Wednesday, 22 January 2025
Tuesday, 21 January 2025
Docker: Accelerated Container Application Development
1. Developers can deploy, run, and manage applications.
2. Deploy applications quickly.
3. Docker is a containerization platform that simplifies the process of deploying and managing applications. Applications run along with their dependencies.
Docker Images :
1. A copy of our project.
2. Images are made from source code, libraries, and external dependencies.
3. Images are created from source code.
4. Example: Node setup, application code, installed libraries, Docker files.
5. Once an image is created, it cannot be updated; we can create a new image instead.
Docker Container :
1. A container runs applications using images.
2. Containers run independently.
3. Example: If 3 images are available, all these images can run independently.
Docker Commands :
1. docker build -t folder/dockername . // Creates a project image.
2. docker run -p 5000:5000 -d dockerImageName // Runs a container.
3. docker ps // Shows all running containers.
4. docker logs container_id // Displays project logs.
5. docker image prune // Removes unused images.
6. docker service scale web-app=2 // Scales the web-app service to two replicas.
7. docker service update --image <new-image> service_name // Updates a Docker container's image without causing downtime.
Docker File Example :
1. Create a file named Dockerfile in the root directory of your backend project.
2. In this Dockerfile, write the following code:
# Use Node.js version 20 as the base image
FROM node:20
# Set the working directory inside the container
WORKDIR /node-practical
# Copy package.json and package-lock.json to the working directory
COPY package*.json ./
# Install dependencies
RUN npm install
# Copy the entire project to the container
COPY . .
# Specify the command to run the application
CMD ["node", "index.js"]
3. Here’s an example of a docker-compose.yml file for a microservices architecture:
docker-compose.yml Example :
version: '3.9'
services:
db:
image: postgres:14-alpine
restart: always
environment:
POSTGRES_USER: postgres
POSTGRES_PASSWORD: DBPass@123
POSTGRES_DB: DBNAME
POSTGRES_HOST_AUTH_METHOD: trust
gateway:
build:
dockerfile: Dockerfile
context: ./gateway
command: npm run start:prod
restart: always
ports:
- "5000:5000"
depends_on:
- db
environment:
JWT_SECRET: secret@123
JWT_EXPIRESIN: 2d
REDIS_HOST: localhost
REDIS_PORT: 6379
REDIS_DB: TestFinAssetMgmt //if use redis
volumes:
- /gateway/src/app/node_modules
auth:
build:
dockerfile: Dockerfile
context: ./auth
command: npm run start:prod
restart: always
ports:
- "5100:5100"
depends_on:
- db
environment:
DB_TYPE : postgres
DB_HOST : HOST_name
DB_PORT : 5432
DB_USERNAME : DBUSERNAME
DB_PASSWORD : DB PASS
DB_DATABASE : DBDATABASENAME
DB_SYNC : true
JWT_SECRET : secret@123
JWT_EXPIRESIN : 2d
RESET_PASSWORD_URL : http://3.15.153.226:3000
volumes:
- /auth/src/app/node_modules
mail:
build:
context: ./mail
command: npm run start:prod
restart: always
ports:
- "5200:5200"
depends_on:
- db
- auth
- gateway
environment:
EMAIL_HOST : smtp.gmail.com
EMAIL_USER : SMTP-email-pass
EMAIL_PASSWORD : smtp-password
volumes:
- /mail/src/app/node_modules
Gmail : SMTP : Simple Mail Transfer Protocol
1. Go to google Gmail account setting
→ Go to Forwarding and POP/IMAP
→ Enabled IMAP access.
2. After go to : manage your google account
→ Go to security page
→ Less secure option is enable
3. Email smtp setting :
→ Server name : smtp.gmail.com ,
→ Port : 587 for Gmail account,
→ Username and password google account
→ Sender name enter
→ Save
AWS SES : Simple Email Service
1. Download access key and secret key excel file.
2. Go to verified identity -> Create Identity -> Verify email received in email account and verified.
3. npm install aws-sdk
const AWS = require("aws-sdk");
const awsConfig = {
accessKeyId: AWS_ACCESS_KEY_ID,
secretAccessKey: AWS_SECRET_ACCESS_KEY,
region: process. AWS_REGION,
};
const SES = new AWS.SES(awsConfig);
const sendEmail = async () => {
try {
//prepare email to send
const params = {
Source: "verifiedemailaddress@gmail.com" //verified email address
Destination: {
ToAddresses: "to@gmail.com",
},
Message: {
Subject: {
Charset: "UTF-8",
Data: "OTP Verification",
},
Body: {
Html: {
Charset: "UTF-8",
Data: `<h1>Your verification code is 12345</h1>`,
},
},
},
};
const emailSent = SES.sendEmail(params).promise();
emailSent
.then((data) => {
console.log(data);
})
.catch((err) => {
console.log(err);
});
} catch (error) {
console.log(error);
}
};
module.exports = sendEmail;
Difference between MySQL and PostgreSQL.
1. MySQL:
Relational database.
Case-insensitive.
Limited basic data type support.
Uses indexes: R, B, Hash.
Concurrency control.
2. PostgreSQL:
Object-relational database (DB).
Case-sensitive.
Advanced data type support.
Multiple types of indexes.
Multiversion concurrency control (MVCC).
JavaScript Hoisting :
1. Functions, variables, and class definitions are hoisted to the top.
2. let and const are initialized only after they are used.
3. The most important concepts in JavaScript.
4. To avoid bugs, always declare all variables at the beginning of every scope.
Monday, 20 January 2025
JavaScript Pure and Impure Functions.
1. JavaScript Pure Functions.
JavaScript Pure Function Without modifying value return. like predictable out value.
function add(x) {
return x + 1;
}
console.log(add(10)); // output : 11
console.log(add(11)); // output : 12
console.log(add(12)); // output : 13
2. JavaScript Impure Functions.
JavaScript Impure Function value is change every time.
let x = 10;
function add() {
return x++;
}
console.log(add()); // output : 10
console.log(add()); // output : 11
console.log(add()); // output : 12
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