There is arguably not a more familiar name with containerized technology than Docker. With its ability to streamline operations and optimize resources, Docker has shifted the paradigm from traditional virtual machines to containers.
It has continued to evolve to enhance user-friendly features and functionalities, making it an ideal platform for managing Continuous Integration and Continuous Delivery (CI/CD) systems, driving software development, and deployment efficiency. Understanding the basics when working with Docker is important. Let’s look at the best Docker containers commands you need to know to master working with Docker.
Docker in the home lab
I run Docker containers in the home lab extensively as it allows one of the easiest ways to spin up new services and run solutions in the home lab. With Docker, you don’t have to worry about installing all the underlying prerequisites and technologies. These are contained in the image itself.
Docker doesn’t replace virtual machines entirely. Rather it allows you to run a much more efficient data center since you can use VMs for container hosts, then use containers to run your applications. Instead of having a separate virtual machine for each application as we used to configure.
Docker Images and Docker Containers
Understanding Docker begins with grasping two key components – Docker images and Docker containers. A Docker image, essentially a read-only template, encapsulates the instructions needed to spawn a Docker container. Contrastingly, a Docker container represents a running instance of an image, housing all the necessary components to run an application.
Docker images find their home in a Docker registry like Docker Hub. This service functions as a warehouse for pre-built images for web apps like Nginx, Apache, Memcached (a distributed memory caching system) and as a platform for users to share their custom Docker images.
Docker containers are the constructs where Docker images are run on a Docker container host, using the Docker runtime.
As developers continually strive for optimization, “best Docker images” and “best Docker containers” often crop up in discussions, highlighting the demand for high-quality, performance-oriented Docker resources.
Docker Images: The Building Blocks for Successful Docker Projects
At the heart of every Docker project are Docker images. Developers can generate Docker images using a Dockerfile, a textual document containing commands for building an image. Upon preparing the Dockerfile, the docker build command comes into play, creating the Docker image.
Below is a simple example of a Dockerfile used to build an Ubuntu 22.04 container:
FROM ubuntu:22.04 ENV DEBIAN_FRONTEND=noninteractive RUN apt-get update ENTRYPOINT bash
A Docker image can package all required to run applications – code, a runtime, libraries, environment variables, and config files. This compact, all-inclusive structure makes Docker a perfect fit for Continuous Integration, offering a consistent and replicable software development environment.
Docker Compose: Orchestrating Multiple Containers Seamlessly
It is a crucial facet of the Docker project, significantly simplifying the definition and management of multi-container applications. Docker Compose makes complex applications more manageable by treating multiple containers as a single service.
Moreover, Docker Compose’s built-in support for managing networks and volumes offers greater flexibility to developers, fostering efficient deployment of multi-service applications. This powerful functionality solidifies Docker Compose’s position as a vital tool for developers and system administrators managing multiple containers.
Below is an example of a Docker compose file:
services: traefik2: image: traefik:latest restart: always command: - "--log.level=DEBUG" - "--api.insecure=true" - "--providers.docker=true" - "--providers.docker.exposedbydefault=true" - "--entrypoints.web.address=:80" - "--entrypoints.websecure.address=:443" - "--entrypoints.web.http.redirections.entryPoint.to=websecure" - "--entrypoints.web.http.redirections.entryPoint.scheme=https" ports: - 80:80 - 443:443 networks: - traefik volumes: - /var/run/docker.sock:/var/run/docker.sock container_name: traefik pihole: image: pihole/pihole:latest container_name: pihole ports: - "53:53/tcp" - "53:53/udp" dns: - 127.0.0.1 - 188.8.131.52 environment: TZ: 'America/Chicago' WEBPASSWORD: 'password' PIHOLE_DNS_: 184.108.40.206;220.127.116.11 DNSSEC: 'false' VIRTUAL_HOST: piholetest.cloud.local # Same as port traefik config WEBTHEME: default-dark PIHOLE_DOMAIN: lan volumes: - '~/pihole/pihole:/etc/pihole/' - '~/pihole/dnsmasq.d:/etc/dnsmasq.d/' restart: always networks: - traefik labels: - traefik.enable=true - traefik.http.routers.pihole.rule=Host(`piholetest.cloud.local`) - traefik.http.routers.pihole.tls=true - traefik.http.routers.pihole.entrypoints=websecure - traefik.http.services.pihole.loadbalancer.server.port=80 networks: traefik: driver: bridge name: traefik ipam: driver: default
Docker in Production: Managing Real-world Challenges
The power of Docker extends beyond development environments. Maintaining a constant vigil on containers to promptly identify bugs in a production environment is paramount. Tools like Docker Mon provide critical insights into Docker containers’ performance and resource usage, enabling effective container management.
