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Use API Auto Registration

This topic describes how to use API Auto Registration.

Note The run profile requires you to update the install values before proceeding. For iterate and full profiles, the default values work but you might prefer to update them. For information about profiles, see About Tanzu Application Platform profiles.

API Auto Registration requires the following:

  1. A location exposing a dynamic or static API specification.

  2. An APIDescriptor Custom Resource (CR) with that location created in the cluster.

  3. (Optional) Configure Cross-Origin Resource Sharing (CORS) for OpenAPI specifications.

To generate OpenAPI Spec:

To create APIDescriptor Custom Resource:

To configure:

Generate OpenAPI Spec

Using a Spring Boot app with a REST service

You can use a Spring Boot example app built using Building a RESTful Web Service guide. and has the Springdoc dependency.

Example of a workload using the Spring Boot app:

apiVersion: carto.run/v1alpha1
kind: Workload
metadata:
  name: simple-rest-app
  labels:
    ...
    apis.apps.tanzu.vmware.com/register-api: "true"
spec:
  source:
    ...
  params:
    - name: api_descriptor
      value:
        type: openapi
        location:
          path: "/v3/api-docs"
        system: dev
        owner: team-a
        description: "A set of API endpoints."

Using App Accelerator Template

If you are creating a new application exposing an API, you might use the java-rest-service App Accelerator template to get a pre-built app that includes a workload.yaml with a basic REST API. From your Tanzu Application Platform GUI Accelerators tab, search for the accelerator and scaffold it according to your needs.

Using an existing Spring Boot project using springdoc

If you have an existing Spring Boot app that exposes an API, you can generate OpenAPI specifications using springdoc. See the springdoc documentation

After you have springdoc configured and an OpenAPI automatically generated, you can choose one of the three methods of creating the APIDescriptor custom resource. VMware recommends having your Spring Boot app to be managed using Workloads and the Out-Of-The-Box (OOTB) supply chain. See the Use Out-Of-The-Box (OOTB) supply chains for further instructions. Alternatively, if you want to use custom supply chains, see Using Custom Supply Chains. Lastly, if you want to use a different Gitops process or manage the APIDescriptor CR manually, see the Using other GitOps processes or Manually section.

Create APIDescriptor Custom Resource

Use Out-Of-The-Box (OOTB) supply chains

All the Out-Of-The-Box (OOTB) supply chains are modified so that they can use API Auto Registration. If you want your workload to be auto registered, you must make modifications to your workload YAML:

  1. Add the label apis.apps.tanzu.vmware.com/register-api: "true".

  2. Add a parameter of type api_descriptor:

      params:
    - name: api_descriptor
      value:
        type: openapi   # We currently support any of openapi, aysncapi, graphql, grpc
        location:
          path: "/v3/api-docs"  # The path to the api documentation
        owner: team-petclinic   # The team that owns this
        description: "A set of API endpoints to manage the resources within the petclinic app."

There are 2 different options for the location:

  • The default supply chains use Knative to deploy your applications. In this event the only location information you must send is the path to the API documentation. The controller can figure out the base URL for you.
  • You can hardcode the URL using the baseURL property. The controller uses a combination of this baseURL and your path to retrieve the YAML.

Example workload that exposes a Knative service:

apiVersion: carto.run/v1alpha1
kind: Workload
metadata:
  name: petclinic-knative
  labels:
    ...
    apis.apps.tanzu.vmware.com/register-api: "true"
spec:
  source:
    ...
  params:
    - name: api_descriptor
      value:
        type: openapi
        location:
          path: "/v3/api-docs"
        system: pet-clinics
        owner: team-petclinic
        description: "A set of API endpoints to manage the resources within the petclinic app."

Example of a workload with a hardcoded URL to the API documentation:

apiVersion: carto.run/v1alpha1
kind: Workload
metadata:
  name: petclinic-hard-coded
  labels:
    ...
    apis.apps.tanzu.vmware.com/register-api: "true"
spec:
  source:
    ...
  params:
    - name: api_descriptor
      value:
        type: openapi
        location:
          baseURL: http://petclinic-hard-coded.my-apps.tapdemo.vmware.com/
          path: "/v3/api-docs"
        owner: team-petclinic
        system: pet-clinics
        description: "A set of API endpoints to manage the resources within the petclinic app."

After the supply chain runs, it creates an APIDescriptor custom resource. This resource is what Tanzu Application Platform uses to auto register your API. See APIDescriptor explained.

Using Custom Supply Chains

If you are creating custom supply chains, you can still use API Auto Registration. To write a supply chain pipeline, use ClusterConfigTemplate by the name of config-template in your pipeline. To write a custom task, verify how the template is written to read parameters, interpret baseURL from Knative Services, and construct APIDescriptor CRs.

In the Delivery pipeline, you must directly create an APIDescriptor custom resource. You must grant permissions to create the CR from the delivery pipeline.

For information about APIDescriptors, see Key Concepts.

Using other GitOps processes or Manually

Using your GitOps process, or manually, you must stamp out an APIDescriptor CR and apply it in the cluster you choose. Be sure specify all the required fields for an APIDescriptor CR to reconcile.

For information about APIDescriptors, see Key Concepts.

Additional configuration

Setting up CORS for OpenAPI specifications

The agent, usually a browser, uses the CORS protocol to verify whether the current origin uses an API. To use the "Try it out" feature for OpenAPI specifications from the API Documentation plug-in, you must configure CORS to allow successful requests.

Your API must be configured to allow CORS Requests from Tanzu Application Platform GUI. How you accomplish this varies based on the programming language and framework you are using. If you are using Spring, see CORS support in spring framework.

At a high level, the Tanzu Application Platform GUI domain must be accepted as valid cross-origin by your API.

Verify the following:

  • Origins allowed header: Access-Control-Allow-Origin: A list of comma-separated values. This list must include your Tanzu Application Platform GUI host.
  • Methods allowed header: Access-Control-Allow-Method: Must allow the method used by your API. Also confirm that your API supports preflight requests, a valid response to the OPTIONS HTTP method.
  • Headers allowed header: Access-Control-Allow-Headers: If the API requires any header, you must include it in the API configuration or your authorization server.