82 lines
3.7 KiB
Markdown
82 lines
3.7 KiB
Markdown
---
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title: "Pinniped Architecture"
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cascade:
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layout: docs
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---
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# Architecture
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The principal purpose of Pinniped is to allow users to access Kubernetes
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clusters. Pinniped hopes to enable this access across a wide range of Kubernetes
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environments with zero configuration.
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This integration is implemented using a credential exchange API which takes as
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input a credential from the external IDP and returns a credential which is understood by the host
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Kubernetes cluster.
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Pinniped supports various IDP types and implements different integration strategies
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for various Kubernetes distributions to make authentication possible.
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## Supported Kubernetes Cluster Types
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Pinniped supports the following types of Kubernetes clusters:
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- Clusters where the Kube Controller Manager pod is accessible from Pinniped's pods.
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Support for other types of Kubernetes distributions is coming soon.
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## External Identity Provider Integrations
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Pinniped will consume identity from one or more external identity providers
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(IDPs). Administrators will configure external IDPs via Kubernetes custom
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resources allowing Pinniped to be managed using GitOps and standard Kubernetes tools.
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Pinniped supports the following external IDP types.
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1. Any webhook which implements the
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[Kubernetes TokenReview API](https://kubernetes.io/docs/reference/access-authn-authz/authentication/#webhook-token-authentication).
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In addition to allowing the integration of any existing IDP which implements this API, webhooks also
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serve as an extension point for Pinniped by allowing for integration of arbitrary custom authenticators.
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While a custom implementation may be in any language or framework, this project provides a
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sample implementation in Golang. See the `ServeHTTP` method of
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[cmd/local-user-authenticator/main.go](https://github.com/vmware-tanzu/pinniped/cmd/local-user-authenticator/main.go).
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More IDP types are coming soon.
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## Cluster Integration Strategies
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Pinniped will issue a cluster credential by leveraging cluster-specific
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functionality. In the near term, cluster integrations will happen via different
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cluster-specific flows depending on the type of cluster. In the longer term,
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Pinniped hopes to contribute and leverage upstream Kubernetes extension points that
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cleanly enable this integration.
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Pinniped supports the following cluster integration strategies.
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* Pinniped hosts a credential exchange API endpoint via a Kubernetes aggregated API server.
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This API returns a new cluster-specific credential using the cluster's signing keypair to
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issue short-lived cluster certificates. (In the future, when the Kubernetes CSR API
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provides a way to issue short-lived certificates, then the Pinniped credential exchange API
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will use that instead of using the cluster's signing keypair.)
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More cluster integration strategies are coming soon, which will allow Pinniped to
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support more Kubernetes cluster types.
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## kubectl Integration
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With any of the above IDPs and integration strategies, `kubectl` commands receive the
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cluster-specific credential via a
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[Kubernetes client-go credential plugin](https://kubernetes.io/docs/reference/access-authn-authz/authentication/#client-go-credential-plugins).
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Users may use the Pinniped CLI as the credential plugin, or they may use any proprietary CLI
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built with the [Pinniped Go client library](https://github.com/vmware-tanzu/pinniped/generated).
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## Example Cluster Authentication Sequence Diagram
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This diagram demonstrates using `kubectl get pods` with the Pinniped CLI configured as the credential plugin,
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and with a webhook IDP configured as the identity provider for the Pinniped server.
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