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Docker Topics Overview
https://github.com/guptaroshan/docker-topics

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Docker Topics Overview

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# Docker Learning Topics Overview



Docker Concepts



## 1. Introduction to Docker



### What is Docker?



Docker is a platform for developing, shipping, and running applications in containers. Containers allow developers to package an application with all its dependencies and ship it as a single unit.



### Benefits of using Docker:



- Consistent environment across different stages of development.

- Isolation of applications.

- Efficient resource utilization.



### Key concepts:



- **Images:** Immutable, lightweight, and standalone packages that contain everything needed to run a piece of software, including the code, runtime, libraries, and configuration.

- **Containers:** Running instances of Docker images.

- **Dockerfile:** A text file with instructions to build a Docker image.

- **Docker Hub:** A public registry to find and share container images.



## 2. Installing Docker



### Installing Docker on Windows:



1. Download Docker Desktop from the [Docker website](https://www.docker.com/products/docker-desktop).

2. Follow the installation instructions.

3. Verify the installation:

   ```bash

   docker --version

   ```



### Installing Docker on macOS:



1. Download Docker Desktop for Mac.

2. Follow the installation instructions.

3. Verify the installation:

   ```bash

   docker --version

   ```



### Installing Docker on Linux:



1. Update your existing list of packages:

   ```bash

   sudo apt-get update

   ```

2. Install a few prerequisite packages:

   ```bash

   sudo apt-get install apt-transport-https ca-certificates curl software-properties-common

   ```

3. Add the GPG key for the official Docker repository:

   ```bash

   curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

   ```

4. Add the Docker repository to APT sources:

   ```bash

   sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

   ```

5. Update your package database with the Docker packages from the newly added repo:

   ```bash

   sudo apt-get update

   ```

6. Install Docker:

   ```bash

   sudo apt-get install docker-ce

   ```

7. Verify the installation:

   ```bash

   docker --version

   ```



## 3. Docker Architecture



### Docker Engine



The core component of Docker that creates and manages containers.



### Docker Daemon



Runs on the host machine and listens for Docker API requests to manage Docker objects such as images, containers, networks, and volumes.



### Docker Client



CLI tool that allows users to interact with the Docker daemon.



### Docker Registries



Stores Docker images. Docker Hub is a public registry, but you can also set up private registries.



## 4. Working with Docker Images



### Understanding Docker images



Images are the building blocks of containers. They are created from a set of read-only layers.



### Pulling images from Docker Hub



```bash

    docker pull nginx

```



### Listing images



```bash

    docker images

```



### Removing images



```bash

    docker rmi 

```



## 5. Creating Docker Images



### Writing a Dockerfile



A Dockerfile is a script containing a series of instructions on how to build a Docker image.



**Example Dockerfile:**



```Dockerfile

    # Use an official Python runtime as a parent image

    FROM python:3.8-slim



    # Set the working directory

    WORKDIR /app



    # Copy the current directory contents into the container at /app

    COPY . /app



    # Install any needed packages specified in requirements.txt

    RUN pip install --no-cache-dir -r requirements.txt



    # Make port 80 available to the world outside this container

    EXPOSE 80



    # Define environment variable

    ENV NAME World



    # Run app.py when the container launches

    CMD ["python", "app.py"]

```



### Building images from a Dockerfile



```bash

    docker build -t my-python-app .

```



### Best practices for writing Dockerfiles



- Keep Dockerfiles small and simple.

- Use .dockerignore to exclude files and directories from the build context.

- Leverage caching by ordering Dockerfile instructions from least to most frequently changed.



### Tagging images



```bash

    docker tag my-python-app myrepo/my-python-app:v1.0

```



## 6. Docker Containers



### Understanding containers



Containers are lightweight, portable, and self-sufficient units that can run any application.



### Running containers



```bash

    docker run -d -p 80:80 --name mynginx nginx

```



### Managing containers (start, stop, restart, remove)



```bash

    docker start mynginx

    docker stop mynginx

    docker restart mynginx

    docker rm mynginx

```



### Inspecting containers



```bash

    docker inspect mynginx

```



### Attaching to and interacting with containers



```bash

    docker exec -it mynginx /bin/bash

```



## 7. Docker Networking



### Overview of Docker networking



Docker networking allows containers to communicate with each other and with the host system.



