Code-Memo

Docker

Docker is an open-source platform that automates the deployment, scaling, and management of applications in lightweight, portable containers. Containers package an application and its dependencies together, ensuring consistency across different environments.

Docker simplifies the process of creating, deploying, and running applications by using containers, which allow developers to package up an application with all the parts it needs, such as libraries and other dependencies, and ship it all out as one package.

Containerization is a lightweight form of virtualization that involves encapsulating an application and its dependencies into a container. Unlike traditional virtual machines, containers share the host system’s kernel but run in isolated user spaces. This approach provides several advantages:

Isolation: Each container runs in its own isolated environment, preventing conflicts between applications.
Lightweight: Containers share the host OS kernel, making them more resource-efficient compared to virtual machines.
Portability: Containers can run consistently across different environments, from a developer’s laptop to a production server.
Fast Startup: Containers can start and stop quickly, which enhances development and deployment processes.

Docker Architecture

Docker’s architecture is based on a client-server model, which includes several key components: Docker Engine, Docker Daemon, Docker Client, Docker Images, and Docker Containers.

Docker Engine
- The core component of Docker, responsible for building, running, and managing Docker containers.
- Composed of several smaller components, including the Docker Daemon, Docker API, and Docker CLI.
Docker Daemon (dockerd)
- A background service running on the host machine.
- Manages Docker containers, images, networks, and storage volumes.
- Listens for Docker API requests and manages Docker objects.
Docker Client (docker)
- A command-line tool used by users to interact with the Docker Daemon.
- Sends commands to the Docker Daemon using the Docker API.
- Commands can be used to build, run, and manage Docker containers and images.
Docker Images
- Read-only templates used to create Docker containers.
- Define the contents and startup behavior of a container, including the operating system, application code, libraries, and dependencies.
- Built using a Dockerfile, which contains a series of instructions to assemble an image.
- Stored in Docker registries like Docker Hub or private registries.
Docker Containers
- Lightweight, standalone, and executable packages of software that include everything needed to run an application: code, runtime, libraries, and environment variables.
- Created from Docker images and run in isolated environments on the host machine.
- Containers can be started, stopped, moved, and deleted, making them highly portable and flexible.

Docker Engine

Docker Engine is the core component of Docker, providing the runtime environment for containers. It consists of several smaller components:

Docker Daemon: Handles container operations.
Docker API: An interface that allows Docker to be integrated with other tools and services.
Docker CLI: The command-line interface for interacting with Docker.

Docker Daemon (`dockerd`)

The Docker Daemon runs on the host machine and is responsible for:

Managing Docker Objects: Containers, images, networks, and storage volumes.
Listening to API Requests: Processes API requests sent by the Docker Client.
Executing Container Operations: Such as starting, stopping, and deleting containers.

Docker Client (`docker`)

The Docker Client is the primary way users interact with Docker. Key commands include:

docker build: Builds an image from a Dockerfile.
docker pull: Downloads an image from a registry.
docker run: Creates and starts a container from an image.
docker ps: Lists running containers.
docker stop: Stops a running container.

Docker Images

Docker Images are templates used to create containers. Key concepts include:

Layers: Images are built in layers, each representing a step in the build process. Layers are cached, which makes building images more efficient.
Dockerfile: A text file that contains a series of instructions for building an image. Example instructions include FROM (base image), RUN (execute a command), and COPY (copy files into the image).

Docker Containers

Docker Containers are instances of Docker Images. Key concepts include:

Isolation: Each container runs in its own isolated environment, ensuring that applications do not interfere with each other.
Portability: Containers can run consistently across different environments.
Lifecycle: Containers can be created, started, stopped, paused, and deleted. They can also be committed to create new images.

Example Workflow

Create a Dockerfile: Write a Dockerfile with the necessary instructions to build your application image.
Build an Image: Use docker build to create an image from the Dockerfile.
Run a Container: Use docker run to start a container from the image.
Manage Containers: Use commands like docker ps, docker stop, and docker rm to manage the container’s lifecycle.

Docker Images

Creating Images

Docker images are created from a series of instructions written in a Dockerfile. These instructions define what goes into the image, including the operating system, application code, dependencies, and any other necessary files.

Using docker build:
- The docker build command is used to create an image from a Dockerfile.
- Basic syntax: docker build -t <image_name>:<tag> <path_to_dockerfile>.
- Example: docker build -t myapp:latest .
Tagging Images:
- Tags are used to version control your images.
- When building an image, you can specify a tag using the -t option.
- Example: docker build -t myapp:v1.0 .

Using Dockerfile

A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image. By default, Docker reads this file to automate the steps for creating a Docker image.

Basic Instructions:
- FROM: Specifies the base image. Every Dockerfile must start with a FROM instruction.
```
FROM ubuntu:20.04
```
- RUN: Executes commands in a new layer and commits the results. Commonly used to install software packages.
```
RUN apt-get update && apt-get install -y python3
```
- COPY: Copies files from the host machine into the Docker image.
```
COPY . /app
```
- WORKDIR: Sets the working directory for subsequent instructions.
```
WORKDIR /app
```
- CMD: Provides defaults for executing a container. The command will be executed when the container starts.
```
CMD ["python3", "app.py"]
```
- EXPOSE: Informs Docker that the container listens on the specified network ports at runtime.
```
EXPOSE 5000
```

Example Dockerfile:

# Use an official Python runtime as a parent image
FROM python:3.8-slim-buster

# Set the working directory in the container
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"]

Best Practices for Writing Dockerfiles

Use Official Base Images:
- Start with official images whenever possible. They are well-maintained and secure.
```
FROM python:3.8-slim-buster
```

Minimize Layers:

Combine multiple RUN commands into a single command to reduce the number of layers.

RUN apt-get update && apt-get install -y \
    package1 \
    package2 && \
    rm -rf /var/lib/apt/lists/*

Leverage Caching:
- Place instructions that change less frequently at the top of the Dockerfile to take advantage of layer caching.
```
COPY requirements.txt /app/
RUN pip install --no-cache-dir -r /app/requirements.txt
```
Use .dockerignore File:
- Similar to .gitignore, this file tells Docker which files and directories to ignore when building an image. This reduces the image size and build time.
```
.git
node_modules
Dockerfile
.dockerignore
```

Keep Images Small:

Remove unnecessary packages and files to minimize the image size.

