to select the namespace where they operate.

Your kubeconfig is stored in a file in your home directory. The skupper and kubectl commands use the KUBECONFIG environment variable to locate it.

A single kubeconfig supports only one active context per user. Since you will be using multiple contexts at once in this exercise, you need to create distinct kubeconfigs.

For each namespace, open a new terminal window. In each terminal, set the KUBECONFIG environment variable to a different path and log in to your cluster. Then create the namespace you wish to use and set the namespace on your current context.

Note: The login procedure varies by provider. See the documentation for yours:

• Minikube
• Amazon Elastic Kubernetes Service (EKS)
• Azure Kubernetes Service (AKS)
• Google Kubernetes Engine (GKE)
• IBM Kubernetes Service
• OpenShift

Public:

export KUBECONFIG=~/.kube/config-public
# Enter your provider-specific login command
kubectl create namespace public
kubectl config set-context --current --namespace public

Private:

export KUBECONFIG=~/.kube/config-private
# Enter your provider-specific login command
kubectl create namespace private
kubectl config set-context --current --namespace private

Step 3: Set up your Podman network

Open a new terminal window and set the SKUPPER_PLATFORM environment variable to podman. This sets the Skupper platform to Podman for this terminal session.

Use podman network create to create the Podman network that Skupper will use.

Use systemctl to enable the Podman API service.

Podman:

export SKUPPER_PLATFORM=podman
podman network create skupper
systemctl --user enable --now podman.socket

If the systemctl command doesn't work, you can try the podman system service command instead:

podman system service --time=0 unix://$XDG_RUNTIME_DIR/podman/podman.sock &

Step 4: Deploy the application

Use kubectl apply to deploy the frontend and payment processor on Kubernetes. Use podman run to start the database on your local machine.

Note: It is important to name your running container using --name to avoid a collision with the container that Skupper creates for accessing the service.

Note: You must use --network skupper with the podman run command.

Public:

kubectl apply -f frontend/kubernetes.yaml

Private:

kubectl apply -f payment-processor/kubernetes.yaml

Podman:

podman run --name database-target --network skupper --detach --rm -p 5432:5432 quay.io/skupper/patient-portal-database

Step 5: Create your sites

Public:

skupper init

Private:

skupper init --ingress none

Podman:

skupper init --ingress none

Step 6: Link your sites

Creating a link requires use of two skupper commands in conjunction, skupper token create and skupper link create.

The skupper token create command generates a secret token that signifies permission to create a link. The token also carries the link details. Then, in a remote site, The skupper link create command uses the token to create a link to the site that generated it.

Note: The link token is truly a secret. Anyone who has the token can link to your site. Make sure that only those you trust have access to it.

First, use skupper token create in site Public to generate the token. Then, use skupper link create in site Private to link the sites.

Public:

skupper token create --uses 2 ~/secret.token

Private:

skupper link create ~/secret.token

Podman:

skupper link create ~/secret.token

If your terminal sessions are on different machines, you may need to use scp or a similar tool to transfer the token securely. By default, tokens expire after a single use or 15 minutes after creation.

Step 7: Expose application services

In Private, use skupper expose to expose the payment processor service.

In Podman, use skupper service create and skupper service bind to expose the database on the Skupper network.

Then, in Public, use skupper service create to make it available.

Note: Podman sites do not automatically replicate services to remote sites. You need to use skupper service create on each site where you wish to make a service available.

Private:

skupper expose deployment/payment-processor --port 8080

Podman:

skupper service create database 5432
skupper service bind database host database-target --target-port 5432

Public:

skupper service create database 5432

Step 8: Access the frontend

In order to use and test the application, we need external access to the frontend.

Use kubectl expose with --type LoadBalancer to open network access to the frontend service.

Once the frontend is exposed, use kubectl get service/frontend to look up the external IP of the frontend service. If the external IP is <pending>, try again after a moment.

Once you have the external IP, use curl or a similar tool to request the /api/health endpoint at that address.

Note: The <external-ip> field in the following commands is a placeholder. The actual value is an IP address.

Public:

kubectl expose deployment/frontend --port 8080 --type LoadBalancer
kubectl get service/frontend
curl http://<external-ip>:8080/api/health

Sample output:

$ kubectl expose deployment/frontend --port 8080 --type LoadBalancer
service/frontend exposed

$ kubectl get service/frontend
NAME       TYPE           CLUSTER-IP      EXTERNAL-IP     PORT(S)          AGE
frontend   LoadBalancer   10.103.232.28   <external-ip>   8080:30407/TCP   15s

$ curl http://<external-ip>:8080/api/health
OK

If everything is in order, you can now access the web interface by navigating to http://<external-ip>:8080/ in your browser.

Cleaning up

To remove Skupper and the other resources from this exercise, use the following commands.

Public:

skupper delete
kubectl delete service/frontend
kubectl delete deployment/frontend

Private:

skupper delete
kubectl delete deployment/payment-processor

Podman:

skupper delete
podman stop database-target

Next steps

Check out the other examples on the Skupper website.

About this example

This example was produced using Skewer, a library for documenting and testing Skupper examples.

Skewer provides utility functions for generating the README and running the example steps. Use the ./plano command in the project root to see what is available.

To quickly stand up the example using Minikube, try the ./plano demo command.