sap-java-buildpack-api-usage

Description

This sample uses the SAP application router as a web server and forwards requests to a Java back-end application running on the SAP Java buildpack. In a typcal UI5 application, the application router server HTML files and REST data would be provided by a back-end application. To focus on the security part, UI5 has been omitted.

Coding

The web.xml of the application must use auth-method with value XSUAA. This enables authentication of requests using incoming OAuth authentication tokens.

<web-app>
<display-name>sample</display-name>
  <login-config> 
    <auth-method>XSUAA</auth-method>
  </login-config> 
</web-app> 

In the Java coding, use the @ServletSecurity annotations:

package com.sap.cloud.security.xssec.samples.sapbuildpack;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.HttpConstraint;
import javax.servlet.annotation.ServletSecurity;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.sap.xsa.security.container.XSUserInfo;
import com.sap.xsa.security.container.XSUserInfoException;

/**
 * Servlet implementation class HelloTokenServlet
 */
@WebServlet("/hello-token")

// configure servlet to check against scope "$XSAPPNAME.Display"
@ServletSecurity(@HttpConstraint(rolesAllowed = { "Display" }))
public class HelloTokenServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/plain");
		XSUserInfo userInfo = (XSUserInfo) request.getUserPrincipal();

		try {
			response.getWriter().append("Client ID: ").append("" + userInfo.getClientId());
			response.getWriter().append("\n");
			response.getWriter().append("Email: ").append("" + userInfo.getEmail());
			response.getWriter().append("\n");
			response.getWriter().append("Family Name: ").append("" + userInfo.getFamilyName());
			response.getWriter().append("\n");
			response.getWriter().append("First Name: ").append("" + userInfo.getGivenName());
			response.getWriter().append("\n");
			response.getWriter().append("OAuth Grant Type: ").append("" + userInfo.getGrantType());
			response.getWriter().append("\n");
			response.getWriter().append("OAuth Token: ").append("" + userInfo.getAppToken());
			response.getWriter().append("\n");

		} catch (XSUserInfoException e) {
			e.printStackTrace(response.getWriter());
		}
	}
}

Deployment on Cloud Foundry

To deploy the application, the following steps are required:

• Configure the Application Router
• Compile the Java application
• Create a xsuaa service instance
• Configure the manifest
• Deploy the application git
• Access the application

Configure the Application Router

The Application Router is used to provide a single entry point to a business application that consists of several different apps (microservices). It dispatches requests to backend microservices and acts as a reverse proxy. The rules that determine which request should be forwarded to which destinations are called routes. The application router can be configured to authenticate the users and propagate the user information. Finally, the application router can serve static content.

Compile the Java application

Run maven to package the application

mvn clean package

Create the xsuaa service instance

Use the xs-security.json to define the authentication settings and create a service instance

cf create-service xsuaa application xsuaa-buildpack -c xs-security.json

Configuration the manifest

The vars contains hosts and paths that need to be adopted.

Deploy the application

Deploy the application using cf push. It will expect 1 GB of free memory quota.

cf push --vars-file ../vars.yml

Cockpit administration tasks: Assign Role to your User

Finally, as part of your Identity Provider, e.g. SAP ID Service, assign the deployed Role Collection(s) such as Buildpack_API_Viewer to your user as depicted in the screenshot below and as documented here.

Further up-to-date information you can get on sap.help.com:

• Maintain Role Collections
• Maintain Roles for Applications.

Access the application

After deployment, the application router will trigger authentication. If you have assigned the role-collection provided in the xs-security.json to your user, you will see an output like when calling https://approuter-sap-java-buildpack-api-usage-<<ID>>.<<LANDSCAPE_APPS_DOMAIN>>:

Client ID: sap-java-buildpack-api-usage!t5721
Email: user@mail
Family Name: Jones
First Name: Bob
OAuth Grant Type: authorization_code
OAuth Token: eyJhbGciOiJSUzI1NiIsInR5...

If not you should get a 403 status code (Forbidden).

Note: you can find the route of your approuter application using cf app approuter-sap-java-buildpack-api-usage.

Clean-Up

Finally delete your application and your service instances using the following commands:

cf delete -f sap-java-buildpack-api-usage
cf delete -f approuter-sap-java-buildpack-api-usage
cf delete-service -f xsuaa-buildpack