RUN apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
    package1 \
    package2

Use Multi-Stage Builds:

Multi-stage builds allow you to use multiple FROM statements in your Dockerfile, reducing the final image size by copying only the necessary artifacts.

# Builder stage
FROM golang:1.16 as builder
WORKDIR /app
COPY . .
RUN go build -o myapp

# Final stage
FROM alpine:latest
COPY --from=builder /app/myapp /app/myapp
CMD ["/app/myapp"]

Specify Explicit Versions:
- Use specific versions of base images, dependencies, and packages to ensure consistency and avoid unexpected changes.
```
FROM python:3.8.5-slim-buster
```

Docker Containers

Running Containers

Running containers is the primary way to use Docker images. You create and start a container from an image using the docker run command.

Basic Command:
- The docker run command creates and starts a container from a specified image.
- Basic syntax: docker run [OPTIONS] IMAGE [COMMAND] [ARG...]
- Example: docker run -d --name mycontainer nginx
  - -d: Run the container in detached mode (in the background).
  - --name: Assign a name to the container.
  - nginx: The image to use.
Common Options:
- -p: Map container ports to host ports.
```
docker run -d -p 8080:80 nginx
```
- -v: Mount host directories or volumes into the container.
```
docker run -d -v /host/path:/container/path nginx
```
- -e: Set environment variables in the container.
```
docker run -d -e MY_ENV_VAR=value nginx
```
Interactive Containers:
- Running a container interactively using the -it option.
```
docker run -it ubuntu /bin/bash
```
- -i: Keep STDIN open even if not attached.
- -t: Allocate a pseudo-TTY (terminal).

Managing Containers

Managing containers involves starting, stopping, restarting, and removing them. Docker provides various commands to handle these operations.

Starting a Container:
- Use the docker start command to start a stopped container.
```
docker start mycontainer
```
Stopping a Container:
- Use the docker stop command to stop a running container.
```
docker stop mycontainer
```
Restarting a Container:
- Use the docker restart command to restart a container.
```
docker restart mycontainer
```
Removing a Container:
- Use the docker rm command to remove a stopped container.
```
docker rm mycontainer
```
- To forcefully remove a running container, use the -f option.
```
docker rm -f mycontainer
```
Listing Containers:
- Use the docker ps command to list running containers.
```
docker ps
```
- Use the -a option to list all containers, including stopped ones.
```
docker ps -a
```
Viewing Logs:
- Use the docker logs command to view the logs of a container.
```
docker logs mycontainer
```

Container Lifecycle

The container lifecycle includes the various states a container can be in, from creation to removal. Understanding these states helps in managing containers effectively.

Created:
- The container has been created but not started.
- Achieved with the docker create command.
```
docker create --name mycontainer nginx
```
Running:
- The container is actively running.
- Achieved with the docker run or docker start commands.
Paused:
- The container’s processes are paused.
- Achieved with the docker pause command.
```
docker pause mycontainer
```
- Resumed with the docker unpause command.
```
docker unpause mycontainer
```
Stopped:
- The container is not running but still exists.
- Achieved with the docker stop command.
Exited:
- The container has stopped running, either due to a user command or a process termination.
- Achieved when a container’s main process exits.
Dead:
- The container failed to stop properly and needs manual intervention.
- Requires investigation and cleanup.
Removed:
- The container has been deleted and no longer exists.
- Achieved with the docker rm command.

Example Workflow

Create and Start a Container:

docker run -d --name webserver -p 8080:80 nginx

Check Running Containers:
```
docker ps
```
Stop the Container:
```
docker stop webserver
```
Start the Container Again:
```
docker start webserver
```
Remove the Container:
```
docker rm webserver
```

Docker Networking

Docker networking allows containers to communicate with each other and with the outside world. Docker provides several networking drivers to manage container networks, each with different characteristics and use cases.

Bridge Networks
- The default network type for Docker containers.
- Containers on the same bridge network can communicate with each other using IP addresses or container names.
- Ideal for simple use cases where containers need to communicate on the same host.
Host Networks
- Removes network isolation between the Docker host and Docker containers.
- Containers share the host’s network stack and can directly access network interfaces.
- Provides better performance for network-intensive applications but lacks isolation.
Overlay Networks
- Used for multi-host networking.
- Allows containers running on different Docker hosts to communicate securely.
- Requires a key-value store (like etcd or Consul) to maintain network state across hosts.
- Commonly used in Docker Swarm and other orchestrators.
Macvlan Networks
- Allows containers to have their own MAC addresses, making them appear as physical devices on the network.
- Useful for applications that require direct network access, such as legacy systems.
None Network
- Disables all networking for a container.
- Useful for containers that do not need network access.

Docker Networking Commands

Docker provides several commands to manage and inspect networks. These commands allow you to create, inspect, and manage networks for your containers.

Listing Networks:
- Use the docker network ls command to list all networks.
```
docker network ls
```
Creating Networks:
- Use the docker network create command to create a custom network.
  - Example for a bridge network:
    docker network create my_bridge_network
  - Example for an overlay network:
    docker network create --driver overlay my_overlay_network
Inspecting Networks:
- Use the docker network inspect command to get detailed information about a network.
```
docker network inspect my_bridge_network
```
Connecting a Container to a Network:
- Use the docker network connect command to connect a container to a network.
```
docker network connect my_bridge_network mycontainer
```
Disconnecting a Container from a Network:
- Use the docker network disconnect command to disconnect a container from a network.
```
docker network disconnect my_bridge_network mycontainer
```
Removing Networks:
- Use the docker network rm command to remove a network.
```
docker network rm my_bridge_network
```

Detailed Breakdown

Bridge Networks

Default Network:
- When you start a container without specifying a network, it connects to the default bridge network.
- Example:
```
docker run -d --name container1 nginx
```

Custom Bridge Network:

Creating a custom bridge network allows for better control and organization.

docker network create my_bridge_network
docker run -d --name container2 --network my_bridge_network nginx

Communication:
- Containers on the same bridge network can communicate via container name or IP address.
```
docker exec -it container2 ping container1
```

Host Networks

Usage:
- Containers use the host’s network stack directly.
- Example:
```
docker run -d --name host_container --network host nginx
```
Performance:
- Provides high performance for network-intensive applications.
- Example:
```
docker run -d --network host --name fast_network_app my_network_app
```
No Isolation:
- Containers are not isolated from the host network.
- Use cases: High-performance applications, containers requiring direct network access.

Overlay Networks

Multi-Host Networking:
- Allows containers on different hosts to communicate securely.
- Requires a Docker Swarm or similar orchestrator.

Creating an Overlay Network:

Example:

docker network create --driver overlay my_overlay_network

Usage in Swarm:

Deploy services in a Swarm cluster using the overlay network.

docker service create --name web_service --network my_overlay_network nginx

Macvlan Networks

Direct Network Access:

Containers get their own MAC address.

Example:

docker network create -d macvlan \
  --subnet=192.168.1.0/24 \
  --gateway=192.168.1.1 \
  -o parent=eth0 my_macvlan_network

Use Cases:
- Applications needing direct access to the physical network, legacy systems.

None Network

No Networking:
- Completely disables networking for a container.
- Example:
```
docker run --network none --name isolated_container busybox
```

Example Workflow

Create a Custom Bridge Network:
```
docker network create my_custom_bridge
```

Run Containers on the Custom Network:

docker run -d --name container1 --network my_custom_bridge nginx
docker run -d --name container2 --network my_custom_bridge httpd

Inspect the Network:

docker network inspect my_custom_bridge

Connect Another Container to the Network:

docker run -d --name container3 alpine
docker network connect my_custom_bridge container3

Ping Between Containers:

docker exec -it container3 ping container1

Remove the Network:
```
docker network rm my_custom_bridge
```

Docker Storage

Volumes

Volumes are the preferred mechanism for persisting data generated and used by Docker containers. They are managed by Docker and can be used to share data between containers or between a container and the host system.

Creating and Managing Volumes:

Creating a Volume:
```
docker volume create my_volume
```
Listing Volumes:
```
docker volume ls
```
Inspecting a Volume:
```
docker volume inspect my_volume
```
Removing a Volume:
```
docker volume rm my_volume
```

Using Volumes:

To mount a volume into a container, use the -v or --mount option.

docker run -d --name my_container -v my_volume:/data nginx

Example using the --mount option:

docker run -d --name my_container --mount source=my_volume,target=/data nginx

Bind Mounts

Bind mounts allow you to mount a directory or file from the host filesystem into a container. Unlike volumes, bind mounts are not managed by Docker and provide more flexibility at the cost of portability.

Using Bind Mounts:

To use a bind mount, specify the path to the host directory and the container directory.
```
docker run -d --name my_container -v /host/path:/container/path nginx
```

Example using the --mount option:

docker run -d --name my_container --mount type=bind,source=/host/path,target=/container/path nginx

Data Persistence

Persisting data in Docker containers ensures that data is not lost when containers are stopped or removed. There are several strategies for managing data persistence in Docker.

Data Management in Docker:
- Volumes: Use volumes for storing persistent data. Volumes are managed by Docker and provide an easy way to persist and share data.
```
docker run -d --name my_container -v my_volume:/data nginx
```
- Bind Mounts: Use bind mounts for advanced use cases where you need to share specific directories or files between the host and the container.
```
docker run -d --name my_container -v /host/path:/container/path nginx
```
Backing Up and Restoring Data:
- Backing Up a Volume:
  - Use the docker run command to create a backup of a volume by copying its contents to a tar file.
    docker run --rm -v my_volume:/data -v /host/backup:/backup busybox tar cvf /backup/my_volume_backup.tar /data
- Restoring a Volume:
  - Use the docker run command to restore a volume from a tar file by copying its contents to the volume.
    docker run --rm -v my_volume:/data -v /host/backup:/backup busybox tar xvf /backup/my_volume_backup.tar -C /data

Detailed Breakdown

Creating and Managing Volumes

Creating a Volume:
- Volumes are created using the docker volume create command. This command creates a new volume that can be used by containers.
```
docker volume create my_volume
```
Inspecting a Volume:
- Use the docker volume inspect command to get detailed information about a volume, including its mount point on the host system.
```
docker volume inspect my_volume
```
Removing a Volume:
- Use the docker volume rm command to remove a volume. Note that you cannot remove a volume that is in use by a container.
```
docker volume rm my_volume
```

Binding Mounts

Creating a Bind Mount:
- Bind mounts are created by specifying the host directory and the container directory using the -v or --mount option.
```
docker run -d --name my_container -v /host/path:/container/path nginx
```
- The --mount option provides a more verbose syntax for bind mounts.
```
docker run -d --name my_container --mount type=bind,source=/host/path,target=/container/path nginx
```
Use Cases:
- Bind mounts are useful for scenarios where you need to share configuration files, logs, or other data between the host and the container.

Data Management in Docker

Using Volumes for Data Persistence:
- Volumes are the recommended way to persist data in Docker. They are easy to use, managed by Docker, and can be shared between containers.
```
docker run -d --name my_container -v my_volume:/data nginx
```
Advanced Use Cases with Bind Mounts:
- Bind mounts provide flexibility for advanced use cases but are less portable than volumes. They are useful for sharing specific host directories or files with containers.
```
docker run -d --name my_container -v /host/path:/container/path nginx
```

Backing Up and Restoring Data

Backing Up a Volume:

Use a temporary container to create a backup of a volume by copying its contents to a tar file.

docker run --rm -v my_volume:/data -v /host/backup:/backup busybox tar cvf /backup/my_volume_backup.tar /data

Restoring a Volume:

Use a temporary container to restore a volume from a tar file by copying its contents to the volume.

docker run --rm -v my_volume:/data -v /host/backup:/backup busybox tar xvf /backup/my_volume_backup.tar -C /data

Example Workflow

Create a Volume:
```
docker volume create my_data_volume
```

Run a Container with the Volume:

docker run -d --name my_app -v my_data_volume:/app/data nginx

List Volumes:
```
docker volume ls
```
Inspect the Volume:
```
docker volume inspect my_data_volume
```

Back Up the Volume:

docker run --rm -v my_data_volume:/data -v /host/backup:/backup busybox tar cvf /backup/my_data_backup.tar /data

Restore the Volume:

docker run --rm -v my_data_volume:/data -v /host/backup:/backup busybox tar xvf /backup/my_data_backup.tar -C /data

Docker Compose

Docker Compose is a tool for defining and running multi-container Docker applications. It uses a YAML file to configure the application’s services, networks, and volumes, making it easy to manage complex applications with multiple interconnected containers.

