Docker Notes

Author: PTHARRISH

Dockers/README.md

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+# 🚀 Docker Quick Start Guide
+
+A simplified reference for getting started with Docker: from installation, pulling images, running containers, and publishing to Docker Hub.
+
+---
+
+## 📥 Installation
+
+Install Docker from the official site:  
+👉 [https://docs.docker.com/get-docker/](https://docs.docker.com/get-docker/)
+
+Verify installation:
+
+```bash
+docker --version
+docker info
+```
+
+---
+
+## 📦 Pulling and Managing Docker Images
+
+```bash
+docker pull <image_name>       # Download image from Docker Hub
+docker images                  # List all downloaded images
+```
+
+Example:
+
+```bash
+docker pull hello-world
+```
+
+---
+
+## 🏃 Running Containers
+
+```bash
+docker run <image_name>        # Runs a new container
+docker run -it <image_name>    # Runs interactively
+```
+
+> Each run creates a new container with a random ID and name.
+
+---
+
+## 📋 Viewing Containers
+
+```bash
+docker ps                      # Show running containers
+docker ps -a                   # Show all containers (running + stopped)
+```
+
+---
+
+## 🧱 Container Management
+
+```bash
+docker start <container_id|name>     # Start a container
+docker stop <container_id|name>      # Stop a container
+docker rename old_name new_name      # Rename a container
+docker rm <container_id|name>        # Remove a stopped container
+docker container prune               # Remove all stopped containers
+```
+
+---
+
+## 🔄 Running Commands in Containers
+
+```bash
+docker exec -it <container_id|name> <command>  # Run command inside container
+docker exec -it my_container node              # Start Node.js shell
+docker exec -it my_container /bin/bash         # Access Linux shell
+```
+
+---
+
+## 📁 Copying Files
+
+### From Host to Container
+
+```bash
+docker cp ./example.txt <container_name>:/example.txt
+```
+
+### From Container to Host
+
+```bash
+docker cp <container_name>:/example.txt ./copied.txt
+```
+
+> Use `cat <filename>` inside the container to view file contents.
+
+---
+
+## 📄 Building Docker Images
+
+### Dockerfile Example:
+
+```Dockerfile
+FROM alpine:latest
+CMD ["echo", "Hello, Docker"]
+```
+
+### Build Image
+
+```bash
+docker build -t my_custom_image .
+```
+
+---
+
+## 🗃️ Docker Volumes (Data Persistence)
+
+```bash
+docker volume create my_volume
+docker run -v my_volume:/data alpine
+docker volume ls
+```
+
+> Volumes allow data to persist even after a container is deleted.
+
+---
+
+## 📦 Docker Compose (Multi-Container Apps)
+
+Create a `docker-compose.yml` file:
+
+```yaml
+version: '3'
+services:
+  web:
+    image: nginx
+    ports:
+      - "80:80"
+```
+
+Start with:
+
+```bash
+docker-compose up
+```
+
+Stop with:
+
+```bash
+docker-compose down
+```
+
+---
+
+## 🚫 Ignoring Files: `.dockerignore`
+
+Create a `.dockerignore` file to exclude files/folders from the image:
+
+```
+node_modules
+*.log
+Dockerfile
+```
+
+---
+
+## 📤 Docker Hub: Push Image
+
+1. Login:
+
+```bash
+docker login
+```
+
+2. Tag the image:
+
+```bash
+docker tag my_image <username>/<repository>:latest
+```
+
+3. Push the image:
+
+```bash
+docker push <username>/<repository>:latest
+```
+
+4. Pull from anywhere:
+
+```bash
+docker pull <username>/<repository>:latest
+```
+
+---
+
+## 🏢 Docker Registry
+
+> A Docker registry is a system for storing and distributing Docker images.
+
+- Docker Hub is the default public registry.
+- Run your own private registry:
+
+```bash
+docker run -d -p 5000:5000 --name registry registry:2
+```
+
+---
+
+## 🛡️ Best Practices
+
+- Use lightweight base images (like `alpine`)
+- Use multi-stage builds for production apps
+- Clean up unused packages in Dockerfile
+- Tag images clearly (e.g., `:v1`, `:latest`, `:prod`)
+- Use `.dockerignore` to reduce image size and build time
+
+---
+
+## ✅ Useful Summary Commands
+
+| Action                 | Command                             |
+|------------------------|-------------------------------------|
+| List Images            | `docker images`                     |
+| Run Container          | `docker run <image>`                |
+| List Containers        | `docker ps -a`                      |
+| Build Image            | `docker build -t name .`            |
+| Exec into Container    | `docker exec -it <id> bash`         |
+| Copy Files             | `docker cp`                         |
+| Push to Docker Hub     | `docker push`                       |
+
+---