Using GIT Submodules CRUD

Statement: The purpose of this post is how to use GIT submudule in the existing repository by using CRUD operation for the same. While working on the different git directories, we don’t want to repeat/copy the source code in these repositories. To avoid the same, we just create the parent repository in which we put the common code and make the child repositories as a git submodule to distinguish the code based on the different features.

Prerequisites: Please ensure to have git installation on your working machine.


  • Create a parent repository in your git account (you can clone the existing repository using your username)
  • To make use of other repositories as a child in the above parent repository, make use of git submodule using the below command –
tangupta$ git submodule add
  • Likewise, you can add the different repositories as a child in the parent repository as mentioned above. Now, you can see these changes reflected in the parent directory.
tangupta$ git status
# On branch master
# Changes to be committed:
#   (use "git reset HEAD ..." to unstage)
#   new file:   .gitmodules
#   new file:   doctrine
  • Commit all these changes and push all the child git directories in the parent.
tangupta$ git commit -m 'Added all the submodules' tangupta$ git push
  • Out of the curiosity, you will find the empty folders for all the submodules added in the parent repository.  To sync all the submodules, you need the run the below commands –

tangupta$ git submodule init
tangupta$ git submodul eupdate (You need to do this in case of updation in the child repo.)

  • Finally, if you want to clone the parent repo with all the files of child repo then use the below command to do the same –
tangupta$ git clone --recursive (repository)
  • In case of removing the submodules, you need to remove the entries from the below mentioned files –
  1. .gitmodules file (Remove all the three lines added for the respective submodule).
  2. .git/config file (Remove all the two lines added for the respective submodule).
  3. Remove the path created for the submodule using the below command –

tangupta$ git rm --cached child-dir

  • Finally if you want to pull all the changes which are done in the submodules, use the below command to get the same –
tangupta$ git submodule foreach git pull origin master

Hope, you will get the full understating of how to integrate the parent and child repositories in case cross team working on the same code. GIT rocks !!! Enjoy 🙂



Host your application on the Internet

Statement : The sole purpose of this post is to learn how to host your application to the Internet so that anyone can access it across the world.

Solution :

  • Sign up for the heroku account.
  • Download heroku cli to host you application from your local terminal.
  • Login to your account by using id and password through terminal by using below command –

heroku login

  • Create a new repo on your github account.
  • Now clone your repo on your local machine using the below command –

git clone

  • It’s time to develop your application. Once it is done, push your whole code to your github repo by using below commands –
  1. tangupta-mbp:Cryptocurrency-Concierge tangupta$ git add .
  2. tangupta-mbp:Cryptocurrency-Concierge tangupta$ git commit -m “First commit of cryptocurrency Concierge””
  3. tangupta-mbp:Cryptocurrency-Concierge tangupta$ git push
  • Now you are ready to crate a heroku app. Use the below command for the same –
cd ~/workingDir
$ heroku create
Creating app... done, ⬢ any-random-name |
  • Now commit you application to heroku using the below command –

tangupta-mbp:Cryptocurrency-Concierge tangupta$ git push heroku master

  • It’s time to access your hosted application using the above highlighted url. But most probably you won’t be able to access the same. Make sure one instance of your hosted application is running. Use the below command to do the same –

heroku ps:scale web=1

  • In case, you are getting the below error while running the above command, then you need to make one file name Procfile with no extension and add the same to git repo. Then you need to push the repo to heroku again.

Scaling dynos… !

    Couldn’t find that process type.

  • In my case, to run my spring boot application, I have added the following command in the Procfile to run the application.

          web: java $JAVA_OPTS -Dserver.port=$PORT -jar target/*.war

  • Finally your application should be up and running. In case, you are facing any issues while pushing or running your application, you can check the heroku logs which will help you to troubleshoot the issue by using below commands-

heroku logs –tail

Enjoy coding and Happy Learning 🙂 


Implement secure HTTP server using Grizzly and Jersey

Statement : The purpose of this post is to implement secure HTTP server using Grizzly and Jersey.