Defining Multi-Container Applications:
- Docker Compose allows you to define a multi-container application with all its dependencies in a single docker-compose.yml file.
- Each container in the application is defined as a service within this file, specifying its image, environment variables, ports, volumes, and network settings.
- Docker Compose manages the lifecycle of the entire application, ensuring that the services start in the correct order and with the necessary configurations.
Docker Compose YAML File:
- The docker-compose.yml file is the core configuration file used by Docker Compose.
- It defines all the services, networks, and volumes required for the application.
  Key Sections of a Docker Compose File
version:
- Specifies the version of the Docker Compose file format.
- Example:
```
version: '3.8'
```

services:

Defines the individual services (containers) that make up the application.

Example:

services:
  web:
    image: nginx
    ports:
      - "80:80"
  db:
    image: postgres
    environment:
      POSTGRES_DB: exampledb
      POSTGRES_USER: exampleuser
      POSTGRES_PASSWORD: examplepass

networks:
- Defines custom networks for the services to communicate.
- Example:
```
networks:
  frontend:
  backend:
```
volumes:
- Defines persistent storage for the services.
- Example:
```
volumes:
  db_data:
```

Example Docker Compose File

version: '3.8'

services:
  web:
    image: nginx
    ports:
      - "80:80"
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf
    networks:
      - frontend

  db:
    image: postgres
    environment:
      POSTGRES_DB: exampledb
      POSTGRES_USER: exampleuser
      POSTGRES_PASSWORD: examplepass
    volumes:
      - db_data:/var/lib/postgresql/data
    networks:
      - backend

networks:
  frontend:
  backend:

volumes:
  db_data:

Using Docker Compose

Starting the Application:
- Use the docker-compose up command to start the application.
```
docker-compose up
```
Stopping the Application:
- Use the docker-compose down command to stop the application and remove the containers.
```
docker-compose down
```
Running in Detached Mode:
- Use the -d flag with docker-compose up to run the containers in the background.
```
docker-compose up -d
```
Viewing Logs:
- Use the docker-compose logs command to view the logs of the running services.
```
docker-compose logs
```
Executing Commands in a Service:
- Use the docker-compose exec command to execute commands in a running service.
```
docker-compose exec web bash
```

Example Workflow

Create a Docker Compose File:

Save the following content to a file named docker-compose.yml:

version: '3.8'

services:
  web:
    image: nginx
    ports:
      - "80:80"
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf
    networks:
      - frontend

  db:
    image: postgres
    environment:
      POSTGRES_DB: exampledb
      POSTGRES_USER: exampleuser
      POSTGRES_PASSWORD: examplepass
    volumes:
      - db_data:/var/lib/postgresql/data
    networks:
      - backend

networks:
  frontend:
  backend:

volumes:
  db_data:

Start the Application:
- Run the following command to start the application:
```
docker-compose up -d
```
Check the Running Services:
- Use the following command to list the running services:
```
docker-compose ps
```
View Logs:
- Use the following command to view the logs of the web service:
```
docker-compose logs web
```
Stop the Application:
- Run the following command to stop and remove the containers:
```
docker-compose down
```

Managing Services with Docker Compose

Commands and Usage

Docker Compose provides a variety of commands to manage multi-container applications. Here are some of the essential commands and their usage:

Starting Services:
- docker-compose up:
  - Starts the services defined in the docker-compose.yml file.
    docker-compose up
- To run the services in detached mode (in the background), use the -d flag.
```
docker-compose up -d
```
Stopping Services:
- docker-compose down:
  - Stops the services and removes the containers, networks, and volumes created by up.
    docker-compose down
Viewing Service Logs:
- docker-compose logs:
  - Displays the logs from the services.
    docker-compose logs
- To view logs for a specific service, specify the service name.
```
docker-compose logs web
```
Listing Running Services:
- docker-compose ps:
  - Lists the containers running as part of the application.
    docker-compose ps
Scaling Services:
- docker-compose scale:
  - Scales a service to the specified number of instances.
    docker-compose scale web=3
- Note: In newer versions, use the --scale flag with up.
```
docker-compose up -d --scale web=3
```
Executing Commands in Running Containers:
- docker-compose exec:
  - Executes a command in a running container.
    docker-compose exec web bash
Building Services:
- docker-compose build:
  - Builds or rebuilds the services defined in the docker-compose.yml file.
    docker-compose build
Pulling Service Images:
- docker-compose pull:
  - Pulls the service images from a registry.
    docker-compose pull
Stopping Containers:
- docker-compose stop:
  - Stops the running containers without removing them.
    docker-compose stop
Removing Containers:
- docker-compose rm:
  - Removes stopped service containers.
    docker-compose rm

Environment Variables in Compose

Environment variables can be used to customize service configuration and control various aspects of the application’s behavior.

Defining Environment Variables:

Environment variables can be defined directly in the docker-compose.yml file under the environment key.

services:
  web:
    image: nginx
    environment:
      - NGINX_HOST=localhost
      - NGINX_PORT=80

Using .env File:
- Environment variables can also be defined in a .env file in the same directory as the docker-compose.yml file. Docker Compose automatically reads this file.
```
NGINX_HOST=localhost
NGINX_PORT=80
```
- Reference these variables in the docker-compose.yml file using the ${VARIABLE_NAME} syntax.
```
services:
  web:
    image: nginx
    environment:
      - NGINX_HOST=${NGINX_HOST}
      - NGINX_PORT=${NGINX_PORT}
```
Passing Environment Variables from the Host:
- Use the --env-file option with docker-compose commands to specify a file containing environment variables.
```
docker-compose --env-file ./custom.env up
```

Networking with Compose

Docker Compose provides powerful networking capabilities to define and manage communication between services.

Default Network:
- By default, Docker Compose creates a single network for all services defined in the docker-compose.yml file. Services can communicate with each other using their service names as hostnames.

Custom Networks:

You can define custom networks to control the communication between services more granularly.

networks:
  frontend:
  backend:
     
services:
  web:
    image: nginx
    networks:
      - frontend
     
  db:
    image: postgres
    networks:
      - backend

Network Aliases:

Assign network aliases to services for easier communication.

services:
  web:
    image: nginx
    networks:
      frontend:
        aliases:
          - webserver
     
  db:
    image: postgres
    networks:
      backend:
        aliases:
          - database

Network Modes:

Specify network modes for services, such as bridge, host, none, or custom networks.

services:
  web:
    image: nginx
    network_mode: bridge
     
  db:
    image: postgres
    network_mode: host

Example Workflow

Define a docker-compose.yml File:

version: '3.8'

services:
  web:
    image: nginx
    ports:
      - "80:80"
    networks:
      - frontend
    environment:
      - NGINX_HOST=${NGINX_HOST}
      - NGINX_PORT=${NGINX_PORT}

  db:
    image: postgres
    environment:
      POSTGRES_DB: exampledb
      POSTGRES_USER: exampleuser
      POSTGRES_PASSWORD: examplepass
    volumes:
      - db_data:/var/lib/postgresql/data
    networks:
      - backend

networks:
  frontend:
  backend:

volumes:
  db_data:

Create an .env File:
```
NGINX_HOST=localhost
NGINX_PORT=80
```
Start the Application:
```
docker-compose up -d
```
Check the Running Services:
```
docker-compose ps
```
View Logs:
```
docker-compose logs
```
Execute a Command in the Web Service:
```
docker-compose exec web bash
```
Stop and Remove the Services:
```
docker-compose down
```

Docker Hub and Registry

Docker Hub

Docker Hub is a cloud-based repository where you can find, share, and store container images. It provides a centralized resource for container image discovery, distribution, and management.

Pulling and Pushing Images

Pulling Images:
- Docker Hub hosts a vast collection of pre-built images that you can use in your projects. To use an image, you need to pull it from Docker Hub.
- The docker pull command is used to download an image from Docker Hub.
```
docker pull <image-name>
```
- Example:
```
docker pull nginx
```
Pushing Images:
- You can push your own images to Docker Hub to share them with others or to use them across different environments.
- To push an image, you need to tag it with your Docker Hub username and repository name, then use the docker push command.
```
docker tag <local-image> <username>/<repository>:<tag>
docker push <username>/<repository>:<tag>
```
- Example:
```
docker tag myapp:latest mouhamaddev/myapp:latest
docker push mouhamaddev/myapp:latest
```

Using Public and Private Repositories

Public Repositories:
- Public repositories are accessible by anyone. They are ideal for sharing open-source projects or public resources.
- When you push an image to a public repository, it can be pulled by any user without authentication.
Private Repositories:
- Private repositories restrict access to only those users or teams you specify. They are ideal for proprietary or sensitive projects.
- To create a private repository, you need a Docker Hub account with a paid plan that supports private repositories.
Creating a Repository:
- Log in to Docker Hub and navigate to your profile.
- Click on “Create Repository”.
- Enter the repository name, description, and choose whether it should be public or private.
- Click “Create”.
Logging In:
- Before you can push or pull from a private repository, you need to log in to Docker Hub from your command line using docker login.
```
docker login
```
- You will be prompted to enter your Docker Hub username and password.
Managing Access:
- For private repositories, you can manage access permissions by inviting other users or teams.
- Navigate to your repository settings on Docker Hub, and under “Collaborators”, add the usernames or teams you want to grant access to.

Example Workflow

Pull an Image from Docker Hub:
```
docker pull nginx
```

Tag and Push a Custom Image:

docker tag myapp:latest mouhamaddev/myapp:latest
docker push mouhamaddev/myapp:latest

Create a Private Repository on Docker Hub:
- Log in to Docker Hub.
- Click “Create Repository”.
- Name the repository, add a description, and select “Private”.
- Click “Create”.
Push an Image to the Private Repository:
- Tag the image with the repository name.
```
docker tag myapp:latest mouhamaddev/private-repo:latest
```
- Log in to Docker Hub from the command line.
```
docker login
```
- Push the image to the private repository.
```
docker push mouhamaddev/private-repo:latest
```
Pull an Image from the Private Repository:
- Ensure you are logged in to Docker Hub.
- Pull the image using the repository name.
```
docker pull mouhamaddev/private-repo:latest
```

Private Docker Registries

Setting Up a Private Registry

A private Docker registry allows you to host your own images securely, providing control over who can access and interact with them. Here’s how to set up a private Docker registry:

Running a Registry Container:
- Docker provides an official registry image that you can use to run a private registry.
- To start a basic registry, use the following command:
```
docker run -d -p 5000:5000 --name registry registry:2
```
Tagging and Pushing an Image to the Private Registry:
- Tag the image to point to your registry. For example, if your registry is running on localhost:5000:
```
docker tag myapp:latest localhost:5000/myapp:latest
```
- Push the image to your private registry:
```
docker push localhost:5000/myapp:latest
```
Pulling an Image from the Private Registry:
- To pull the image from your private registry, use the following command:
```
docker pull localhost:5000/myapp:latest
```

Configuring and Managing a Registry

Once the registry is running, you can configure and manage it to meet your requirements.

Configuration Options:
- The Docker registry can be configured using a config.yml file. You can specify various options such as storage backend, authentication, and TLS settings.
- To use a custom configuration file, mount it as a volume:
```
docker run -d -p 5000:5000 --name registry -v /path/to/config.yml:/etc/docker/registry/config.yml registry:2
```

Enabling HTTPS:

For security, it’s recommended to run your registry over HTTPS. You can use self-signed certificates or certificates from a trusted CA.

Generate self-signed certificates (for example, using OpenSSL):

mkdir -p certs
openssl req -newkey rsa:4096 -nodes -sha256 -keyout certs/domain.key -x509 -days 365 -out certs/domain.crt

Run the registry with the certificates:

docker run -d -p 5000:5000 --name registry \
  -v /path/to/certs:/certs \
  -e REGISTRY_HTTP_TLS_CERTIFICATE=/certs/domain.crt \
  -e REGISTRY_HTTP_TLS_KEY=/certs/domain.key \
  registry:2

Authentication and Authorization:

To restrict access, you can enable basic authentication using an .htpasswd file.

Install htpasswd utility and create the password file:

apt-get install apache2-utils
htpasswd -cB /path/to/auth/htpasswd myuser

Run the registry with authentication:

docker run -d -p 5000:5000 --name registry \
  -v /path/to/auth:/auth \
  -e "REGISTRY_AUTH=htpasswd" \
  -e "REGISTRY_AUTH_HTPASSWD_REALM=Registry Realm" \
  -e "REGISTRY_AUTH_HTPASSWD_PATH=/auth/htpasswd" \
  registry:2

Managing Storage:
- By default, the registry stores images on the local filesystem. You can configure it to use other storage backends like Amazon S3, Google Cloud Storage, or Azure Blob Storage.
- Example configuration for Amazon S3 in config.yml:
```
version: 0.1
storage:
  s3:
    accesskey: <your-access-key>
    secretkey: <your-secret-key>
    region: us-east-1
    bucket: <your-bucket-name>
```
Managing and Cleaning Up:
- Use the registry API to manage and clean up the registry.
- Example: List all repositories:
```
curl -X GET http://localhost:5000/v2/_catalog
```

Setting Up a Reverse Proxy:

It’s common to place a reverse proxy (e.g., Nginx) in front of the registry for additional features like load balancing, SSL termination, and more advanced authentication.

