How to consume on-prem services in public Node.JS API deployed on Cloud Foundry

[prashant9444]

Introduction

I wanted to create some public API with Node.JS which needs to deploy on Cloud foundry environment. In that I had to consume on-prem service. While consuming on-prem service in unauthenticate Node.JS app, throwing me error as Invaild Proxy Authorization Header. After lot of  search, I figure out the solution for it. So I'm thinking to write solution in one place.

In this blog post will explain you how to connect with on-prem services with Node.JS using XSUAA & Connectivity service instances.

 

Coding

1. Create package.json file & update with it below code
   

   {
   
     "name": "<APP_NAME>",
   
     "version": "1.0.0",
   
     "description": "",
   
     "main": "app.js",
   
     "scripts": {
   
       "test": "echo \"Error: no test specified\" && exit 1",
   
       "start": "node app.js"
   
     },
   
     "author": "Prashant Patil",
   
     "license": "ISC",
   
     "dependencies": {
   
       "@sap/xsenv": "^2.2.0",
   
       "body-parser": "^1.19.0",
   
       "express": "^4.16.4",
   
       "request": "^2.88.0",
   
       "request-promise": "^4.2.5"
   
     }
   
   }
   
   ​

   
   


2. Create manifest.yml file & update with below code
   

   ---
   
   applications:
   
   - name: test-app
   
     memory: 128M
   
     instances: 1
   
     services:
   
       - test-app-uaa
   
       - test-app-conn
   
       ​

   
   


3. Create service instances mentioned in manifest.yml using CF CLI
   

   cf create-service xsuaa application test-app-uaa​

   
   

   cf create-service connectivity lite test-app-conn​

   
   


4. Create app.js & paste below code, We are going connect to the on-prem service through connectivity service instance.
   

   const express = require('express');
   
   const rp = require('request-promise');
   
   const xsenv = require('@sap/xsenv');
   
   
   
   //For local run
   
   //xsenv.loadEnv();
   
   
   
   const http = require('http');
   
   var bodyParser = require('body-parser');
   
   const app = express();
   
   var server = http.createServer(app);
   
   const port = process.env.PORT || 3000;
   
   var jsonParser = bodyParser.json();
   
   var urlencodedParser = bodyParser.urlencoded({ extended: false });
   
   
   
   const conn_service = xsenv.getServices({ conn: { tag: 'connectivity' } }).conn;
   
   const uaa_service = xsenv.getServices({ uaa: { tag: 'xsuaa' } }).uaa;
   
   const sUaaCredentials = conn_service.clientid + ':' + conn_service.clientsecret;
   
   const proxy_url = 'http://'+conn_service["onpremise_proxy_host"] + ':' + conn_service["onpremise_proxy_port"];
   
   const onPremCred = '<OnpremSrvUser>:<OnpremSrvUserPassword>';
   
   
   
   server.listen(port, () => console.log(`test app listening at http://localhost:${port}`));
   
   
   
   app.post('/getDetailsFromOnPrem',jsonParser , (req, res) => {
   
       return rp({
   
           uri: uaa_service.url + '/oauth/token',
   
           method: 'POST',
   
           headers: {
   
               'Authorization': 'Basic ' + Buffer.from(sUaaCredentials).toString('base64'),
   
               'Content-type': 'application/x-www-form-urlencoded'
   
           },
   
           form: {
   
               'client_id': conn_service.clientid,
   
               'grant_type': 'client_credentials'
   
           }
   
       }).then((data) => {
   
           const token = JSON.parse(data).access_token;
   
           
   
           return rp({
   
               uri: '<on-prem service url>',
   
               proxy:proxy_url,
   
               headers : {
   
                   'Authorization': 'Basic ' + Buffer.from(onPremCred).toString('base64'),
   
                   'Proxy-Authorization': 'Bearer ' + token,
   
                   'SAP-Connectivity-SCC-Location_ID':'<Cloud-Connector-Location-Id>',
   
                   'Content-type': 'application/json'
   
               }
   
           });
   
       }).then((data) => {
   
           const d = JSON.parse(data);
   
           res.send(d);
   
           
   
       }).catch((error) => {
   
           res.send(error);
   
   });​

   
   


5. Deploy app to CF
   

   cf push test-app​

   
   

 

Note:

if you have only one connector without location Id (default) in your sub-account, then do not provide 'SAP-Connectivity-SCC-Location_ID' as header.

If you have multiple Cloud connectors added in your sub-account then 'SAP-Connectivity-SCC-Location_ID'  header is must else it will trying connect with default cloud connector.

Conclusion

In this blog post you learned how to consume on-premise services in unauthenticated Node.JS app deployed on CF.

 

Hope this helps!

 

 

Prashant Patil