OpenShift Serverless provides Kubernetes native building blocks that enable developers to create and deploy serverless, event-driven applications on OpenShift Container Platform. OpenShift Serverless is based on the open source Knative project, which provides portability and consistency for hybrid and multi-cloud environments by enabling an enterprise-grade serverless platform.
Because OpenShift Serverless releases on a different cadence from OpenShift Container Platform, the OpenShift Serverless documentation does not maintain separate documentation sets for minor versions of the product. The current documentation set applies to all currently supported versions of OpenShift Serverless unless version-specific limitations are called out in a particular topic or for a particular feature.
For additional information about the OpenShift Serverless life cycle and supported platforms, refer to the Platform Life Cycle Policy.
Knative Serving supports developers who want to create, deploy, and manage cloud-native applications. It provides 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.
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.
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 custom resource. Most developer interactions in Knative are carried out by modifying services.
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.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.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.
Knative Eventing on OpenShift Container Platform enables developers to use an event-driven architecture with serverless applications. An event-driven architecture is based on the concept of decoupled relationships between event producers and event consumers.
Event producers create events, and event sinks, or consumers, receive events. Knative Eventing uses standard HTTP POST requests to send and receive events between event producers and sinks. These events conform to the CloudEvents specifications, which enables creating, parsing, sending, and receiving events in any programming language.
Knative Eventing supports the following use cases:
You can send events to a broker as an HTTP POST, and use binding to decouple the destination configuration from your application that produces events.
You can use a trigger to consume events from a broker based on event attributes. The application receives events as an HTTP POST.
To enable delivery to multiple types of sinks, Knative Eventing defines the following generic interfaces that can be implemented by multiple Kubernetes resources:
Able to receive and acknowledge an event delivered over HTTP to an address defined in the
status.address.url field of the event. The Kubernetes
Service resource also satisfies the addressable interface.
Able to receive an event delivered over HTTP and transform it, returning
1 new events in the HTTP response payload. These returned events may be further processed in the same way that events from an external event source are processed.
You can propagate an event from an event source to multiple event sinks by using:
The set of supported features, configurations, and integrations for OpenShift Serverless, current and past versions, are available at the Supported Configurations page.
OpenShift Serverless has been tested with a configuration of 3 main nodes and 3 worker nodes, each of which has 64 CPUs, 457 GB of memory, and 394 GB of storage each.
The maximum number of Knative services that can be created using this configuration is 3,000. This corresponds to the OpenShift Container Platform Kubernetes services limit of 10,000, since 1 Knative service creates 3 Kubernetes services.
The average scale from zero response time was approximately 3.4 seconds, with a maximum response time of 8 seconds, and a 99.9th percentile of 4.5 seconds for a simple Quarkus application. These times might vary depending on the application and the runtime of the application.