API Curation (alpha)

This topic tells you how to use API Curation to expose several standalone APIs as one API for API Auto Registration.

Caution
The API Curation feature is in alpha and is intended for evaluation and test purposes only. VMware discourages using API Curation in a production environment.

Overview

To unlock the maximum power of API curation, VMware recommends using a supported route provider. Without this a supported route provider, the generated API specifications do not have a functional server URL set for testing the curated API. You must manually create the routing resources to route traffic to each referenced API to match with the aggregated API specifications. With the route provider integration, these routing concerns are taken care of automatically.

Prerequisites

A successful API curation requires the following prerequisites:

(Optional) Spring Cloud Gateway for Kubernetes is installed.
(Optional) SpringCloudGateway resources created with the matching groupId and version.
One or more APIDescriptors in the ready state.
Create a CuratedAPIDescriptor resource referencing ready APIDescriptors.

You can get the aggregated API specifications from the OpenAPI endpoint from the controller.

(Optional) Install route provider and create gateway resources

You can optionally install a route provider and create gateway resources.

Setup Spring Cloud Gateway integration

Using Spring Cloud Gateway for Kubernetes (SCG) integration as a route provider is optional. To install SCG, see Install Spring Cloud Gateway for Kubernetes.

For SCG v2.1.0 and later, if you enabled TLS on SCG, or installed it in a custom namespace, you must overwrite route_provider.spring_cloud_gateway.scg_openapi_service_url in your API Auto Registration values file.

route_provider:
  spring_cloud_gateway:
    scg_openapi_service_url: "http://scg-openapi-service.spring-cloud-gateway.svc.cluster.local" # default value

If you are using an earlier version of SCG, consider upgrading or see the following table to understand the impact:

Capability with SCG v2.1.0 and later	Behavior before SCG v2.1.0
The default value `scg_openapi_service_url` is sufficient if using the default SCG installation	You must overwrite the value `scg_openapi_service_url` with `http://scg-operator.tap-install.svc.cluster.local` if using the default SCG installation.
Matching SCG updates API metadata automatically and the generated OpenAPI specifications reflect the metadata	API metadata annotations are added or updated, but the API specifications exposed from SCG OpenAPI endpoint do not reflect that

Create SpringCloudGateway resource

You can create, using GitOps or manually, an SpringCloudGateway CR and apply it in the cluster you choose.

The following is an example SCG resource:

apiVersion: "tanzu.vmware.com/v1"
kind: SpringCloudGateway
metadata:
  name: test-api-curation
spec:
  api:
    version: 1.2.3
    groupId: test-api-curation
    serverUrl: https://my-curated-api.mydomain.com
    cors:
      allowedOrigins:
        - "http://api-portal.mydomain.com"
      allowedMethods:
        - "GET"
        - "PUT"
        - "POST"
      allowedHeaders:
        - '*'

The groupId and version matches on SCG when it reconciles for CuratedAPIDescriptor. After finding a match, SCG uses serverUrl as the baseURL of the curated API.

Create APIDescriptors for curation

To create APIDescriptor resources, see API Auto Registration Usage Guide. If any of the referenced APIDescriptor are not ready, the CuratedAPIDescriptor keeps retrying until all the referenced APIDescriptors are ready. If the API specifications from any of the APIDescriptor update, the controller selects the changes on the next reconciliation loop.

Note
By default, the update might take up to 10 minutes, including maximum 5 minutes to refresh the APIDescriptor, and maximum 5 minutes to refresh CuratedAPIDescriptor. You can shorten the wait time by configuring sync_period in the AAR values file.

Create CuratedAPIDescriptor custom resource

Using your GitOps process, or manually, you can create an CuratedAPIDescriptor CR and apply it in the cluster you choose. Specify all the required fields for an CuratedAPIDescriptor CR to reconcile.

For information about CuratedAPIDescriptors, see CuratedAPIDescriptor explained.

You can view the readiness of the applied CuratedAPIDescriptors by running:

kubectl get curatedapidescriptors -A

NAMESPACE           NAME         GROUPID            VERSION   STATUS   CURATED API SPEC URL
my-apps             petstore     cute-api-group     1.2.3     Ready    http://AAR-CONTROLLER-FQDN/openapi/my-apps/petstore

Retrieve curated API specifications

The API Auto Registration controller offers an endpoint to retrieve all of the generated API specifications for the curated APIs in the cluster.

To retrieve curated API specifications:

Find the HTTPProxy that’s created to access the endpoint:

kubectl get httpproxy api-auto-registration-controller -n api-auto-registration

The following is an example output:

NAME                               FQDN                              TLS SECRET                   STATUS   STATUS DESCRIPTION
api-auto-registration-controller   api-auto-registration.tap.domain  api-auto-registration-cert   valid    Valid HTTPProxy

To get all the curated API specifications with curl, use FQDN with an http scheme:
```
curl http(s)://AAR-CONTROLLER-FQDN/openapi
```
Where AAR-CONTROLLER-FQDN is the AAR FQDN controller you want the specifications for.
Retrieve specifications for CuratedAPIDescriptor from a specific namespace by specifying the following path:
```
curl http(s)://AAR-CONTROLLER-FQDN/openapi/NAMESPACE
```
Where NAMESPACE is the namespace that you want to retrieve specifications from.
Retrieve specifications for a specific CuratedAPIDescriptor by namespace and name:
```
curl http(s)://AAR-CONTROLLER-FQDN/openapi/NAMESPACE/NAME
```
Where:
- NAMESPACE is the namespace of the CuratedAPIDescriptor that you want to use.
- NAME is name of the CuratedAPIDescriptor that you want to use.
Retrieve specifications for a specific groupId and version combination by specifying query parameters:
```
curl http(s)://AAR-CONTROLLER-FQDN/openapi?groupId=GROUP-ID&version=VERSION
curl http(s)://AAR-CONTROLLER-FQDN/openapi/NAMESPACE?groupId=GROUP-ID&version=VERSION
```
Where:
- NAMESPACE is the namespace that you want to retrieve specifications from.
- VERSION is the version you want the specifications for.
- GROUP-ID is group ID you want the specifications for.
- AAR-CONTROLLER-FQDN is the AAR-CONTROLLER-FQDN you want to query.
Add the curated APIs to an API portal for display by configuring the source URL locations of an existing API portal. You can add all your curated APIs by using the unfiltered URL http(s)://AAR-CONTROLLER-FQDN/openapi or the filtered URL with query parameters to add a specific curated API of your choice. See Configuring API portal for VMware Tanzu on Kubernetes.
This curated API is not automatically registered in Tanzu Developer Portal. You can do this manually by creating an api.yaml and adding it to the catalog. For information about the structure of the definition file for an API entity, see the API documentation plug-in in Tanzu Developer Portal or the Backstage Kind: API documentation.