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