Example Nginx configuration:

server {
  listen 443 ssl;
  server_name myregistrydomain.com;

  ssl_certificate /etc/nginx/certs/domain.crt;
  ssl_certificate_key /etc/nginx/certs/domain.key;

  location / {
    proxy_pass http://localhost:5000;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
  }
}

Example Workflow

Run a Private Registry:

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

Tag and Push an Image:

docker tag myapp:latest localhost:5000/myapp:latest
docker push localhost:5000/myapp:latest

Pull an Image from the Private Registry:

docker pull localhost:5000/myapp:latest

Enable HTTPS:

Generate certificates and run the registry with TLS:

mkdir -p certs
openssl req -newkey rsa:4096 -nodes -sha256 -keyout certs/domain.key -x509 -days 365 -out certs/domain.crt
docker run -d -p 5000:5000 --name registry \
  -v $(pwd)/certs:/certs \
  -e REGISTRY_HTTP_TLS_CERTIFICATE=/certs/domain.crt \
  -e REGISTRY_HTTP_TLS_KEY=/certs/domain.key \
  registry:2

Set Up Authentication:

Create an .htpasswd file and run the registry with authentication:

apt-get install apache2-utils
htpasswd -cB /path/to/auth/htpasswd myuser
docker run -d -p 5000:5000 --name registry \
  -v /path/to/auth:/auth \
  -e "REGISTRY_AUTH=htpasswd" \
  -e "REGISTRY_AUTH_HTPASSWD_REALM=Registry Realm" \
  -e "REGISTRY_AUTH_HTPASSWD_PATH=/auth/htpasswd" \
  registry:2

Advanced Docker Topics

Docker Swarm

Docker Swarm is Docker’s native clustering and orchestration tool, allowing you to manage a cluster of Docker nodes as a single virtual system. It enables you to deploy and manage multi-container applications across multiple Docker hosts.

Introduction to Orchestration

Orchestration involves automating the deployment, scaling, and management of containerized applications. Docker Swarm provides built-in orchestration capabilities, allowing you to:

Scale applications: Increase or decrease the number of container instances running your application.
Load balancing: Distribute incoming traffic across multiple container instances.
Fault tolerance: Automatically recover from failures and ensure high availability.

Creating and Managing Swarms

Initializing a Swarm:
- To create a new swarm, run the following command on the manager node:
```
docker swarm init
```
- This command outputs a join token that can be used to add worker nodes to the swarm.
Adding Nodes to the Swarm:
- On the worker nodes, use the join token to join the swarm:
```
docker swarm join --token <worker-token> <manager-ip>:2377
```
- To add another manager node, use the manager join token provided by the docker swarm init command.
Managing Nodes:
- List all nodes in the swarm:
```
docker node ls
```
- Promote a worker to a manager:
```
docker node promote <node-id>
```
- Demote a manager to a worker:
```
docker node demote <node-id>
```
Removing Nodes:
- To remove a node from the swarm, run the following on the manager node:
```
docker node rm <node-id>
```

Deploying Services in a Swarm

Creating a Service:
- Services are the core abstraction in Docker Swarm for running containers.
- To create a service, use the docker service create command:
```
docker service create --name <service-name> --replicas <number-of-replicas> <image>
```
- Example:
```
docker service create --name web --replicas 3 nginx
```
Listing Services:
- To list all services running in the swarm, use:
```
docker service ls
```
Inspecting a Service:
- To get detailed information about a service, use:
```
docker service inspect <service-name>
```

Updating a Service:

To update a service (e.g., changing the number of replicas or the image version), use:
```
docker service update --replicas <new-number-of-replicas> <service-name>
```
Example:
```
docker service update --replicas 5 web
```

Scaling a Service:
- Scaling a service involves changing the number of replicas running:
```
docker service scale <service-name>=<number-of-replicas>
```
- Example:
```
docker service scale web=10
```
Removing a Service:
- To remove a service from the swarm, use:
```
docker service rm <service-name>
```

Example Workflow

Initialize the Swarm:
```
docker swarm init
```

Join Worker Nodes:

On each worker node:

docker swarm join --token <worker-token> <manager-ip>:2377

Create and Deploy a Service:

docker service create --name web --replicas 3 nginx

Scale the Service:
```
docker service scale web=5
```

Update the Service:

docker service update --image nginx:latest web

Remove the Service:
```
docker service rm web
```

Docker Security

Securing Docker is crucial to protecting your containerized applications and the underlying host system. Docker provides several features and best practices to help you secure your containers and their interactions.

Best Practices for Securing Docker

Use Official and Trusted Images:
- Always use official images from Docker Hub or trusted sources. They are regularly maintained and scanned for vulnerabilities.
- Regularly update images to incorporate the latest security patches.
Minimize Image Size:
- Use minimal base images (e.g., alpine) to reduce the attack surface.
- Remove unnecessary packages and dependencies from images.
Run Containers with Least Privilege:
- Avoid running containers as the root user. Use the USER directive in your Dockerfile to specify a non-root user.
```
USER nonrootuser
```
- Use Docker’s --user flag to override the default user at runtime.
```
docker run --user nonrootuser myapp
```
Limit Container Capabilities:
- Use Docker’s security options to drop unnecessary capabilities.
```
docker run --cap-drop=ALL --cap-add=NET_ADMIN myapp
```
Use Network Isolation:
- Place containers on separate networks to limit communication between them.
- Use Docker’s built-in network features like bridge, overlay, or macvlan for isolation.
Enable Docker Content Trust:
- Ensure that Docker images are signed and verified before pulling by enabling content trust.
```
export DOCKER_CONTENT_TRUST=1
```
Regularly Scan Images for Vulnerabilities:
- Use tools like Docker Bench for Security or third-party solutions (e.g., Aqua Security, Clair) to scan images for vulnerabilities.
Implement Proper Logging and Monitoring:
- Enable logging to monitor container activity. Use tools like the ELK stack (Elasticsearch, Logstash, Kibana) or other monitoring solutions to collect and analyze logs.
Keep Docker and Host Systems Updated:
- Regularly update Docker to the latest version to benefit from security fixes and improvements.
- Ensure that the host operating system and any dependencies are up-to-date.