Solution :

  • First you just need to create the keystore and truststore files using the below commands and this will ask you certain details about your organization and all –

keytool -genkey -keyalg RSA -keystore ./keystore_client -alias clientKey
keytool -export -alias clientKey -rfc -keystore ./keystore_client > ./client.cert
keytool -import -alias clientCert -file ./client.cert -keystore ./truststore_server

keytool -genkey -keyalg RSA -keystore ./keystore_server -alias serverKey
keytool -export -alias serverKey -rfc -keystore ./keystore_server > ./server.cert
keytool -import -alias serverCert -file ./server.cert -keystore ./truststore_client

  • Add the SSLContextConfiguration Object (containing the details about the keystore and truststore files) in the constructor of GrizzlyHttpServerFactory as per the given below code –

    private static final String KEYSTORE_LOC = “keystore_server”;

    private static final String KEYSTORE_PASS = “123456”;

    private static final String TRUSTSTORE_LOC = “truststore_server”;

    private static final String TRUSTSTORE_PASS = “123456”;

    SSLContextConfigurator sslCon = new SSLContextConfigurator();





URI BASE_URI = URI.create(” + config.getPort());

        String resources = “”;

        BeanConfig beanConfig = new BeanConfig();


        beanConfig.setSchemes(new String[] { “https” });




        final ResourceConfig rc = new ResourceConfig();






        rc.register(new CrossDomainFilter());

    return GrizzlyHttpServerFactory.createHttpServer(BASE_URI, rc, true,

new SSLEngineConfigurator(sslCon).setClientMode(false).setNeedClientAuth(false);

  • Job is done. Now you just need to integrate all the code together. You can refer my github link to get the full code of the implementation. Happy coding 🙂

Generate Swagger UI through Grizzly and Jersey Application.

Statement : Generate Swagger UI for the listing of all the REST APIs through Grizzly and Jersey Application.

  • Add following dependency in pom.xml –






  • Bundle Swagger UI and docs folder through you main application class using the below code –

package com.main;



import org.glassfish.grizzly.http.server.CLStaticHttpHandler;

import org.glassfish.grizzly.http.server.HttpServer;

import org.glassfish.grizzly.http.server.ServerConfiguration;

import org.glassfish.jersey.grizzly2.httpserver.GrizzlyHttpServerFactory;

import org.glassfish.jersey.jackson.JacksonFeature;

import org.glassfish.jersey.server.ResourceConfig;

import com.fasterxml.jackson.jaxrs.json.JacksonJsonProvider;

import io.swagger.jaxrs.config.BeanConfig;

public class MainApp {

// Base URI the Grizzly HTTP server will listen on

public static final URI BASE_URI = URI.create(;);

public static HttpServer getLookupServer() {

String resources = “com.main”;

BeanConfig beanConfig = new BeanConfig();


beanConfig.setSchemes(new String[] { “http” });




final ResourceConfig resourceConfig = new ResourceConfig();






return GrizzlyHttpServerFactory.createHttpServer(BASE_URI, resourceConfig);


public static void main(String[] args) throws IOException {

final HttpServer server = getLookupServer();


ClassLoader loader = MainApp.class.getClassLoader();

CLStaticHttpHandler docsHandler = new CLStaticHttpHandler(loader, “swagger-ui/”);


ServerConfiguration cfg = server.getServerConfiguration();

cfg.addHttpHandler(docsHandler, “/docs/”);



  • Take the latest code of swagger-ui. Copy all the content of the dist folder and create a folder named  swagger-ui inside src/main/resources and paste all the copied contents. Now change the url in index.file which is inside the copied folder like below –


  • Lastly, annotate your controller with @Api and @ApiOperation.

Hope it works. Now to run your Grizzly Jersey Application, go to browser and type localhost:8080/docs/. You will see Swagger UI having all the details of your REST APIs.

Happy coding and sharing as well. 🙂 You can find the git repo for the above implementation.

Git – Permission denied (publickey) Error while cloning the repo on Windows.

The above error comes when either you haven’t made any SSH keys on your local machine or those keys are expired. So to solve this, Please follow the below steps –

  1. Open git bash.
  2. Type cd ~/.ssh. This will take you to the root directory for Git (Likely C:\Users\[YOUR-USER-NAME]\.ssh\ on Windows)
  3. Within the .ssh folder, there should be these two files: id_rsa and
  4. Copy the content of with no extra spaces or lines and paste it into GitHub under the Account Settings > SSH Keys. You can name as per your convenience.
  5. Now git clone or git pull should work.

In case the above files are not created, you can use the below command to do so –

cd ~/.ssh && ssh-keygen

Now follow all the above mentioned steps. Hope it will solve your problem.

Common git commands that you must know

1) Downloads a repo to the local machine:                                git clone

2) Lists all new or modified files to be committed:                   git status

3) Snapshots the file in preparation for versioning:                  git add [file]

4) Records file snapshots permanently in version history:      git commit -m “[descriptive message]”

5) Uploads all local branch commits to Git:                               git push origin master

6) Update local repo with the latest commit:                            git pull

For working knowledge of git, you might want to refer below link:

If you are getting error at the first step, you need to add the key to your account from you git account as mentioned in below link.

Adding new ssh key