SLC-S23W3 - Docker & Devops - Candidate Evaluation Platform

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Welcome to Week 3 of our Tech & Dev Club learning series. After covering project planning, UML diagrams, and methodologies last week, we're now diving into the world of containerization with Docker. This is a crucial DevOps skill that will help you build, deploy, and scale applications more efficiently.

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What you'll Learn.

• What Docker is and why it is useful
• Basic Docker parts like images and containers
• How to make Dockerfiles
• How to use Docker Compose for many containers
• Looking at real Dockerfiles from our project

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What is docker?

Docker is a platform that helps developers put applications in containers. Containers are like small boxes that hold all the app needs. This makes the app work the same on all computers.

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Why docker is good?

1. No more "works on my machine" problems
2. Apps don't mess with each other
3. Containers are small and fast
4. Easy to make more copies when needed
5. Makes testing and deployment simple

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Docker Architecture

_{Docker Architecture created using mermaid}

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Docker has three main parts:

• Docker Client: where you type commands
• Docker Host: the server that runs containers
• Docker Registry: stores Docker images

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Docker components

1. Images

Images are like blueprints for containers. They cannot change.

2. Containers

Containers are running copies of images. They have everything the app needs.

3. Volumes

Volumes save data even when containers stop.

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Understanding Dockerfiles

A Dockerfile is a text file with steps to make a Docker image:

FROM node:16.5.0-alpine      # Base image
WORKDIR /app                 # Sets working directory
COPY package.json ./         # Copies files from host to image
RUN npm install              # Executes commands during build
CMD ["npm", "start"]         # Default command when container starts

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Maindockerfile instructions

• FROM: picks the base image
• WORKDIR: sets the work folder
• COPY/ADD: copies files into the image
• RUN: runs commands when building
• ENV: sets environment variables
• EXPOSE: shows which ports to use
• CMD/ENTRYPOINT: sets the start command

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Docker Compose

Docker Compose helps run many containers together. It uses a YAML file:

version: "3"
services:
  frontend:
    build: ./frontend
    ports:
      - "3000:3000"
    volumes:
      - ./frontend:/app
  backend:
    build: ./backend
    ports:
      - "8080:8080"
    depends_on:
      - database
  database:
    image: postgres:13
    environment:
      - POSTGRES_PASSWORD=password

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Key Docker Compose Ideas

• Services: the containers in your app
• Volumes: storage that stays
• Networks: how containers talk to each other
• Dependencies: which container starts first

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Our Project's Dockerfiles

_{my architectcture application using mermaid}

Let's analyze the Dockerfiles from our project:

Frontend Dockerfile

FROM node:16.5.0-alpine

WORKDIR /app

RUN node -v
RUN apk add libc6-compat
RUN apk add openssh-client
RUN apk add git

COPY package.json ./
COPY package-lock.json ./
RUN npm i

ADD . .
RUN ls -la
RUN chmod +x env.sh
RUN npm run env
RUN cp env-config.js ./public

CMD [ "npm", "run", "start"]

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What this does:

1. Starts with Alpine Linux Node.js
2. Installs needed tools
3. Copies package files first (good for caching)
4. Installs npm packages
5. Copies all project files
6. Sets up environment settings
7. Starts the app

Backend Dockerfile

FROM golang:1.16.5

WORKDIR /go/src/test/

COPY . .
COPY go.mod .
COPY go.sum .
RUN go mod download
RUN go get github.com/pilu/fresh
RUN go get github.com/swaggo/swag/cmd/[email protected]
RUN go get github.com/arsmn/fiber-swagger/v2
RUN go get gorm.io/[email protected]

ENTRYPOINT swag init --parseDependency --parseInternal && fresh

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What this does:

1. Starts with Golang image
2. Sets the work folder
3. Copies all files
4. Downloads Go modules
5. Gets tools for:
   • Hot-reloading
   • API docs
   • Swagger UI
   • Database work
6. Sets up Swagger docs and starts the server

Docker Compose File

version: "3"
services:
  web-dev:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "3000:3000"
    volumes:
      - ./src:/app/src
    environment:
      - CHOKIDAR_USEPOLLING=true
    container_name: front-app