User Namespaces

User namespaces provide an additional layer of security by mapping container users to different users on the host system. This prevents container processes from having direct access to the host’s user and group IDs.

Enable User Namespaces:
- Modify Docker’s configuration file (/etc/docker/daemon.json) to enable user namespaces.
```
{
  "userns-remap": "default"
}
```
- Restart the Docker daemon for changes to take effect.
```
sudo systemctl restart docker
```
Understand the Mapping:
- When user namespaces are enabled, Docker maps container user IDs (UIDs) to different host UIDs, isolating container users from the host system.
- This mapping ensures that a container user with UID 0 (root) does not have root privileges on the host system.
Customize User Namespace Mapping:
- You can customize user namespace mappings by specifying a specific mapping in the configuration file.
```
{
  "userns-remap": "myuser"
}
```
- Create a user and group on the host to correspond with the container’s user namespace.

Secrets Management

Docker provides mechanisms to securely manage and distribute secrets, such as passwords and API keys, used by applications running in containers.

Creating Secrets:

Use Docker CLI to create secrets:

echo "mysecretpassword" | docker secret create my_secret -

Using Secrets in Services:
- To use secrets in Docker Swarm services, specify the secrets when creating or updating a service:
```
docker service create --name myservice --secret my_secret myimage
```
Accessing Secrets in Containers:
- Secrets are made available to containers as files in /run/secrets/.
- For example, to access my_secret:
```
cat /run/secrets/my_secret
```
Managing and Removing Secrets:
- List all secrets:
```
docker secret ls
```
- Remove a secret:
```
docker secret rm my_secret
```

Using Docker Compose for Secrets:

Define secrets in a docker-compose.yml file:

version: '3.8'
services:
  web:
    image: myimage
    secrets:
      - my_secret

secrets:
  my_secret:
    file: ./my_secret.txt

Deploy with Docker Compose:
```
docker-compose up
```

Example Workflow

Create and Use a Secret:

echo "mysecretpassword" | docker secret create my_secret -
docker service create --name myservice --secret my_secret myimage

Access the Secret in a Container:
- Inside the container:
```
cat /run/secrets/my_secret
```

Enable User Namespaces:

Edit daemon.json:
```
{
  "userns-remap": "default"
}
```
Restart Docker:
```
sudo systemctl restart docker
```

Docker in Production

Deploying Docker containers in production environments requires careful planning and implementation to ensure reliability, performance, and security. Here’s a guide to best practices, monitoring, logging, and performance tuning for Docker in production.

Best Practices

Use Multi-Stage Builds:
- Optimize your Dockerfile by using multi-stage builds to reduce the final image size. This involves creating intermediate images for building the application and then copying only the necessary artifacts to the final image. ```dockerfile
  Stage 1: Build
  
  FROM node:14 AS builder WORKDIR /app COPY package*.json ./ RUN npm install COPY . . RUN npm run build
Stage 2: Final

FROM nginx:alpine COPY –from=builder /app/build /usr/share/nginx/html ```
Implement Robust Health Checks:
- Define health checks in your Dockerfile or Docker Compose file to ensure that your containerized applications are running as expected.
```
HEALTHCHECK --interval=30s --timeout=10s --start-period=5s \
CMD curl -f http://localhost/ || exit 1
```
Use Docker Secrets and Configs:
- Manage sensitive data and configuration settings securely using Docker secrets and configs. Avoid hardcoding sensitive information in your images.
Configure Resource Limits:
- Set CPU and memory limits for your containers to prevent them from consuming excessive resources.
```
docker run --memory="500m" --cpus="1.0" myimage
```
Network Security:
- Use Docker’s network isolation features to segregate containers and limit access between them.
- Configure firewalls and security groups to control traffic to and from your Docker containers.
Automate Deployments:
- Use CI/CD pipelines to automate the build, test, and deployment processes. Integrate tools like Jenkins, GitLab CI, or GitHub Actions to streamline deployments.
Regular Updates and Patching:
- Regularly update Docker and container images to include the latest security patches and improvements.
Backup and Recovery:
- Implement backup strategies for important data and application states. Ensure you have a plan for recovering from failures.

Monitoring and Logging

Centralized Logging:
- Use centralized logging solutions to collect and aggregate logs from all containers. Tools like ELK Stack (Elasticsearch, Logstash, Kibana), Fluentd, or Graylog can help with this.
- Configure Docker to send logs to a central logging service:
```
docker run --log-driver=syslog myimage
```
Container Metrics:
- Monitor container metrics like CPU usage, memory consumption, and network I/O using tools such as Prometheus, Grafana, or Docker’s built-in stats command.
```
docker stats
```
Application Performance Monitoring (APM):
- Implement APM solutions (e.g., New Relic, Datadog) to monitor application performance, trace requests, and detect issues.
Alerting and Notifications:
- Set up alerts for critical metrics and events. Tools like Prometheus Alertmanager or Datadog can be configured to notify you of issues.
Health Checks and Uptime Monitoring:
- Continuously check the health and uptime of your services. Use tools like UptimeRobot or Pingdom for external monitoring.

Performance Tuning

Optimize Image Performance:
- Minimize image size by using lightweight base images and multi-stage builds.
- Use efficient image layers and avoid unnecessary layers in your Dockerfile.
Tune Docker Daemon Settings:
- Adjust Docker daemon settings for performance, such as increasing the number of concurrent downloads or optimizing storage driver settings.
```
dockerd --storage-driver=overlay2
```
Container Resource Allocation:
- Configure CPU and memory limits based on the application’s needs. Ensure containers have sufficient resources to operate efficiently.
```
docker run --memory="1g" --cpus="2.0" myapp
```
Use Overlay Networks Efficiently:
- For Docker Swarm or multi-host setups, use overlay networks to manage communication between containers across different hosts.
Optimize Disk I/O:
- Use appropriate storage drivers and optimize disk I/O performance. Consider using SSDs for better performance.
Regularly Review and Optimize Configuration:
- Periodically review your Docker configuration and application performance. Adjust settings and configurations based on observed performance and usage patterns.

