Basic Authentication Policy

Through this task, you will learn how to:

  • Use authentication policy to setup mutual TLS.

  • Use authentication policy to do end-user authentication.

Before you begin

  • Understand Istio authentication policy and related mutual TLS authentication concepts.

  • Have a Kubernetes cluster with Istio installed, without global mutual TLS enabled (e.g use install/kubernetes/istio-demo.yaml as described in installation steps, or set global.mtls.enabled to false using Helm).

  • For demo, create two namespaces foo and bar, and deploy httpbin and sleep with sidecar on both of them. Also, run another sleep app without sidecar (to keep it separate, run it in legacy namespace)

    $ kubectl create ns foo
    $ kubectl apply -f <(istioctl kube-inject -f @samples/httpbin/httpbin.yaml@) -n foo
    $ kubectl apply -f <(istioctl kube-inject -f @samples/sleep/sleep.yaml@) -n foo
    $ kubectl create ns bar
    $ kubectl apply -f <(istioctl kube-inject -f @samples/httpbin/httpbin.yaml@) -n bar
    $ kubectl apply -f <(istioctl kube-inject -f @samples/sleep/sleep.yaml@) -n bar
    $ kubectl create ns legacy
    $ kubectl apply -f @samples/sleep/sleep.yaml@ -n legacy
    
  • Verifying setup by sending an http request (using curl command) from any sleep pod (among those in namespace foo, bar or legacy) to either httpbin.foo or httpbin.bar. All requests should success with HTTP code 200.

    For example, here is a command to check sleep.bar to httpbin.foo reachability:

    $ kubectl exec $(kubectl get pod -l app=sleep -n bar -o jsonpath={.items..metadata.name}) -c sleep -n bar -- curl http://httpbin.foo:8000/ip -s -o /dev/null -w "%{http_code}\n"
    200
    

    Conveniently, this one-liner command iterates through all combinations:

    $ for from in "foo" "bar" "legacy"; do for to in "foo" "bar"; do kubectl exec $(kubectl get pod -l app=sleep -n ${from} -o jsonpath={.items..metadata.name}) -c sleep -n ${from} -- curl http://httpbin.${to}:8000/ip -s -o /dev/null -w "sleep.${from} to httpbin.${to}: %{http_code}\n"; done; done
    sleep.foo to httpbin.foo: 200
    sleep.foo to httpbin.bar: 200
    sleep.bar to httpbin.foo: 200
    sleep.bar to httpbin.bar: 200
    sleep.legacy to httpbin.foo: 200
    sleep.legacy to httpbin.bar: 200
    
  • Also verify that there are no authentication policy in the system

    $ kubectl get policies.authentication.istio.io --all-namespaces
    No resources found.
    

Enable mutual TLS for all services in a namespace

Run this command to set namespace-level policy for namespace foo.

cat <<EOF | istioctl create -f -
apiVersion: "authentication.istio.io/v1alpha1"
kind: "Policy"
metadata:
  name: "example-1"
  namespace: "foo"
spec:
  peers:
  - mtls:
EOF

And verify the policy was added:

$ kubectl get policies.authentication.istio.io -n foo
NAME        AGE
example-1   1m

Add this destination rule to configure client side to use mutual TLS:

cat <<EOF | istioctl create -f -
apiVersion: "networking.istio.io/v1alpha3"
kind: "DestinationRule"
metadata:
  name: "example-1"
  namespace: "foo"
spec:
  host: "*.foo.svc.cluster.local"
  trafficPolicy:
    tls:
      mode: ISTIO_MUTUAL
EOF

Note: * This rule is based on the assumption that there is no other destination rule in the system. If it’s not the case, you need to modify traffic policy in existing rules accordingly. * *.foo.svc.cluster.local matches all services in namespace foo. * With ISTIO_MUTUAL TLS mode, Istio will set the path for key and certificates (e.g clientCertificate, privateKey and caCertificates) according to its internal implementation.

Run the same testing command as above. You should see requests from sleep.legacy to httpbin.foo start to fail, as the result of enabling mutual TLS for httpbin.foo but sleep.legacy doesn’t have a sidecar to support it. On the other hand, for clients with sidecar (sleep.foo and sleep.bar), Istio automatically configures them to using mutual TLS where talking to http.foo, so they continue to work. Also, requests to httpbin.bar are not affected as the policy is only effective on the foo namespace.

$ for from in "foo" "bar" "legacy"; do for to in "foo" "bar"; do kubectl exec $(kubectl get pod -l app=sleep -n ${from} -o jsonpath={.items..metadata.name}) -c sleep -n ${from} -- curl http://httpbin.${to}:8000/ip -s -o /dev/null -w "sleep.${from} to httpbin.${to}: %{http_code}\n"; done; done
sleep.foo to httpbin.foo: 200
sleep.foo to httpbin.bar: 200
sleep.bar to httpbin.foo: 200
sleep.bar to httpbin.bar: 200
sleep.legacy to httpbin.foo: 000
command terminated with exit code 56
sleep.legacy to httpbin.bar: 200

If destination rule above is not created, all requests to httpbin.foo will fail as client side are not configured correctly to switch to use mutual TLS.

Enable mutual TLS for single service httpbin.bar

Run this command to set another policy only for httpbin.bar service. Note in this example, we do not specify namespace in metadata but put it in the command line (-n bar). They should work the same.

cat <<EOF | istioctl create -n bar -f -
apiVersion: "authentication.istio.io/v1alpha1"
kind: "Policy"
metadata:
  name: "example-2"
spec:
  targets:
  - name: httpbin
  peers:
  - mtls:
EOF

And a destination rule:

cat <<EOF | istioctl create -n bar -f -
apiVersion: "networking.istio.io/v1alpha3"
kind: "DestinationRule"
metadata:
  name: "example-2"
spec:
  host: "httpbin.bar.svc.cluster.local"
  trafficPolicy:
    tls:
      mode: ISTIO_MUTUAL
EOF

Again, run the probing command. As expected, request from sleep.legacy to httpbin.bar starts failing with the same reasons.

...
sleep.legacy to httpbin.bar: 000
command terminated with exit code 56

If we have more services in namespace bar, we should see traffic to them won’t be affected. Instead of adding more services to demonstrate this behavior, we edit the policy slightly:

cat <<EOF | istioctl replace -n bar -f -
apiVersion: "authentication.istio.io/v1alpha1"
kind: "Policy"
metadata:
  name: "example-2"
spec:
  targets:
  - name: httpbin
    ports:
    - number: 1234
  peers:
  - mtls:
EOF

And a corresponding change to the destination rule:

cat <<EOF | istioctl replace -n bar -f -
apiVersion: "networking.istio.io/v1alpha3"
kind: "DestinationRule"
metadata:
  name: "example-2"
spec:
  host: httpbin.bar.svc.cluster.local
  trafficPolicy:
    tls:
      mode: DISABLE
    portLevelSettings:
    - port:
        number: 1234
      tls:
        mode: ISTIO_MUTUAL
EOF

This new policy will apply only to the httpbin service on port 1234. As a result, mutual TLS is disabled (again) on port 8000 and requests from sleep.legacy will resume working.

$ kubectl exec $(kubectl get pod -l app=sleep -n legacy -o jsonpath={.items..metadata.name}) -c sleep -n legacy -- curl http://httpbin.bar:8000/ip -s -o /dev/null -w "%{http_code}\n"
200

Having both namespace-level and service-level policies

Assuming we already added the namespace-level policy that enables mutual TLS for all services in namespace foo and observe that request from sleep.legacy to httpbin.foo are failing (see above). Now add another policy that disables mutual TLS (peers section is empty) specifically for the httpbin service:

cat <<EOF | istioctl create -n foo -f -
apiVersion: "authentication.istio.io/v1alpha1"
kind: "Policy"
metadata:
  name: "example-3"
spec:
  targets:
  - name: httpbin
EOF

and destination rule:

cat <<EOF | istioctl create -n foo -f -
apiVersion: "networking.istio.io/v1alpha3"
kind: "DestinationRule"
metadata:
  name: "example-3"
spec:
  host: httpbin.foo.svc.cluster.local
  trafficPolicy:
    tls:
      mode: DISABLE
EOF

Re-run the request from sleep.legacy, we should see a success return code again (200), confirming service-level policy overrules the namespace-level policy.

$ kubectl exec $(kubectl get pod -l app=sleep -n legacy -o jsonpath={.items..metadata.name}) -c sleep -n legacy -- curl http://httpbin.foo:8000/ip -s -o /dev/null -w "%{http_code}\n"
200

Setup end-user authentication

You will need a valid JWT (corresponding to the JWKS endpoint you want to use for the demo). Please follow the instructions here to create one. You can also use your own JWT/JWKS endpoint for the demo. Once you have that, export to some environment variables.

$ export SVC_ACCOUNT="example@my-project.iam.gserviceaccount.com"
$ export JWKS=https://www.googleapis.com/service_accounts/v1/jwk/${SVC_ACCOUNT}
$ export TOKEN=<YOUR-TOKEN>

Also, for convenience, expose httpbin.foo via ingress (for more details, see ingress task).

cat <<EOF | kubectl apply -f -
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: httpbin-ingress
  namespace: foo
  annotations:
    kubernetes.io/ingress.class: istio
spec:
  rules:
  - http:
      paths:
      - path: /headers
        backend:
          serviceName: httpbin
          servicePort: 8000
EOF

Get ingress IP

export INGRESS_HOST=$(kubectl get ing -n foo -o=jsonpath='{.items[0].status.loadBalancer.ingress[0].ip}')

And run a test query

$ curl $INGRESS_HOST/headers -s -o /dev/null -w "%{http_code}\n"
200

Now, let’s add a policy that requires end-user JWT for httpbin.foo. The next command assumes policy with name “httpbin” already exists (which should be if you follow previous sections). You can run kubectl get policies.authentication.istio.io -n foo to confirm, and use istio create (instead of istio replace) if resource is not found. Also note in this policy, peer authentication (mutual TLS) is also set, though it can be removed without affecting origin authentication settings.

cat <<EOF | istioctl replace -n foo -f -
apiVersion: "authentication.istio.io/v1alpha1"
kind: "Policy"
metadata:
  name: "example-3"
spec:
  targets:
  - name: httpbin
  peers:
  - mtls:
  origins:
  - jwt:
      issuer: $SVC_ACCOUNT
      jwksUri: $JWKS
  principalBinding: USE_ORIGIN
EOF

The same curl command from before will return with 401 error code, as a result of server is expecting JWT but none was provided:

$ curl $INGRESS_HOST/headers -s -o /dev/null -w "%{http_code}\n"
401

Attaching the valid token generated above returns success:

$ curl --header "Authorization: Bearer $TOKEN" $INGRESS_HOST/headers -s -o /dev/null -w "%{http_code}\n"
200

You may want to try to modify token or policy (e.g change issuer, audiences, expiry date etc) to observe other aspects of JWT validation.

Cleanup

Remove all resources.

$ kubectl delete ns foo bar legacy

What’s next