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What this does:

1. Makes a service called "web-dev"
2. Builds it using our Dockerfile
3. Maps port 3000
4. Mounts src folder (for live updates)
5. Sets an environment variable
6. Names the container

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Docker Commands Cheatsheet

Command	Description
docker build -t myapp .	Build an image
docker run -p 3000:3000 myapp	Run a container
docker ps	List running containers
docker images	List images
docker-compose up	Start services defined in docker-compose.yml
docker-compose down	Stop services
docker exec -it container_name bash	Access a running container
docker logs container_name	View container logs

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What's Next?

In Week 4, we'll explore frontend development with React & TypeScript, building on our containerized approach. We'll see how Docker simplifies the development process and helps us create a consistent environment across our tech stack.

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Stay tuned for next week's topic: Frontend Development with React & TypeScript.

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<sub>Authentication interface

Question type selection interface

Interface for adding questions to a test

Interface for adding an MCQ-type question

Interface for inviting a candidate to a test

Candidate welcome interface</sub>

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GitHub Repositories

• Frontend: TalentLens
• Backend: Candidly

Project Resources

• Complete System Overview: Google Drive Link
• Project Presentation Video:

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What can you share in the club?

Our club is all about technology and development including:

• Web & Mobile Development
• AI & Machine Learning
• DevOps & Cloud Technologies
• Blockchain & Decentralized Applications
• Open-source Contributions
• Graphic Design & UI/UX

Any posts related to technology, reviews, information, tips, and practical experience must include original pictures, real-life reviews of the product, the changes it has brought to you, and a demonstration of practical experience

The club is open to everyone. Even if you're not interested in development, you can still share ideas for projects, and maybe someone will take the initiative to work on them and collaborate with you. Don’t worry if you don’t have much IT knowledge , just share your great ideas with us and provide feedback on the development projects. For example, if I create an extension, you can give your feedback as a user, test the specific project, and that will make you an important part of our club. We encourage people to talk and share posts and ideas related to Steemit.

For more information about the #techclub you can go through A New Era of Learning on Steemit: Join the Technology and Development Club. It has all the details about posting in the #techclub and if you have any doubts or needs clarification you can ask.

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Our Club Rules

To ensure a fair and valuable experience, we have a few rules:

1. No AI generated content. We want real human creativity and effort.
2. Respect each other. This is a learning and collaborative space.
3. No simple open source projects. If you submit an open source project, ensure you add significant modifications or improvements and share the source of the open source.
4. Project code must be hosted in a Git repository (GitHub/GitLab preferred). If privacy is a concern, provide limited access to our mentors.
5. Any post in our club that is published with the main tag #techclub please mention the mentors @kafio @mohammadfaisal @alejos7ven
6. Use the tag #techclub, #techclub-s23w3, #country, other specific tags relevant to your post.
7. In this thirdweek's #techclub you can participate from Monday, March 3, 2025, 00:00 UTC to Sunday, March 09, 2025, 23:59 UTC.
8. Post the link to your entry in the comments section of this contest post. (Must)
9. Invite at least 3 friends to participate.
10. Try to leave valuable feedback on other people's entries.
11. Share your post on Twitter and drop the link as a comment on your post.

Each post will be reviewed according to the working schedule as a major review which will have all the information about the post such as AI, Plagiarism, Creativity, Originality and suggestions for the improvements.

Other team members will also try to provide their suggestions just like a simple user but the major review will be one which will have all the details.

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Rewards System

Sc01 and Sc02 will be visiting the posts of the users and participating teaching teams and learning clubs and upvoting outstanding content. Upvote is not guaranteed for all articles. Kindly take note.

Each week we will select Top 4 posts which has outperformed from others while maintaining the quality of their entry, interaction with other users, unique ideas, and creativity. These top 4 posts will receive additional winning rewards from SC01/SC02.

Note: If we find any valuable and outstanding comment than the post then we can select that comment as well instead of the post.

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Best Regards
Technology and Development Club Team