Authenticate and Call the Azure Resource Manager (ARM) REST API from Java - Service to Service Authentication

Hello-Azure-ARM-Rest-API-ServiceToService.java

package javaapplication1;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.List;

// https://hc.apache.org/
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

// https://www.java2s.com/Code/JarDownload/java/java-json.jar.zip
import org.json.*;

/**
 *
 * @author demouser
 */
public class JavaApplication1 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException, JSONException, Exception {
        String tenantId = "azure-ad-tenant-id"; // Azure AD Tenant ID
        String subscriptionId = "azure-subscription-id"; // Azure Subscription ID
        String appId = "azure-ad-application-id"; // Application ID
        String appKey = "azure-ad-application-key"; // Application Key
        
        HttpClient httpclient = HttpClients.createDefault();
        
        System.out.println("Getting Acess Token from Azure AD...");
        
        try {
            URIBuilder authTokenBuilder = new URIBuilder(
                    "https://login.microsoftonline.com/" + tenantId + "/oauth2/token"
            );
            
            /*
            References:
            https://docs.microsoft.com/en-us/rest/api/azure/#create-the-request
            https://docs.microsoft.com/en-us/rest/api/azure/#register-your-client-application-with-azure-ad
            https://docs.microsoft.com/en-us/azure/active-directory/develop/active-directory-application-objects
            https://docs.microsoft.com/en-us/azure/azure-resource-manager/resource-group-create-service-principal-portal
            */
            
            // setup HttpPost request
            URI authTokenUri = authTokenBuilder.build();
            HttpPost authTokenRequest = new HttpPost(authTokenUri);
            
            // add required query parameterss
            List <NameValuePair> authTokenParams = new ArrayList <NameValuePair>();
            authTokenParams.add(new BasicNameValuePair("grant_type", "client_credentials"));
            authTokenParams.add(new BasicNameValuePair("client_id", appId));
            authTokenParams.add(new BasicNameValuePair("client_secret", appKey));
            authTokenParams.add(new BasicNameValuePair("resource", "https://management.core.windows.net")); //https://graph.windows.net"));
            authTokenRequest.setEntity(new UrlEncodedFormEntity(authTokenParams));
            
            HttpResponse authTokenResponse = httpclient.execute(authTokenRequest);
            HttpEntity authTokenEntity = authTokenResponse.getEntity();
            if (authTokenEntity == null) {
                    throw new Exception("authTokenEntity is null");
            }
            
            
            
            String authTokenJsonRaw = EntityUtils.toString(authTokenEntity);
            System.out.println("Raw JSON: " + authTokenJsonRaw);
            System.out.println("");            
            
            // parse out Access Token from JSON
            JSONObject authTokenJson = new JSONObject(authTokenJsonRaw);
            
            if (authTokenJson.has("error")) {
                System.out.println("ERROR RECEIVED: " + authTokenJson.getString("error"));
                System.out.println(authTokenJson.getString("error_description"));
                return;
            }
            
            String access_token = authTokenJson.getString("access_token");
            
            // Output values from the Response JSON to the terminal
            System.out.println("access_token: " + access_token);
            System.out.println("token_type: " + authTokenJson.getString("token_type"));
            System.out.println("expires_in: " + authTokenJson.getString("expires_in"));


            
            
            
            URIBuilder builder = new URIBuilder("https://management.azure.com/subscriptions/" + subscriptionId + "/resourcegroups");
            builder.setParameter("api-version", "2018-02-01");
            URI uri = builder.build();
            HttpGet request = new HttpGet(uri);
            request.addHeader("Authorization", "Bearer " + access_token);
            
            System.out.println("Get All Resource Groups in Azure Subscription...");
            HttpResponse response = httpclient.execute(request);
            
            System.out.println("HTTP Status Code: " + response.getStatusLine());
            
            HttpEntity entity = response.getEntity();
            String json = "";
            if (entity != null){
                json = EntityUtils.toString(entity);
                System.out.println("JSON: " + json);
                System.out.println("");
                
                // Output list of Resource Groups to console
                JSONObject parsedJson = new JSONObject(json);
                JSONArray resourceGroups = parsedJson.getJSONArray("value");
                for(int i = 0; i < resourceGroups.length(); i++){
                    JSONObject group = resourceGroups.getJSONObject(i);
                    System.out.println("Reource Group Name: " + group.getString("name"));
                    System.out.println("Location: " + group.getString("location"));
                    System.out.println("");
                }
            }
            
        } catch (URISyntaxException ex) {
            System.out.println(ex.getMessage());
        }
    }
    
}