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Knative Serving architecture

Knative Serving on OpenShift Container Platform enables developers to write cloud-native applications using serverless architecture. Serverless is a cloud computing model where application developers don’t need to provision servers or manage scaling for their applications. These routine tasks are abstracted away by the platform, allowing developers to push code to production much faster than in traditional models.

Knative Serving supports deploying and managing cloud-native applications by providing a set of objects as Kubernetes custom resource definitions (CRDs) that define and control the behavior of serverless workloads on an OpenShift Container Platform cluster. For more information about CRDs, see Extending the Kubernetes API with custom resource definitions.

Developers use these CRDs to create custom resource (CR) instances that can be used as building blocks to address complex use cases. For example:

  • Rapidly deploying serverless containers.

  • Automatically scaling pods.

For more information about CRs, see Managing resources from custom resource definitions.

Knative Serving CRDs

Service

The service.serving.knative.dev CRD automatically manages the life cycle of your workload to ensure that the application is deployed and reachable through the network. It creates a route, a configuration, and a new revision for each change to a user created service, or CR. Most developer interactions in Knative are carried out by modifying services.

Revision

The revision.serving.knative.dev CRD is a point-in-time snapshot of the code and configuration for each modification made to the workload. Revisions are immutable objects and can be retained for as long as necessary.

Route

The route.serving.knative.dev CRD maps a network endpoint to one or more revisions. You can manage the traffic in several ways, including fractional traffic and named routes.

Configuration

The configuration.serving.knative.dev CRD maintains the desired state for your deployment. It provides a clean separation between code and configuration. Modifying a configuration creates a new revision.