Securing the Kubeflow authentication with HTTPS

How to secure the Kubeflow authentication with HTTPS using the network load balancer

This guide describes how to secure the Kubeflow authentication with HTTPS. You can enable HTTPS for Kubeflow dashboard (and other web UIs) using the network load balancer (NLB) feature of the IBM Cloud Kubernetes service—choose the classic worker nodes provider in the Setting environment variables section of the Create an IBM Cloud cluster guide.

Note: For details on NLB, go to the official Classic: About network load balancers guide.

Prerequisites

Install and configure the IBM Cloud CLI.
Install multi-user, auth-enabled Kubeflow.

Setting up an NLB

To set up an NLB for your Kubernetes cluster, follow the official Classic: Setting up basic load balancing with an NLB 1.0 guide. Notice that the setup process for a multi-zone cluster differs from that of a single-zone cluster. For details, go to Setting up an NLB 1.0 in a multi-zone cluster.

To use the existing Istio ingress gateway (instead of creating a new service), you need to update the service type of istio-ingressgateway to LoadBalancer from NodePort. Run the following command:
```
kubectl patch svc istio-ingressgateway -n istio-system -p '{"spec":{"type":"LoadBalancer"}}'
```
Verify that the NLB was created successfully. It might take a few minutes for the service to be created and an IP address to be made available. Run the command below and check if you can see the LoadBalancer Ingress IP address:
```
kubectl describe service istio-ingressgateway -n istio-system | grep "LoadBalancer Ingress"
```

Store the external IP of the istio-ingressgateway service in an environment variable:

export INGRESS_GATEWAY_IP=$(kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.status.loadBalancer.ingress[0].ip}')

Exposing the Kubeflow dashboard with DNS and TLS termination

The following instructions use the Kubeflow dashboard as an example. However, they apply to other web UI applications, since they all go through the Istio ingress gateway.

Store the Kubernetes cluster name in an environment variable by running the following command:
```
export CLUSTER_NAME=<cluster_name>
```

Create a DNS domain and certificates for the IP of the service istio-ingressgateway in namespace istio-system:

ibmcloud ks nlb-dns create classic --cluster $CLUSTER_NAME --ip $INGRESS_GATEWAY_IP --secret-namespace istio-system

List the registered domain names:

ibmcloud ks nlb-dns ls --cluster $CLUSTER_NAME

Wait until the status of the certificate—the fourth field—of the new domain name becomes created. Then, save the value of the column SSL Cert Secret Name in environment variables by running these commands (replace {SECRET_NAME} with the secret’s name as shown in the SSL Cert Secret Name column):
```
export INGRESS_GATEWAY_SECRET={SECRET_NAME}
```
Note: If there is more than one entry in the output, choose the one that matches the IP address from LoadBalancer Ingress (step 2) of service istio-ingressgateway.

Create a secret named istio-ingressgateway-certs for the istio-ingressgateway pods in namespace istio-system:

kubectl get secret $INGRESS_GATEWAY_SECRET -n istio-system -o yaml > istio-ingressgateway-certs.yaml

Update the istio-ingressgateway-certs.yaml file by changing the value of metadata.name to istio-ingressgateway-certs and the value of metadata.namespace to istio-system. Then, run the following commands:
```
kubectl apply -f istio-ingressgateway-certs.yaml -n istio-system
kubectl rollout restart deploy istio-ingressgateway -n istio-system
rm istio-ingressgateway-certs.yaml
```

Update the gateway kubeflow-gateway to expose port 443. Create a resource file kubeflow-gateway.yaml as follows by replacing <hostname> with the value of the column Hostname in step 4:

apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: kubeflow-gateway
  namespace: kubeflow
spec:
  selector:
    istio: ingressgateway
  servers:
  - hosts:
    - '<hostname>'
    port:
      name: https
      number: 443
      protocol: HTTPS
    tls:
      mode: SIMPLE
      privateKey: /etc/istio/ingressgateway-certs/tls.key
      serverCertificate: /etc/istio/ingressgateway-certs/tls.crt

Verify that the traffic is routed via HTTPS by using the value of above-mentioned Hostname in your browser. It should redirect traffic from an HTTP address to HTTPS address automatically.