Example Workflow

Build a Multi-Stage Dockerfile:

FROM node:14 AS builder
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build

FROM nginx:alpine
COPY --from=builder /app/build /usr/share/nginx/html

Set Resource Limits:

docker run --memory="512m" --cpus="1.0" myapp

Configure Centralized Logging:
```
docker run --log-driver=syslog myapp
```
Monitor Metrics:
```
docker stats
```
Set Up Alerts:
- Configure Prometheus Alertmanager or Datadog for monitoring and notifications.
Tune Docker Daemon:
```
dockerd --storage-driver=overlay2
```

Practical Exercises and Projects

Hands-on projects are essential for solidifying your Docker skills and understanding real-world applications. Here are some practical exercises and projects that will help you apply what you’ve learned:

Hands-On Projects

Building and Deploying a Web Application

Objective: Create a simple web application, containerize it with Docker, and deploy it to a local or cloud environment.

Steps:
- Create a Simple Web Application:
  - Choose a tech stack (e.g., Node.js with Express, Python with Flask, or Django).
  - Write a basic application with a simple endpoint that returns a “Hello, World!” message.
  - Example (Node.js with Express):
    // server.js const express = require('express'); const app = express(); const PORT = process.env.PORT || 3000; app.get('/', (req, res) => { res.send('Hello, World!'); }); app.listen(PORT, () => { console.log(`Server running on port ${PORT}`); });
- Write a Dockerfile:
  - Create a Dockerfile to build and run your web application.
  - Example (Node.js):
    # Use the official Node.js image FROM node:14 # Set the working directory WORKDIR /app # Copy application files COPY package*.json ./ RUN npm install COPY . . # Expose the port the app runs on EXPOSE 3000 # Run the application CMD ["node", "server.js"]
- Build and Run the Docker Image:
```
docker build -t my-web-app .
docker run -p 3000:3000 my-web-app
```
- Deploy to Cloud (Optional):
  - Use a platform like Heroku, AWS Elastic Beanstalk, or Google Cloud Run to deploy your Dockerized application.

Multi-Container Applications with Docker Compose

Objective: Create a multi-container application using Docker Compose to define and run multiple services (e.g., a web server and a database).

Steps:

Define Your Services:
- Create a simple application with a web service and a database service (e.g., a Flask app with a PostgreSQL database).

Write Dockerfiles for Each Service:

Web Service (Flask):

# Dockerfile for Flask App
FROM python:3.8

WORKDIR /app

COPY requirements.txt .
RUN pip install -r requirements.txt

COPY . .

EXPOSE 5000

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

Database Service (PostgreSQL):
- Use the official PostgreSQL image from Docker Hub.

Create a docker-compose.yml File:

version: '3.8'

services:
  web:
    build:
      context: ./web
    ports:
      - "5000:5000"
    depends_on:
      - db
    environment:
      - DATABASE_URL=postgresql://user:password@db/mydatabase

  db:
    image: postgres:13
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: password
      POSTGRES_DB: mydatabase
    volumes:
      - db_data:/var/lib/postgresql/data

volumes:
  db_data:

Run the Multi-Container Application:
```
docker-compose up
```
Access the Web Application:
- Open your browser and navigate to http://localhost:5000.

Setting Up a CI/CD Pipeline with Docker

Objective: Implement a CI/CD pipeline that automates the building, testing, and deployment of Dockerized applications.

Steps:
- Create a Git Repository:
  - Initialize a Git repository for your project.
- Write a Dockerfile for Your Application:
  - Use the same Dockerfile as in the previous projects.
- Set Up a CI/CD Tool:
  - Choose a CI/CD tool like GitHub Actions, GitLab CI, or Jenkins.
- Create CI/CD Pipeline Configuration:
  
  Example with GitHub Actions:
  - Create a .github/workflows/ci-cd.yml file:
    name: CI/CD Pipeline on: push: branches: - main jobs: build: runs-on: ubuntu-latest steps: - name: Checkout code uses: actions/checkout@v2 - name: Set up Docker Buildx uses: docker/setup-buildx-action@v2 - name: Build Docker image run: | docker build -t my-web-app . - name: Run tests run: | docker run my-web-app npm test - name: Push Docker image run: | docker tag my-web-app mydockerhubusername/my-web-app:latest echo "$" | docker login -u "$" --password-stdin docker push mydockerhubusername/my-web-app:latest
- Configure Deployment:
  - Add deployment steps to your CI/CD pipeline to deploy your Dockerized application to a cloud provider or a production server.
- Test Your Pipeline:
  - Push changes to your Git repository and verify that the CI/CD pipeline runs as expected, building, testing, and deploying your application.

Example Workflow

Build and Deploy a Web Application:
- Create a simple web app, Dockerize it, and deploy it locally or to the cloud.
Multi-Container Application with Docker Compose:
- Define and run a web service and a database service using Docker Compose.
CI/CD Pipeline Setup:
- Automate the build, test, and deployment processes using a CI/CD tool like GitHub Actions.

Code-Memo

Docker

Docker Architecture

Docker Engine

Docker Daemon (dockerd)

Docker Client (docker)

Docker Images

Docker Containers

Example Workflow

Docker Images

Creating Images

Using Dockerfile

Best Practices for Writing Dockerfiles

Docker Containers

Running Containers

Managing Containers

Container Lifecycle

Example Workflow

Docker Networking

Docker Networking Commands

Detailed Breakdown

Bridge Networks

Host Networks

Overlay Networks

Macvlan Networks

None Network

Example Workflow

Docker Storage

Volumes

Bind Mounts

Data Persistence

Detailed Breakdown

Creating and Managing Volumes

Binding Mounts

Data Management in Docker

Backing Up and Restoring Data

Example Workflow

Docker Compose

Key Sections of a Docker Compose File

Example Docker Compose File

Using Docker Compose

Example Workflow

Managing Services with Docker Compose

Commands and Usage

Environment Variables in Compose

Networking with Compose

Example Workflow

Docker Hub and Registry

Docker Hub

Pulling and Pushing Images

Using Public and Private Repositories

Example Workflow

Private Docker Registries

Setting Up a Private Registry

Configuring and Managing a Registry

Example Workflow

Advanced Docker Topics

Docker Swarm

Introduction to Orchestration

Creating and Managing Swarms

Deploying Services in a Swarm

Example Workflow

Docker Security

Best Practices for Securing Docker

User Namespaces

Secrets Management

Example Workflow

Docker in Production

Best Practices

Stage 1: Build

Stage 2: Final

Monitoring and Logging

Performance Tuning

Example Workflow

Practical Exercises and Projects

Hands-On Projects

Example Workflow

Docker Daemon (`dockerd`)

Docker Client (`docker`)