(Optional) Exercise 3: Authorization with Istio

This is an optional lab, run through it if time permits.

Besides authentication using mTLS, Istio can also provide authorization services:

  • End-user to workload

  • Workload to workload

The end-user to workload authentication we handle in our example in the application code itself, you will learn about it in the last section of our workshop (Application security with Keycloak and Quarkus).

In this exercise we will learn how to apply authorization policies to further secure communication within the service mesh, workload to workload. In our example we will use Kubernetes Service Accounts to perform the authorization.

Review the existing deployment

When you create a pod, if you do not specify a service account, it is automatically assigned the default service account in the same namespace. You can check this for the articles service:

STEP 1: Get the full name of the articles pod from the resulting list:

kubectl get pods

Example output:

NAME READY STATUS RESTARTS AGE
articles-xxxxxxxxxx-yyyyy 2/2 Running 0 3d23h
keycloak-77cffb978-nbmjj 2/2 Running 0 3d23h
web-api-5c9698b875-c8vrt 2/2 Running 0 3d23h
web-app-79499c4b99-dv2hs 2/2 Running 0 3d23h

STEP 2: Now display the details for the pod in YAML format and search for the term serviceAccount:

kubectl get pod articles-xxxxxxxxxx-yyyyy -o json | grep serviceAccount

Result:

"serviceAccount": "default",
"serviceAccountName": "default",

The articles pod indeed uses the default service account.

Modify deployments to use service accounts

Step 1: First we create 2 service accounts (sa) for our 2 services

kubectl create sa articles
kubectl create sa web-api

Note: The image shows you in the Kubernetes Dashboard the two new service accounts. This is not a part of your hands-on tasks.

Step 2: Then we replace the deployment descriptions to use the service accounts we just created:

kubectl replace -f $ROOT_FOLDER/articles-secure/deployment/articles-sa.yaml
kubectl replace -f $ROOT_FOLDER/web-api-secure/deployment/web-api-sa.yaml

Step 3: This will recreate the articles and web-api pods. Check with:

kubectl get pods
kubectl get pod articles-xxxxxxxxxx-yyyyy -o json | grep serviceAccount

Result:

"serviceAccount": "articles",
"serviceAccountName": "articles"

If you test the application in the browser it should work exactly the same as before.

Authorization Policy

Step 1: Verify the authorization policy

First we apply an incomplete authorization policy to the articles service. It looks like this:

apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
name: articlesaccess
spec:
selector:
matchLabels:
app: articles
action: ALLOW

Istio documentation specifies: If any allow policies are applied to a workload, access to that workload is denied by default, unless explicitly allowed by the rule in the policy.

We have an "ALLOW" policy but no rule is specified which makes it effectively a "DENY ALL" rule.

Step 2: Apply with rule

kubectl apply -f $ROOT_FOLDER/IKS/authorization.yaml

Step 3: Check the application in the browser again. It may take a while for the policy to propagate to the Envoy but eventually you will see this error in the browser:

Example output:

Articles could not be read
Error: Request failed with status code 500

Step 4: Verify AuthorizationPolicy

Now we use a correct authorization poliy. It looks like this:

apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
name: articlesaccess
spec:
selector:
matchLabels:
app: articles
action: ALLOW
rules:
- from:
- source:
principals: ["cluster.local/ns/default/sa/web-api"]
to:
- operation:
methods: ["GET", "POST"]

It allows GET and POST access to the articles service for the service account (sa) web-api in namespace (ns) default.

Step 5: Apply rule

Apply with:

kubectl apply -f $ROOT_FOLDER/IKS/authorization-w-rule.yaml

Step 5: Verify the access

Check the application in the browser again. It may take a while for the policy to propagate to the Envoy but eventually you will see that the application works.

Now we using Istio and Keycloak at the same time.

Note: The image shows you in Kiali there is AuthorizationPolicy defined This is not a part of your hands-on tasks.

Optional: Setup telemetry to inspect dependencies of the Microservices in Kiali

"Kiali is an observability console for Istio with service mesh configuration capabilities. It helps you to understand the structure of your service mesh by inferring the topology, and also provides the health of your mesh."

  1. Execute following script to setup telemetry

cd $ROOT_FOLDER/IKS
bash istio-setup-telemetry.sh
  1. Open a second IBM Cloud Shell terminal session

  2. Execute the port-forward command in the new terminal session:

    kubectl port-forward svc/kiali 3000:20001 -n istio-system

    Result should indicate forwarding from port 3000 to port 20001.

  3. Click on the "Eye" icon in the upper right corner of Cloud Shell and select port 3000.

    port forward

    This will open a new browser tab with the Kiali dashboard.

  4. Log in with admin/admin.

  5. Open the Graph tab, in Namespaces select all namespaces and in display ensure you have selectedsecurity`

    kiali

This graph shows the components of your microservices architecture. Explore the other tabs.

Congratulations, you have successfully completed this optional lab and you did the extra mile for Platform security with mTLS section of the workshop. Awesome :star: