DEV Community: Arpan Adhikari

Serverless Node-Mongo API with DigitalOcean Functions

Arpan Adhikari — Mon, 29 Aug 2022 19:20:18 +0000

Hello Folks,

We will discuss the newly launched DigitalOcean Functions - A way to go Serverless and will create a node.js application that can connect and store data to MongoDB. It's so simple to create a Serverless function with DigitalOcean.

Functions are blocks of code that run on demand without the need to manage any infrastructure. Develop on your local machine, test your code from the command line (using doctl), then deploy to App Platform — no servers required.

Prerequisites:

DigitalOcean Account-$100 Free on signup
Install doctl cli
MongoDB Credentials(URI)

Step 1: Init

Once you have setup and install doctl in your system. Check if everything is working by running the following command:

doctl serverless status

The above command should return something like this:

Connected to function namespace 'fn-feb132ee-706a-4f13-9c81-f24a3330260a' on API host 'https://faas-nyc1-78edc.doserverless.co'

Now initialise the project by running (node-mongo-serverless is our project name here, you can choose any preferable name):

doctl serverless init --language js node-mongo-serverless

The Project folder will be created with the following directory structure:

node-mongo-serverless/
├── packages
│   └── sample
│       └── hello
│           └── hello.js
└── project.yml

Now we will rename the files and create a .env file in the root directory such that the new structure will look like the following:

node-mongo-serverless/
├── packages
│   └── mongodb
│       └── postData
│           └── index.js
└── project.yml
└── .env

Step 2: Configure

Now we need to modify the project.yml file accordingly. It will be like the following. We need to modify package name and actions name.

targetNamespace: ''
parameters: {}
packages:
  - name: mongodb
    parameters: {}
    annotations: {}
    actions:
      - name: postData
        binary: false
        main: ''
        runtime: 'nodejs:default'
        web: true
        parameters: {}
        environment: {}
        annotations: {}
        limits: {}
environment:
  DATABASE_URL: ${MONGO_URI}

Now we will open and modify the .env file in the root folder with the MongoDB URI.

.env file will look something like the following. (Replace the value with your own MongoDB URI.)

MONGO_URI='mongodb://myDBReader:D1fficultP%40ssw0rd@mongodb0.example.com:27017/?authSource=admin'

Now we will run the following commands one by one:

cd node-mongo-serverless/packages/mongodb/postData
npm init -y
npm install --package-lock-only mongodb

The above commands will create packages.json file in the node-mongo-serverless/packages/mongodb/postData directory and add the mongodb package.

Step 3: Add code to function

We can now create our main function in the index.js file we already have.
First remove all the content of the index.js file and replace with the following code.

const MongoClient = require('mongodb').MongoClient;

async function main() {
    const uri = process.env['DATABASE_URL'];
    let client = new MongoClient(uri);

    let data = { "name":"Arpan" };
    try {
        await client.connect();
        await client.db("namedb").collection("names").insertOne(data);
        console.log(`added ${data} to database.`);
        return { ok: true };
    } catch (e) {
        console.error(e);
        return {
            "body": { "error": "There was a problem adding the data to the database." },
            "statusCode": 400
        };
    } finally {
        await client.close();
    }
}

module.exports.main = main;

The function will add data to the MongoDB database.
That's it. We are all done now. We can proceed to deploy our function now.

Step 4: Deploy and Test the Function

We navigate to the root directory of the project where the project.yml is and run the following command to connect to the Serverless namespace.

doctl serverless connect

Once you get a positive response like "Connected to function namespace" you can run the following command to deploy the function.

doctl serverless deploy .

For the above command, you must be in the root directory of the project. You should see a success message about the deployment.

Run the following command to get the URL of the function API, where you can hit to store the data.

doctl serverless functions get mongodb/postData --url

You can copy and paste the returned URL into your local browser or postman or any other tool/package. you will receive the response from the index.js file if the data is inserted properly into MongoDB.

Hope you enjoyed the article. For any queries feel free to ask in the comments.

Leetcode Two Sum Problem | DSA | Python

Arpan Adhikari — Sat, 02 Apr 2022 18:15:33 +0000

Leetcode Two Sum Problem link: https://leetcode.com/problems/two-sum/

I have tried to explain both the bruteforce approach as well as the optimal approach. Easy two sum problem solution. If you are preparing for DSA rounds or for SDE interview then this is for you.If you have any queries feel free to leave a comment.

