Secure a single-page app workload

This tutorial tells you how to secure a sample single-page Angular app Workload with Application Single Sign-On (commonly called AppSSO), which runs on Tanzu Application Platform (commonly known as TAP).

Follow these steps to deploy a sample single-page app Workload:

Get the sample application.
Create a namespace for workloads.
Claim client credentials.
Verify application authentication settings.
Start a sample back end.
Deploy the Workload.

Get the sample application

Follow these steps to fetch the single-page Angular app source code:

Download the Angular Frontend accelerator from the Tanzu Developer Portal accelerators located on your Tanzu Application Platform cluster:
- Option 1: Use the Tanzu Developer Portal dashboard by using a browser.
  
  Navigate to Application Accelerators and choose the Angular Frontend accelerator and then select the Single Sign-on option.
- Option 2: Use the Tanzu Accelerator CLI.
  
  Download the zip file of the accelerator source code and identify your AuthServer Issuer URI by running:
```
kubectl get authserver -A
```
  Generate the accelerator by using the tanzu accelerator CLI:
```
tanzu accelerator generate angular-frontend \
  --server-url TAP-GUI-SERVER-URL \
  --options '{
    "useSingleSignOn": true,
    "authority": "AUTHSERVER-ISSUER-URI",
    "namespace": "my-apps",
    "authorityLabelKey": "my-sso",
    "authorityLabelValue": "true"
  }'
```
Unzip the resulting .zip file into the angular-frontend directory in your workspace:
```
unzip angular-frontend
cd angular-frontend
git init
git branch -M main
git remote add origin YOUR-ACCELERATOR-GIT-REPOSITORY
git push origin main -u
```
For public clients, the AuthServer only supports the Authorization Code Flow: response_type=code, because public clients such as single page apps cannot safely store sensitive information such as client secrets.
Push the resulting directory to the remote Git repository.

Create a namespace for workloads

You must create a namespace for your workloads for the Workload resources to function properly. If you have a workloads namespace already, you can skip this step.

kubectl create namespace my-apps
kubectl label namespaces my-apps apps.tanzu.vmware.com/tap-ns=""

For more information about provisioning namespaces for running Workloads, see Set up developer namespaces.

Claim the client credentials

Follow these steps to claim the credentials for an Application Single Sign-On service so that you can secure your workload:

Discover the available Application Single Sign-On services with the Tanzu Service CLI:
```
$ tanzu service class list
  NAME      DESCRIPTION
  sso       Login by AppSSO
```
The actual names of your Application Single Sign-On services might be different. VMWare assumes that there’s one Application Single Sign-On service with the name sso.

Claim the credentials for that service by creating a ClassClaim named angular-frontend in the my-apps namespace.

---
apiVersion: services.apps.tanzu.vmware.com/v1alpha1
kind: ClassClaim
metadata:
  name: angular-frontend
  namespace: my-apps
spec:
  classRef:
    name: sso
  parameters:
    workloadRef:
      name: angular-frontend
    redirectPaths:
      - /user-profile
      - /customer-profiles/list
      - /
    scopes:
      - name: openid
      - name: email
      - name: profile
      - name: message.read
      - name: message.write
    authorizationGrantTypes:
      - authorization_code
    clientAuthenticationMethod: none

Apply the ClassClaim and verify the status is Ready by running:

kubectl get classclaim angular-frontend --namespace my-apps

Verify application authentication settings

Within the single-page Angular app accelerator, authentication configuration settings are located in src/assets/auth.conf.json. After generating the accelerator, expect to observe the populated settings.

Open the file and verify that it adheres to the following structure:

{
  "authority": "ISSUER-URI",
  "clientId": "CLIENT-ID",
  "scope": [ "openid", "profile", "email", "message.read", "message.write" ]
}

Retrieve your client id by running:

kubectl get secret \
  $(kubectl get classclaim -n my-apps angular-frontend -o jsonpath='{.status.binding.name}') \
  --namespace my-apps \
  --template='{{ index .data "client-id" | base64decode}}'

Retrieve your issuer URI by running:

kubectl get secret \
  $(kubectl get classclaim -n my-apps angular-frontend -o jsonpath='{.status.binding.name}') \
  --namespace my-apps \
  --template='{{ index .data "issuer-uri" | base64decode}}'

Start a sample back end

Important
You can skip this step if you have a java-rest-service back end running already.

The angular-frontend sample application requires a back end application to start properly:

Start a sample simulated back end by running:

kubectl run sample-backend --image nginx:NGINX-VERSION -n my-apps
kubectl expose pod sample-backend --port 80 -n my-apps

In the angular-frontend source code, edit the .server.location[/api/].proxy_pass field in the nginx.conf file at the root of the source directory.

After updating the value, commit the changes to the Git remote repository:

server {
 # ...
 location /api/ {
   proxy_pass http://sample-backend.my-apps/api/;
 }
 # ...
}

Deploy the `Workload`

Follow these steps to deploy the Workload:

Create the angular-frontend accelerator Workload by running:

tanzu apps workload create angular-frontend \
    --namespace my-apps \
    --type web \
    --param "clusterBuilder=base" \
    --param "annotations=autoscaling.knative.dev/minScale: \"1\"" \
    --label app.kubernetes.io/part-of=angular-frontend \
    --git-repo "GIT-LOCATION-OF-YOUR-ACCELERATOR" \
    --git-branch main

Note
As an alternative approach to creating the workload, you can declaratively define a Workload resource by using config/workload.yaml within the source repository.

It might take a few minutes for the workload to become available through a browser-accessible URL.

Query the latest status of the workload by running:

tanzu apps workload get angular-frontend --namespace my-apps

Monitor the Workload logs:
```
tanzu apps workload tail angular-frontend --namespace my-apps
```
After the status of the workload reaches the Ready state, you can navigate to the provided URL, which looks similar to:
```
https://angular-frontend.my-apps.TAP-CLUSTER-DOMAIN-NAME/user-profile
```
Open your preferred web browser and navigate to the URL.

Expect to be prompted to sign in by using AppSSO. After successfully signing in, the profile page displays your identifying information.

Clean up

Delete the running application by running these commands:

Delete the sample application Workload:

tanzu apps workload delete angular-frontend --namespace my-apps

Delete the claim:

tanzu service class-claims delete angular-frontend --namespace my-apps

Delete the sample back end if was previously applied:

kubectl delete svc sample-backend --namespace my-apps
kubectl delete pod sample-backend --namespace my-apps