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Configure the Pinniped Supervisor as an OIDC issuer

The Supervisor is an OpenID Connect (OIDC) issuer that supports connecting a single “upstream” identity provider to many “downstream” cluster clients. When a user authenticates, the Supervisor can issue JSON Web Tokens (JWTs) that can be validated by the Pinniped Concierge.

This guide explains how to expose the Supervisor’s REST endpoints to clients.

Prerequisites

This how-to guide assumes that you have already installed the Pinniped Supervisor.

Exposing the Supervisor app’s endpoints outside the cluster

The Supervisor app’s endpoints should be exposed as HTTPS endpoints with proper TLS certificates signed by a certificate authority (CA) which is trusted by your end user’s web browsers.

It is recommended that the traffic to these endpoints should be encrypted via TLS all the way into the Supervisor pods, even when crossing boundaries that are entirely inside the Kubernetes cluster. The credentials and tokens that are handled by these endpoints are too sensitive to transmit without encryption.

In previous versions of the Supervisor app, there were both HTTP and HTTPS ports available for use by default. These ports each host all the Supervisor’s endpoints. Unfortunately, this has caused some confusion in the community and some blog posts have been written which demonstrate using the HTTP port in such a way that a portion of the traffic’s path is unencrypted. Newer versions of the Supervisor disable the HTTP port by default to make it more clear that the Supervisor app is not intended to receive non-TLS HTTP traffic from outside the Pod. Furthermore, in these newer versions, when the HTTP listener is configured to be enabled it may only listen on loopback interfaces for traffic from within its own pod. To aid in transition for impacted users, the old behavior of allowing the HTTP listener to receive traffic from outside the pod may be re-enabled using the deprecated_insecure_accept_external_unencrypted_http_requests value in values.yaml, until that setting is removed in a future release.

Because there are many ways to expose TLS services from a Kubernetes cluster, the Supervisor app leaves this up to the user. The most common ways are:

  • Define a TCP LoadBalancer Service.

    In this case, the Service is a layer 4 load balancer which does not terminate TLS, so the Supervisor app needs to be configured with TLS certificates and will terminate the TLS connection itself (see the section about FederationDomain below). The LoadBalancer Service should be configured to use the HTTPS port 443 of the Supervisor pods as its targetPort.

  • Or, define an Ingress resource.

    In this case, the Ingress typically terminates TLS and then talks plain HTTP to its backend. However, because the Supervisor’s endpoints deal with sensitive credentials, the ingress must be configured to re-encrypt traffic using TLS on the backend (upstream) into the Supervisor’s Pods. It would not be secure for the OIDC protocol to use HTTP, because the user’s secret OIDC tokens would be transmitted across the network without encryption. If your Ingress controller does not support this feature, then consider using one of the other configurations described here instead of using an Ingress. (Please refer to the paragraph above regarding the deprecation of the HTTP listener for more information.) The backend of the Ingress would typically point to a NodePort or LoadBalancer Service which exposes the HTTPS port 8443 of the Supervisor pods.

    The required configuration of the Ingress is specific to your cluster’s Ingress Controller, so please refer to the documentation from your Kubernetes provider. If you are using a cluster from a cloud provider, then you’ll probably want to start with that provider’s documentation. For example, if your cluster is a Google GKE cluster, refer to the GKE documentation for Ingress and the GKE documentation for enabling TLS on the backend of an Ingress. Otherwise, the Kubernetes documentation provides a list of popular Ingress Controllers, including Contour and many others. Contour is an example of an ingress implementation which supports TLS on the backend, along with TLS session proxying and TLS session pass-through as alternative ways to maintain TLS all the way to the backend service.

  • Or, expose the Supervisor app using a Kubernetes service mesh technology (e.g. Istio).

    In this case, the setup would be similar to the previous description for defining an Ingress, except the service mesh would probably provide both the ingress with TLS termination and the service. Please see the documentation for your service mesh.

    If your service mesh is capable of transparently encrypting traffic all the way into the Supervisor Pods, then you should use that capability. In this case, it may make sense to configure the Supervisor’s HTTP port to listen on a Unix domain socket, such as when the service mesh injects a sidecar container that can securely access the socket from within the same Pod. Alternatively, the HTTP port can be configured as a TCP listener on loopback interfaces to receive traffic from sidecar containers. See the endpoints option in deploy/supervisor/values.yml for more information. Using either a Unix domain socket or a loopback interface listener would prevent any unencrypted traffic from accidentally being transmitted from outside the Pod into the Supervisor app’s HTTP port.

    For example, the following high level steps cover configuring Istio for use with the Supervisor:

    • Update the HTTP listener to use a Unix domain socket i.e. --data-value-yaml 'endpoints={"http":{"network":"unix","address":"/pinniped_socket/socketfile.sock"}}'
    • Arrange for the Istio sidecar to be injected into the Supervisor app with an appropriate IstioIngressListener i.e defaultEndpoint: unix:///pinniped_socket/socketfile.sock
    • Mount the socket volume into the Istio sidecar container by including the appropriate annotation on the Supervisor pods i.e. sidecar.istio.io/userVolumeMount: '{"socket":{"mountPath":"/pinniped_socket"}}'
    • Disable the HTTPS listener and update the deployment health checks as desired

    For service meshes that do not support Unix domain sockets, the HTTP listener should be configured as a TCP listener on a loopback interface.