Problem

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

You can return the answer in any order.

Example 1:
Input: nums = [2,7,11,15], target = 9
Output: [0,1]
Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].


Example 2:
Input: nums = [3,2,4], target = 6
Output: [1,2]

Example 3:
Input: nums = [3,3], target = 6
Output: [0,1]

Solution 1 : [Bruteforce Method]

from typing import List
   def twoSum(self, nums: List[int], target: int) -> List[int]:
        for i in range(len(nums)):
            for j in range(i, len(nums)):
                if i!=j:
                    if nums[i] + nums[j] == target:
                        return [i, j]

Solution 2 : [Optimal Solution]

from typing import List
 def twoSum(list: List[int], target: int) -> List[int]:
    if len(list) <= 1:
        return 'Please pass an array with atleast two elements'
    hashTable = {}
    for i in range(len(list)):
        complement =  target  - list[i]
        if complement in hashTable:
            return [list.index(complement), i]
        hashTable[list[i]] = list[i]

I have created a video explaining the solution.

.

Install Jitsi Meet Video Conferencing tool on Ubuntu

Arpan Adhikari — Thu, 21 Jan 2021 20:27:16 +0000

In this article I will share how to install and setup jitsi meet on a Ubuntu / Debian server. It will take few minutes to install and setup your own video conferencing server.

Jitsi meet is a free open source tool by which you can host your own video conferencing server.

Prerequisites

A fresh ubuntu server instance with an IPv4 address xx.xx.xx.xx (eg. 192.16.0.1 )

A root user with password or ssh keys

A domain meet.yoursite.com being pointed to the server instance mentioned above.

Pointing Domain To Your Server

Go to your registrar (eg. Godaddy, Namecheap, etc)
Find Manage Your DNS records
Complete the required fields:
- Host: The host name, or prefix, for the subdomain. For example, enter meet to create a subdomain for meet.yoursite.com.
- Points to: The IP address you are setting as the destination for the host. This is usually the IP address of a hosting account where the site for your subdomain lives.
- TTL: How long the server should cache information. The TTL is set to 1 hour by default.
Save it

Connecting to your server Via SSH:

IF YOU HAVE .pem or .ppk files ( SSH keys ) for logging in to ssh Follow the below Steps Else Skip this

Open Terminal ( In Apple Machines ) / Open Putty ( Installation Link : https://the.earth.li/~sgtatham/putty/latest/w64/putty.exe ) 
For Mac :
Type: ssh -i key.pem root@yourserversip
For Windows Fill The putty Fields
- At Host put your servers IP
- Select SFTP from the dropdown
- Then choose keyfile option and select the key.ppk file
- Then Connect Now you will be able to access your server via your machine

If you have the password for ssh login Follow the Below Steps

For MacOS
- Enter in terminal – ssh root@yourserverip
- Then Enter the password
For windows
- At Host put your servers IP
- Select SFTP from the dropdown
- Then choose username/password option
- Enter your Username and Password
- Connect ### If you are loggin with user other than root Then after login enter - sudo su –

Make sure the Following Ports are open For your server if not Add it

Add HTTP and HTTPS rules from source Anywhere.

Add custom TCP port 4443 rule from source Anywhere .

Add custom UDP port 10000 rule from source Anywhere .

Now we are ready to install JITSI MEET

Enter the following in the terminal one by one:
Make sure to replace meet.yoursite.com with yours

sudo hostnamectl set-hostname jitsimeet

sudo sed -i 's/^127.0.1.1.*$/127.0.1.1 meet.yoursite.com jitsimeet/g' /etc/hosts

sudo apt update

sudo apt install -y openjdk-8-jre-headless

echo "JAVA_HOME=$(readlink -f /usr/bin/java | sed "s:bin/java::")" | sudo tee -a /etc/profile source /etc/profile

sudo apt install -y nginx

sudo systemctl start nginx.service

sudo systemctl enable nginx.service

cd

wget -qO - https://download.jitsi.org/jitsi-key.gpg.key | sudo apt-key add –

sudo sh -c "echo 'deb https://download.jitsi.org stable/' > /etc/apt/sources.list.d/jitsi-stable.list"

sudo apt update -y

sudo apt install -y jitsi-meet

During the installation, when you are asked to provide the hostname of the current installation, type in the meet.yoursite.com you setup earlier and then press ENTER.

When you are asked about the SSL certificate, highlight the Generate a new self-signed certificate (You will later get a chance to obtain a Let's Encrypt certificate) option and then press ENTER.

Once Jitsi Meet successfully installed, use the following script to apply for a Let's Encrypt SSL certificate:
Enter the Following in Terminal
sudo /usr/share/jitsi-meet/scripts/install-letsencrypt-cert.sh

Tada !!! You have successfully installed jitsi meet on your ubuntu server.

Now open your browser with http://meet.yoursite.com

Bonus:

You can change the Logo in /usr/share/jitsi-meet/images/watermark.png
Replace watermark.png with yours
Change Jitsi name and other settings easily at:
/usr/share/jitsi-meet/interface_config
Change Background Color and Front Page Texts at:
/usr/share/jitsi-meet/libs/app.bundle.min.js
Change Site title and other meta data at:
/usr/share/jitsi-meet/title.html

Check out this free $100 credit for DigitalOcean Servers - https://m.do.co/c/0eeab663047a

Hope you enjoyed the article. For any queries feel free to leave a comment below.

Thank you.

Host your Vue.js Application for #FREE

Arpan Adhikari — Wed, 20 Jan 2021 18:23:39 +0000

Hello everyone,
I have created a guide on creating and hosting a Vuejs Application for free with DigitalOcean App Platform.

Check out my video guide here:

How to host your static site for free with DigitalOcean App Platform

Arpan Adhikari — Thu, 07 Jan 2021 19:21:24 +0000

Hi everyone,
In this guide I will show you how you can host your static site for free with DigitalOcean App Platform and integrate git repo with DigitalOcean. Hope you like it.

Check out my video guide here:

Simple Quiz Application With Timer - Vue

Arpan Adhikari — Sat, 12 Dec 2020 16:50:00 +0000

What I built

A simple One Page Quiz Application Written in Vue 2. Which Can be used in any Quiz or Other Applications.

Category Submission:

Random Roulette

App Link

https://simple-quiz-vue-56qwg.ondigitalocean.app

Screenshots

Description

This is an simple OnePage Application Written in Vue2. You can integrate it anywhere in your vueJS application. It has a simple timer with loading animations. Bootstrap-vue is used for the ui component. Since it is open source feel free to contribute to this simple quiz Application here: https://github.com/arpan45/simple-quiz-vue .

Link to Source Code

https://github.com/arpan45/simple-quiz-vue

Permissive License

MIT License

Background

A simple Quiz App Can be integrated anywhere. Most of the Applications which are mainly focused on education purpose can use it for simple challenging Quiz.

How I built it

First time used the DigitalOcean App Platform for deploying my App. It auto detects everything from the repo.CI/CD is just buttery smooth with digital ocean app platform. I just put my code to GitHub . Building and Serving App was so easy with a clean interface. I just selected the repository and set the dist directory for deploying. That is it. You can deploy the Application in just a click.

Additional Resources/Info

I have used Unsplash for the landing page image.
Bootstrap-Vue as UI components Library.

Any Component Library Like Vuetify or Vusax for Vue 3 ?

Arpan Adhikari — Sat, 07 Nov 2020 18:22:32 +0000

Any Component Library Like Vuetify or Vusax for Vue 3 ? Any suggestions for vue 3 component library ?

How many sites can be hosted in 1 Hobby dyno?

Arpan Adhikari — Mon, 17 Feb 2020 05:34:52 +0000

How many static or dynamic websites can be hosted with one hobby dyno?

How to find the address of a Variable in PHP?

Arpan Adhikari — Tue, 11 Feb 2020 11:21:46 +0000

How to print the address of a Variable in PHP?

Best option for backend

Arpan Adhikari — Sun, 12 Jan 2020 18:51:43 +0000

Hi, I want to develop an educational web application with apis that can be integrated with android application.
What is the best option for this kind of applications. Nodejs + MongoDB or PHP + MySQL