Skupper Hello World private to private

Connect services in isolated on-prem sites

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 namespaces
• Step 3: Deploy the frontend and backend
• Step 4: Create your sites
• Step 5: Link your sites
• Step 6: Expose the backend
• Step 7: Access the frontend
• Cleaning up
• Summary
• Next steps
• About this example

Overview

This example is a basic multi-service HTTP application deployed across two Kubernetes clusters, each in its own private data center.

It contains two services:

• A backend service that exposes an /api/hello endpoint. It returns greetings of the form Hi, <your-name>. I am <my-name> (<pod>).

• A frontend service that connects to the backend. It sends greetings to the backend and fetches new greetings in response.

The backend service runs in on-prem cluster "private1", and the frontend service runs in on-prem cluster "private2". The private sites are linked by a relay site in the public cloud. Skupper enables the frontend to connect to the backend over a secure dedicated application network.

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 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

Private 1:

export KUBECONFIG=~/.kube/config-private1
# Enter your provider-specific login command
kubectl create namespace private1
kubectl config set-context --current --namespace private1

Private 2:

export KUBECONFIG=~/.kube/config-private2
# Enter your provider-specific login command
kubectl create namespace private2
kubectl config set-context --current --namespace private2

Relay:

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

Step 3: Deploy the frontend and backend

This example runs the frontend and the backend in separate Kubernetes namespaces, on different clusters.

Use kubectl create deployment to deploy the frontend in namespace private1 and the backend in namespace private2.

Private 1:

kubectl create deployment frontend --image quay.io/skupper/hello-world-frontend

Private 2:

kubectl create deployment backend --image quay.io/skupper/hello-world-backend --replicas 3

Step 4: Create your sites

A Skupper site is a location where components of your application are running. Sites are linked together to form a network for your application. In Kubernetes, a site is associated with a namespace.

For each namespace, use skupper init to create a site. This deploys the Skupper router and controller. Then use skupper status to see the outcome.

Note: If you are using Minikube, you need to start minikube tunnel before you run skupper init.

Private 1:

skupper init
skupper status

Sample output:

$ skupper init
Waiting for LoadBalancer IP or hostname...
Waiting for status...
Skupper is now installed in namespace 'private1'.  Use 'skupper status' to get more information.

$ skupper status
Skupper is enabled for namespace "private1". It is not connected to any other sites. It has no exposed services.

Private 2:

skupper init
skupper status

Sample output:

$ skupper init
Waiting for LoadBalancer IP or hostname...
Waiting for status...
Skupper is now installed in namespace 'private2'.  Use 'skupper status' to get more information.

$ skupper status
Skupper is enabled for namespace "private2". It is not connected to any other sites. It has no exposed services.

Relay:

skupper init
skupper status

Sample output:

$ skupper init
Waiting for LoadBalancer IP or hostname...
Waiting for status...
Skupper is now installed in namespace 'relay'.  Use 'skupper status' to get more information.

$ skupper status
Skupper is enabled for namespace "relay". It is not connected to any other sites. It has no exposed services.

As you move through the steps below, you can use skupper status at any time to check your progress.

Step 5: Link your sites

A Skupper link is a channel for communication between two sites. Links serve as a transport for application connections and requests.

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 Private 1 to generate the token. Then, use skupper link create in site Private 2 to link the sites.

Relay:

skupper token create ~/relay1.token
skupper token create ~/relay2.token

Sample output:

$ skupper token create ~/relay1.token
Token written to ~/relay1.token

$ skupper token create ~/relay2.token
Token written to ~/relay2.token

Private 1:

skupper link create ~/relay1.token

Sample output:

$ skupper link create ~/relay1.token
Site configured to link to https://10.106.89.17:8081/76f8f557-ccd2-11ee-865d-04421a4c5042 (name=link1)
Check the status of the link using 'skupper link status'.

Private 2:

skupper link create ~/relay2.token

Sample output:

$ skupper link create ~/relay2.token
Site configured to link to https://10.106.89.17:8081/775fb7d6-ccd2-11ee-aab9-04421a4c5042 (name=link1)
Check the status of the link using 'skupper link status'.

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 6: Expose the backend

We now have our sites linked to form a Skupper network, but no services are exposed on it. Skupper uses the skupper expose command to select a service from one site for exposure in all the linked sites.

Use skupper expose to expose the backend service in Private 2 to the frontend in Private 1.

Private 2:

skupper expose deployment/backend --port 8080

Sample output:

$ skupper expose deployment/backend --port 8080
deployment backend exposed as backend

Step 7: 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.

Private 1:

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:

Private 1:

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

Relay:

skupper delete

Private 2:

skupper delete
kubectl delete deployment/backend

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.