### Types of Docker networks (bridge, host, overlay, etc.)



- **Bridge:** Default network driver. Containers on the same bridge network can communicate.

- **Host:** Removes network isolation between the container and the Docker host.

- **Overlay:** Enables Swarm services to communicate with each other.



### Creating and managing networks



```bash

    docker network create mynetwork

    docker network ls

    docker network rm mynetwork

```



### Connecting containers to networks



```bash

    docker network connect mynetwork mynginx

```



## 8. Docker Volumes and Storage



### Understanding Docker volumes



Volumes are the preferred mechanism for persisting data generated by and used by Docker containers.



### Creating and managing volumes



```bash

    docker volume create myvolume

    docker volume ls

    docker volume rm myvolume

```



### Mounting volumes in containers



```bash

    docker run -d -p 80:80 --name mynginx -v myvolume:/data nginx

```



### Persistent storage in Docker



Volumes provide persistent storage that is independent of the container lifecycle.



## 9. Docker Compose



### Introduction to Docker Compose



Docker Compose is a tool for defining and running multi-container Docker applications.



### Writing `docker-compose.yml` files



```yaml

    version: '3'

    services:

      web:

        image: nginx

        ports:

          - "80:80"

      db:

        image: postgres

        environment:

          POSTGRES_PASSWORD: example

```



### Building and running multi-container applications with Docker Compose



```bash

    docker-compose up

    docker-compose down

```



### Docker Compose commands



```bash

    docker-compose build

    docker-compose start

    docker-compose stop

```



## 10. Docker Registry



### Understanding Docker Registry



A storage and distribution system for named Docker images.



### Using Docker Hub



Docker Hub is a cloud-based registry service for sharing Docker images.



### Setting up a private Docker Registry



```bash

    docker run -d -p 5000:5000 --name registry registry:2

```



### Pushing and pulling images from a private registry



```bash

    docker tag my-python-app localhost:5000/my-python-app

    docker push localhost:5000/my-python-app

    docker pull localhost:5000/my-python-app

```



## 11. Dockerizing Applications



### Containerizing a simple web application (e.g., Node.js, Python Flask)



**Example Dockerfile for a Node.js app:**



```Dockerfile

    FROM node:14



    WORKDIR /app



    COPY package*.json ./



    RUN npm install



    COPY . .



    EXPOSE 3000



    CMD ["node", "app.js"]

```



### Best practices for containerizing applications



- Use official base images.

- Minimize the number of layers.

- Use multi-stage builds for smaller images.



## 12. Managing Docker Containers



### Using Docker commands for container management



```bash

    docker ps

    docker inspect

    docker logs

    docker stats

```



### Monitoring and logging containers



```bash

    docker logs mynginx

    docker stats mynginx

```



### Using tools like `docker stats` and `docker logs`



```bash

    docker stats

    docker logs

```



## 13. Docker Security



### Security best practices



- Run containers as a non-root user.

- Keep Docker and Docker images up to date.

- Use trusted images.



### Running containers as non-root users



```Dockerfile

    FROM node:14

    USER node

```



### Securing Docker daemon and network



- Use TLS to secure Docker daemon.

- Limit container privileges.

- Use network policies to restrict container communication.



### Scanning images for vulnerabilities



Use tools like Trivy, Clair, and Docker's built-in scanning.



## 14. Advanced Docker Topics



### Docker Swarm and orchestration



Docker Swarm is a container orchestration tool native to Docker.



### Using Docker in CI/CD pipelines



Integrate Docker with CI/CD tools like Jenkins, GitLab CI, and CircleCI.



### Integrating Docker with Kubernetes



Kubernetes is a container orchestration system that extends Docker's capabilities.



### Docker on cloud platforms (AWS, GCP, Azure)



Use Docker with cloud services like AWS ECS, Google Kubernetes Engine, and Azure Container Instances.