Gateway API support

The Gateway API is a set of CRDs in the gateway.networking.k8s.io API group which describe types of traffic in a way that is independent of a specific mesh or ingress implementation. Recent versions of Linkerd fully support the Kubernetes Gateway API as a core configuration mechanism, and many Linkerd features, including authorization policies, dynamic traffic routing, and request timeouts, rely on resource types from the Gateway API for configuration.

The two primary Gateway API types used to configure Linkerd are:

• HTTPRoute, which parameterizes HTTP requests
• GRPCRoute, which parameterizes gRPC requests

Both of these types are used in a variety of ways when configuring Linkerd.

Managing the Gateway API

One complication with using the Gateway API in practice is that many different packages, not just Linkerd, may provide the Gateway API on your cluster, but only some Gateway API versions are compatible with Linkerd.

In practice, there are two basic approaches to managing the Gateway API with Linkerd. You can let Linkerd manage the Gateway API resources, or you can let a different tool manage them.

Option 1: Linkerd manages the Gateway API

This is the default behavior for Linkerd, which will create, update, and delete Gateway API resources as required. In this approach, any other tools on your system that use Gateway API resources will be need to be compatible with the version of the Gateway API that Linkerd installs:

Option 2: A different tool manages the Gateway API

Alternatively, you may prefer to have something other than Linkerd manage the Gateway API resources on your cluster. To do this, you will need to instruct Linkerd not to install, update, or delete the Gateway API resources, by passing pass the --set enableHttpRoutes=false flag during the linkerd install --crds step, or setting the enableHttpRoutes=false Helm value when installing the linkerd-crds Helm chart.

You will also need to ensure that version of the Gateway API installed is compatible with Linkerd:

If possible, you should install the recommended Gateway API version in the table above. (Note that the use of experimental Gateway API versions is sometimes necessary to allow for full functionality; despite the name, these versions are production capable.)

Precursors to Gateway API-based configuration

Prior to the complete support of the Gateway API introduced in Linkerd 2.14, Linkerd provided two earlier variants of configuration:

• A Linkerd-specific HTTPRoute CRD provided by Linkerd in the policy.linkerd.io API group
• ServiceProfiles, which allowed for configuration of per-route metrics, retries, and timeouts prior to the introduction of the Gateway API types.

Both of these earlier configuration mechanisms continue to be supported; however, newer feature development is focused on the standard Gateway API types.

Learn More

To get started with the Gateway API types, you can:

• Configure fault injection
• Configure timeouts
• Configure dynamic request routing
• Configure per-route authorization policy