Creating a Service to expose the Supervisor app’s endpoints within the cluster

Now that you’ve selected a strategy to expose the endpoints outside the cluster, you can choose how to expose the endpoints inside the cluster in support of that strategy.

If you’ve decided to use a LoadBalancer Service then you’ll need to create it. On the other hand, if you’ve decided to use an Ingress then you’ll need to create a Service which the Ingress can use as its backend. Either way, how you create the Service will depend on how you choose to install the Supervisor:

  • If you installed using ytt then you can use the related service_* options from deploy/supervisor/values.yml to create a Service.
  • If you installed using the pre-rendered manifests attached to the Pinniped GitHub releases, then you can create the Service separately after installing the Supervisor app.

There is no Ingress included in either the ytt templates or the pre-rendered manifests, so if you choose to use an Ingress then you’ll need to create the Ingress separately after installing the Supervisor app.

Example: Creating a LoadBalancer Service

This is an example of creating a LoadBalancer Service to expose port 8443 of the Supervisor app outside the cluster.

apiVersion: v1
kind: Service
metadata:
  name: pinniped-supervisor-loadbalancer
  # Assuming that this is the namespace where the Supervisor was installed.
  # This is the default.
  namespace: pinniped-supervisor
spec:
  type: LoadBalancer
  selector:
    # Assuming that this is how the Supervisor Pods are labeled.
    # This is the default.
    app: pinniped-supervisor
  ports:
  - protocol: TCP
    port: 443
    targetPort: 8443 # 8443 is the TLS port.

Example: Creating a NodePort Service

A NodePort Service exposes the app as a port on the nodes of the cluster. For example, a NodePort Service could also be used as the backend of an Ingress.

This is also convenient for use with Kind clusters, because kind can expose node ports as localhost ports on the host machine without requiring an Ingress, although Kind also supports several Ingress Controllers.

apiVersion: v1
kind: Service
metadata:
  name: pinniped-supervisor-nodeport
  # Assuming that this is the namespace where the Supervisor was installed.
  # This is the default.
  namespace: pinniped-supervisor
spec:
  type: NodePort
  selector:
    # Assuming that this is how the Supervisor Pods are labeled.
    # This is the default.
    app: pinniped-supervisor
  ports:
  - protocol: TCP
    port: 443
    targetPort: 8443
    # This is the port that you would forward to the kind host.
    # Or omit this key for a random port on the node.
    nodePort: 31234

Configuring the Supervisor to act as an OIDC provider

The Supervisor can be configured as an OIDC provider by creating FederationDomain resources in the same namespace where the Supervisor app was installed. At least one FederationDomain must be configured for the Supervisor to provide its functionality.

Here is an example of a FederationDomain.

apiVersion: config.supervisor.pinniped.dev/v1alpha1
kind: FederationDomain
metadata:
  name: my-provider
  # Assuming that this is the namespace where the supervisor was installed.
  # This is the default.
  namespace: pinniped-supervisor
spec:
  # The hostname would typically match the DNS name of the public ingress
  # or load balancer for the cluster.
  # Any path can be specified, which allows a single hostname to have
  # multiple different issuers. The path is optional.
  issuer: https://my-issuer.example.com/any/path
  # Optionally configure the name of a Secret in the same namespace,
  # of type `kubernetes.io/tls`, which contains the TLS serving certificate
  # for the HTTPS endpoints served by this OIDC Provider.
  tls:
    secretName: my-tls-cert-secret

You can create multiple FederationDomains as long as each has a unique issuer string. Each FederationDomain can be used to provide access to a set of Kubernetes clusters for a set of user identities.

Configuring TLS for the Supervisor OIDC endpoints

If you have terminated TLS outside the app, for example using service mesh which handles encrypting the traffic for you, then you do not need to configure TLS certificates on the FederationDomain. Otherwise, you need to configure the Supervisor app to terminate TLS.

There are two places to optionally configure TLS certificates:

  1. Each FederationDomain can be configured with TLS certificates, using the spec.tls.secretName field.

  2. The default TLS certificate for all FederationDomains can be configured by creating a Secret called pinniped-supervisor-default-tls-certificate in the same namespace in which the Supervisor was installed.

Each incoming request to the endpoints of the Supervisor may use TLS certificates that were configured in either of the above ways. The TLS certificate to present to the client is selected dynamically for each request using Server Name Indication (SNI):

  • When incoming requests use SNI to specify a hostname, and that hostname matches the hostname of a FederationDomain, and that FederationDomain specifies spec.tls.secretName, then the TLS certificate from the spec.tls.secretName Secret will be used.
  • Any other request will use the default TLS certificate, if it is specified. This includes any request to a host which is an IP address, because SNI does not work for IP addresses. If the default TLS certificate is not specified, then these requests will fail TLS certificate verification.

It is recommended that you have a DNS entry for your load balancer or Ingress, and that you configure the OIDC provider’s issuer using that DNS hostname, and that the TLS certificate for that provider also covers that same hostname.

You can create the certificate Secrets however you like, for example you could use cert-manager or kubectl create secret tls. They must be Secrets of type kubernetes.io/tls. Keep in mind that your end users must load some of these endpoints in their web browsers, so the TLS certificates should be signed by a certificate authority that is trusted by their browsers.

Next steps

Next, configure an OIDCIdentityProvider, ActiveDirectoryIdentityProvider, or an LDAPIdentityProvider for the Supervisor (several examples are available in these guides), and configure the Concierge to use the Supervisor for authentication on each cluster!