K8s Native API Development

A single API in APK project is defined using a set of combined Kubernetes resources.

• API - With the API CRD, you can effortlessly design and manage APIs using Kubernetes-native tools. Simplify the deployment process and focus on what matters most – crafting outstanding APIs.This is the root level resource for an API. API related metadata are also defined in this CR.

• HTTPRoute - The HTTPRoute CRD empowers you to configure HTTP routes and filters for your APIs efficiently. You refer to HTTPRoute resources from API.

• Backend - Elevate your endpoint configurations, including resiliency settings, using the Backend CRD. Ensure the reliability and availability of your API backends for uninterrupted service.

These are the basic resource you need to use specifically for APK. We have other resources for complex use cases which are described under separate sections.

Let's create a simple API with following steps:

• Create API CR
• Create HTTPRoute CR
• Create Backend CR

Create API CR

In the following CR, we have defined a REST API giving the name, context, and version information for the API. We have also refers to HTTPRoute resource in spec.production.httpRouteRefs[0] path which we create in the next step.

apiVersion: dp.wso2.com/v1alpha1
kind: API
metadata:
  name: http-bin-api
spec:
  apiName: HTTP Bin API
  apiType: REST
  apiVersion: 1.0.0
  basePath: /http-bin-api/1.0.0
  production:
  - httpRouteRefs:
    - prod-http-route-http-bin-api

Info

If your API has many resources and cannot define within a single HTTPRoute resource, then you have to create two or more HTTPRoutes and list them under spec.production.httpRouteRefs.

Create HTTPRoute CR

This is the resource where you define resources of your API. This HTTPRoute is linked to the API by referring to this resource name from the API resource.

apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
metadata:
  name: prod-http-route-http-bin-api
spec:
  hostnames:
    - http-bin.gw.wso2.com
  parentRefs:
    - group: gateway.networking.k8s.io
      kind: Gateway
      name: default
      sectionName: httpslistener
  rules:
  - backendRefs:
    - group: dp.wso2.com
      kind: Backend
      name: http-bin-backend
    matches:
    - path:
        type: PathPrefix
        value: /http-bin-api/1.0.0
    filters:
      - type: URLRewrite
        urlRewrite:
          path:
            type: ReplacePrefixMatch
            replacePrefixMatch: /

Here, we have used http-bin.gw.wso2.com as the virtual hostname for this API. The spec.parentRefs[0] parameter defines the Gateway to which this HTTPRoute is deployed. We have defined a single rule with a PathPrefix match type, and the URLRewrite filter with ReplacePrefixMatch to rewrite the API context prefix so that only the remainder of the path is sent to the actual backend.

Create Backend CR

In the above created HTTPRoute resource we have referred to a Backend resource in spec.rules[0].backendRefs[0] path. That Backend should be created as below:

apiVersion: dp.wso2.com/v1alpha1
kind: Backend
metadata:
  name: http-bin-backend
spec:
  services:
  - host: httpbin.org
    port: 80

Here, we have set the httpbin.org domain name as the host with port 80, which is an insecure port. To make it a TLS-secured endpoint, refer to the Manage Certificate section.

If your backend is a Kubernetes-native Service, then derive the following value according to your Service and use it as the host.

<spec.metadata.name>.<spec.metadata.namespace>

Once you have designed your APIs using these essential CRDs, the next step is to apply them to the Kubernetes API server. APK will process and deploy your APIs seamlessly, taking full advantage of the Kubernetes infrastructure.

kubectl apply -f <path_to_CR_files>