SAP CAP: Consume SAP API Hub Sandbox Data as an external service Part- 2

[DebashishDas]

What: 

This blog post is about consuming external services from BTP after deploying your service/application. This is the continuation of the previous post Part- 1.

Here we are going to deploy and access the same external service from the cloud foundry

How:

Deploying Application

Now we are going to deploy our CAP project in SCP Cloud Foundry

Before deploying using the command, we need to build the project.

$ cds build/all

Create mta.yaml file by using the below command.

$ cds add mta

MTA file will look like below –

---

_schema-version: '3.1'

ID: BusinessPartner

version: 1.0.0

description: "A simple CAP project."

parameters:

  enable-parallel-deployments: true

build-parameters:

  before-all:

    - builder: custom

      commands:

        - npm ci

        - npx -p @sap/cds-dk cds build --production



modules:

  - name: BusinessPartner-srv

    type: nodejs

    path: gen/srv

    parameters:

      buildpack: nodejs_buildpack

    build-parameters:

      builder: npm-ci

    provides:

      - name: srv-api # required by consumers of CAP services (e.g. approuter)

        properties:

          srv-url: ${default-url}

As this file does not hold enough information to run the application in the Cloud foundry, We need two resources binding with our service application to up and running in CF.

1. Destination service


2. xsuaa service

Let create the Destination service in BTP

Login to your account and search for destination under service marketplace.

Click on create Button and provide the Instance name. In my case, I have created demo-destination instance.

Service: Destination Service

Plan: lite

Runtime Environment: Cloud Foundry

Space: dev

Instance Name: demo-destination

Click on demo-destination instance and configure a new destination

URL=https://sandbox.api.sap.com/s4hanacloud/sap/opu/odata/sap/API_BUSINESS_PARTNER/

Name=API_BUSINESS_PARTNER

ProxyType=Internet

Type=HTTP

Authentication=NoAuthentication

Description=Business Partner SandBox API

Now we have created one service instance for our application. Let's create xs-security.json for uaa service instance.

Run the below command

$ cds compile srv/ --to xsuaa > xs-security.json

We have to update our MTA file to make binding these two services with our application

---

_schema-version: '3.1'

ID: BusinessPartner

version: 1.0.0

description: "A simple CAP project."

parameters:

  enable-parallel-deployments: true

build-parameters:

  before-all:

    - builder: custom

      commands:

        - npm ci

        - npx -p @sap/cds-dk cds build --production

modules:

  - name: BusinessPartner-srv

    type: nodejs

    path: gen/srv

    parameters:

      buildpack: nodejs_buildpack

    build-parameters:

      builder: npm-ci

    provides:

      - name: srv-api # required by consumers of CAP services (e.g. approuter)

        properties:

          srv-url: ${default-url}

    requires:

      - name: demo-destination

      - name: businesspartner-uaa

      

resources:

 - name: demo-destination

   type: org.cloudfoundry.existing-service

   parameters:

     service-name: demo-destination



 - name: businesspartner-uaa

   type: org.cloudfoundry.managed-service

   parameters:

     path: ./xs-security.json

     service: xsuaa

     service-plan: application 

     config:

        xsappname: businesspartner-${org}-${space}

        tenant-mode: dedicated

We have to change the credentials to access the destination service in the package.json file.

"cds": {

        "requires": {

            "API_BUSINESS_PARTNER": {

                "kind": "odata-v2",

                "model": "srv/external/API_BUSINESS_PARTNER",

                "[development]": {

                    "credentials": {

                        "url": "https://sandbox.api.sap.com/s4hanacloud/sap/opu/odata/sap/API_BUSINESS_PARTNER",

                        "headers": {

                            "APIKey": "<api-key>"

                        }

                    }

                },

                "[production]": {

                    "credentials": {

                        "destination": "API_BUSINESS_PARTNER"

                    }

                }

            },

            "uaa": {

                "kind": "xsuaa"

            }

        }

    }

When you are going to access sandbox data for your local development you have to use "[development]" credentials.

Follow the below commands to deploy your cap project -

$ cds build/all

$ mbt build -t ./

$ cf deploy BusinessPartner_1.0.0.mtar

BusinessPartner_1.0.0.mtar, is generated after your MBT build command.

Now check in the BTP under the application section. The application has been deployed and it is has been Started.

Click on the application URL.

Click on A_BusinessPartner

Oops!! It was working fine in our BAS.

The reason is we are not passing APIkey to access the sandbox data. In package.json file we pass only destination name inside "[production]", not the apikey.

There are two ways I found how to use API key for the production environment.

1. Set the apikey in as an environment variable and use it in your code. In every request send it in as a header request.


2. We can modify the destination configuration in our destination service.

Here I am we are going to follow the second approach.

Open the destination service and an additional parameter

URL.headers.apiKey - <api-key>

 

Now again click on A_BusinessPartner

 

Response is coming from the API hub sandbox.

Now you know how to access API Hub sandbox data from a cap application

 

 

NOTE on 3rd December 2022: 

If you follow this blog you need to lower the version "@sap/cds": "^5" in package.json file. 

Or,

If use the latest version. follow the steps below -

Package dependencies -

  "dependencies": {

    "@sap-cloud-sdk/http-client": "^2.12.0",

    "@sap-cloud-sdk/util": "^2.12.0",

    "@sap/cds": "^6",

    "@sap/xsenv": "^3.4.0",

    "@sap/xssec": "^3.2.14",

    "express": "^4",

    "passport": "^0.6.0"

  },

 

Add authorisation on service -

service BusinessService @(requires: 'authenticated-user'){  

    @cds.autoexpose

    entity A_BusinessPartner as projection on abp.A_BusinessPartner {        

        key BusinessPartner, Customer, BusinessPartnerFullName, BusinessPartnerGrouping, BusinessPartnerUUID, OrganizationBPName1 

    }

}

 

Add the below parameters in xs-security.json -

{

  "scopes": [],

  "attributes": [],

  "role-templates": [],

  "authorities-inheritance": false,

  "oauth2-configuration": {

    "redirect-uris": [

      "https://*.hana.ondemand.com/**"

    ]

  }

}

 

Add approuter.

command - cds add approuter.

This will update the mta.yaml file and files files will be created corresponding to the approuter. A new module will be created. this is basically used for routing.

  - name: BusinessPartner

    type: approuter.nodejs

    path: app/ # from cds.env.folders. Consider also cds.env.build.target -> gen/app

    parameters:

      keep-existing-routes: true

      disk-quota: 256M

      memory: 256M

    requires:

      - name: srv-api

        group: destinations

        properties:

          name: srv-api # must be used in xs-app.json as well

          url: ~{srv-url}

          forwardAuthToken: true

      - name: BusinessPartner-xsuaa

 

Build and deploy the latest changes. Now one new Application will be created in your dev space. Execute "BusinessPartner". This will retrieve all the data like before.