Note: The certificates for the NLB DNS host secret expire every 90 days. The secret in the default namespace is automatically renewed by IBM Cloud Kubernetes Service 37 days before it expires. After this secret is updated, you must manually copy it to the istio-ingressgateway-certs secret by repeating commands in step 5 and 6.

Optional - KFServing configuration

With this HTTPS setup, you need to make additional changes to get KFServing to work.

First, update the Knative domain that is used for the KFServing routes to the hostname that you used when updating kubeflow-gateway.

kubectl edit configmap config-domain -n knative-serving

This will open your default text editor, and you will see something like:

apiVersion: v1
data:
  _example: |
    ################################
    #                              #
    #    EXAMPLE CONFIGURATION     #
    #                              #
    ################################
    # ...
    example.com: |    
kind: ConfigMap
...

Add a line above the _example key with your hostname as the key and an empty string value. Be sure to update <hostname>:

apiVersion: v1
data:
  <hostname>: ""
  _example: |
      ...
kind: ConfigMap
...

Then, save and exit. The routes for your InferenceServices will start using this new domain.

Since the certificates provided by IBM Cloud only allow for a single level of domain name added to the base domain, the domain template for Knative needs to be adjusted so that the certificates will be valid for the InferenceService routes.
```
kubectl edit configmap config-network -n knative-serving
```
This will open your default text editor, and you will again see something like:
```
apiVersion: v1
data:
  _example: |
    ################################
    #                              #
    #    EXAMPLE CONFIGURATION     #
    #                              #
    ################################
    # ...    
kind: ConfigMap
...
```
Add a line above the _example key with the domainTemplate key like the following:
```
apiVersion: v1
data:
  domainTemplate: "{{.Name}}-{{.Namespace}}.{{.Domain}}"
  _example: |
      ...
kind: ConfigMap
...
```
Save and exit. The default template uses a two-level subdomain (i.e. {{.Name}}.{{.Namespace}}.{{.Domain}}), so this just adjusts it to use one.

Adjust kubeflow-gateway one more time, adding a wildcard host in the HTTPS hosts section.

kubectl edit gateway kubeflow-gateway -n kubeflow

This will open your default text editor, but you can also optionally edit kubeflow-gateway.yaml file you created previously. Here, just add another entry to the HTTPS hosts list containing your hostname prepended with a *. so that the Knative subdomains are properly routed.

apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: kubeflow-gateway
  namespace: kubeflow
spec:
  selector:
    istio: ingressgateway
  servers:
  - hosts:
    - '<hostname>'
    - '*.<hostname>'
    port:
      name: https
      number: 443
      protocol: HTTPS
    tls:
      mode: SIMPLE
      privateKey: /etc/istio/ingressgateway-certs/tls.key
      serverCertificate: /etc/istio/ingressgateway-certs/tls.crt

Save and exit.

After these adjustments, InferenceServices should now be reachable via HTTPS. To test out an external prediction, you can use the authservice_session cookie for the Kubeflow dashboard site from the browser. Once the content of the cookie is retrieved from the browser, it can be added as a header in your request (e.g. "Cookie: authservice_session=MTYwNz..."). For example:

curl -v https://sklearn-iris-kfserving-test.kf-dev-442dbba0442be6c8c50f31ed96b00532-0001.sjc03.containers.appdomain.cloud/v1/models/sklearn-iris:predict -d '{"instances": [[6.8,  2.8,  4.8,  1.4],[6.0,  3.4,  4.5,  1.6]]}' -H "Cookie: authservice_session=MTYwODMyODk5M3xOd3dBTkVzeU5VSlJRazlQVnpWT1dGUldWa0ZXVDBRMVFsY3pVVFZHVVVGV01rWkRORmd6VmxCVVNsQkVSa2xaUlZVMFRUVldVMEU9fJBHfRCAvs6nSh_J04VlBEq_yqhkUvc5Z1Mqahe9klOd"

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Last modified 29.04.2021: Iks 1.3 docs (#2660) (d9820156)