refactor: change folder structure

2025-07-18 13:02:13 +03:30
parent 835f833927
commit 3c05411a29
1329 changed files with 116 additions and 38 deletions
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+
+## What is Docker?
+
+Docker is a platform that allows you to package applications with all their dependencies into a standardized unit called a **container**. These containers are portable, isolated, and consistent across environments.
+
+---
+
+## What is a Container?
+
+A container is a lightweight, standalone executable package that includes everything needed to run an application: code, runtime, libraries, and configurations.
+
+Containers are stored in **container repositories**:
+- Public repositories: [Docker Hub](https://hub.docker.com)
+- Private repositories: Used by organizations for internal deployments
+
+---
+
+## Why Containers?
+
+### Before Containers:
+- Developers shared artifacts (e.g., `.jar` files) with setup instructions.
+- Operators had to install dependencies manually.
+- Setup was error-prone and inconsistent across OS environments.
+
+### With Containers:
+- Everything is bundled together and works the same everywhere.
+- No need to install dependencies manually.
+- Runs in its own isolated environment.
+- Easy to version, share, and deploy (just one command).
+- Multiple versions of the same app can run simultaneously.
+
+---
+
+## Image vs. Container
+
+|Term|Description|
+|---|---|
+|**Image**|A snapshot or package (the blueprint). Immutable.|
+|**Container**|A running instance of an image. Has its own file system, environment, and process.|
+Running an image creates a container.
+
+---
+
+## Docker vs Virtual Machine
+
+| Feature         | Docker             | Virtual Machine    |
+| --------------- | ------------------ | ------------------ |
+| Virtualizes     | Application layer  | Full OS kernel     |
+| Startup time    | Seconds            | Minutes            |
+| Size            | MBs                | GBs                |
+| Isolation       | OS-level           | Hardware-level     |
+| Performance     | Near-native        | Heavier overhead   |
+| Host dependency | Shares host kernel | Has its own kernel |
+
+Docker runs natively on Linux; on Windows/macOS it uses **Docker Desktop**, which runs Linux under WSL2 or HyperKit.
+
+---
+
+## Docker Architecture
+
+### Layers of a Docker Image:
+
+- Base Layer: Usually a minimal Linux distribution (e.g., `alpine`)
+- Application Layer: Your app and its dependencies
+
+Each image is made of **layers** stacked on top of each other.
+
+---
+
+## Docker Installation
+
+To use Docker on:
+
+- **Linux**: Install Docker engine directly.
+- **Windows/macOS**: Use Docker Desktop, which includes WSL2 integration or virtualization backend.
+
+---
+
+## Docker Commands: Basics
+
+```bash
+# Run a container from an image
+docker run image-name
+
+# List running containers
+docker ps
+
+# List all containers (running and stopped)
+docker ps -a
+
+# Stop a running container
+docker stop CONTAINER_ID
+
+# Start a stopped container
+docker start CONTAINER_ID
+```
+
+### Port Binding
+
+```bash
+docker run -p HOST_PORT:CONTAINER_PORT image-name
+```
+
+This binds a container’s port to a specific port on your machine.
+
+---
+
+## Debugging Containers
+
+```bash
+# View logs
+docker logs CONTAINER_ID
+
+# Start a container with detached mode and port
+docker run -d -p 3000:3000 image-name
+
+# Open an interactive shell inside a running container
+docker exec -it CONTAINER_ID /bin/bash
+```
+
+You can assign names to containers using `--name`.
+
+---
+
+## Docker Networking
+
+### Concept:
+
+Containers can communicate with each other over a virtual network.
+
+```bash
+# List networks
+docker network ls
+
+# Create a new network
+docker network create my-network
+
+# Run container in a network
+docker run --net my-network ...
+```
+
+Example: MongoDB + Mongo Express on same network can communicate via service name.
+
+---
+
+## Docker WSL2 Error (Windows)
+
+### Issue:
+
+```
+Failed to configure network (networkingMode Nat)...
+```
+
+### Fix:
+
+Create or edit the file at:
+
+```
+C:\Users\LENOVO\.wslconfig
+```
+
+Add:
+
+```
+[wsl2]
+networkingMode=None
+```
+
+Then restart Docker Desktop.
+
+---
+
+## Docker Compose
+
+Docker Compose lets you define and run multi-container apps using YAML.
+
+### Example:
+
+```yaml
+version: '3'
+services:
+  app:
+    image: my-app
+    ports:
+      - "3000:3000"
+    environment:
+      - NODE_ENV=production
+
+  mongodb:
+    image: mongo
+    ports:
+      - "27017:27017"
+    environment:
+      - MONGO_INITDB_ROOT_USERNAME=admin
+      - MONGO_INITDB_ROOT_PASSWORD=secret
+```
+
+### Commands:
+
+```bash
+docker-compose -f docker-compose.yml up
+docker-compose down
+```
+
+- All services run in the same default Docker network.
+- Indentation in YAML is **critical**.
+
+---
+
+## `Dockerfile`
+
+A `Dockerfile` is a script used to build Docker images.
+
+### Example:
+
+```Dockerfile
+FROM node:18
+
+ENV NODE_ENV=production
+
+# Inside container
+RUN mkdir -p /home/app
+
+# Copy from host into container
+COPY ./home/app /home/app
+
+WORKDIR /home/app
+
+CMD ["node", "server.js"]
+```
+
+Build with:
+
+```bash
+docker build -t my-node-app .
+```
+
+Then run it with:
+
+```bash
+docker run -p 3000:3000 my-node-app
+```
+