In larger setups, managing containers spread across multiple servers or clusters necessitates Container Orchestration tools like Kubernetes. Such tools are invaluable for keeping a distributed system of containers functioning smoothly and efficiently.
The Role of Third-Party Docker Images
While developing custom Docker images is routine, there are instances where employing third-party Docker images from Docker Hub is more time-efficient and practical. For example, Passenger Docker provides a robust set of defaults for running Ruby, Python, Node.js, and Meteor web applications.
However, caution should prevail when using third-party images. Always ensure they originate from trusted sources, and scrutinize the Dockerfile to understand what’s included in the image.
Docker and Web Applications: A Perfect Match
Docker has revolutionized the deployment landscape for web applications. Whether it’s a standalone web server or a composite application with multiple services like a database, cache, and web UI, Docker can manage it all effortlessly.
Docker images, tailored for each service, can be governed using Docker Compose, ensuring a uniform application operation. This eliminates the notorious “it works on my machine” syndrome, rendering Docker an ideal tool for consistent software development and deployment.
Best Docker Commands to know
The process to manage Docker containers and container images in your environment can easily be done with the following 10 commands. While there are open source user interface solutions you can use, knowing the Docker command line is definitely beneficial.
docker pull: Fetches Docker images (docker apps) from Docker Hub or other Docker registries.
docker run: Creates a new container from an image and initiates it.
docker stop: Halts a running container.
docker start: Powers up a halted container.
docker restart: Resets a running or halted container.
docker rm: Deletes a Docker container.
docker logs: Retrieves the logs of a Docker container.
docker stats: Provides live data about running containers.
docker volume: Manage containers volumes associated with containers.
docker network: Handles networking aspects of Docker containers.
These commands are integral to managing Docker containers, whether you are using Docker containers in the home lab or in the enterprise. Even if you use the best Docker apps, you will undoubtedly need to manage the container and image using the following commands.
The docker pull command fetches Docker images from Docker Hub or other Docker registries. It uses the base image to create the container.
docker pull ubuntu:22.04
This command downloads the Ubuntu 22.04 image.
The docker run command creates and runs a new container from an image.
docker run -d -p 80:80 --name <name your container> nginx:latest
This command starts an Nginx server container named “my_server” in detached mode. Also, be sure to adjust the external port if needed to avoid conflicts.
The docker stop command halts a running container.
docker stop <your container name>
This command stops the “my_server” container.
The docker start command powers up a halted container.
docker start <your container name>
This command restarts the “my_server” container.
The docker restart command resets a container.
docker restart <your container name>
This command restarts the “my_server” container.
The docker rm command removes a Docker container.
docker rm <your container name>
This command removes the “my_server” container.
The docker logs command fetches the logs of a Docker container.
docker logs <your container name>
This command retrieves logs of the “my_server” container.
The docker stats command provides live data about running containers.
docker stats <your container name>
This command shows live data stream for “my_server” container.
The docker volume command manages the volumes tied to Docker containers.
docker volume create <volume name>
This command creates a new volume named “my_volume.”
The docker network command handles networking aspects of Docker containers.
docker network create <network name>
This command creates a new network named “my_network.”
Best Docker containers for your Synology
Frequently Asked Questions
1. What Makes Docker an Ideal Platform for Running Web Applications?
Docker provides a consistent environment across development and production stages, making it the ideal platform for running web applications. It also simplifies the management of environment variables and configurations, ensuring a smoother deployment process.
Additionally, using Docker Compose, managing multiple containers that form a complex web application becomes a breeze.
2. Can Docker Be Used for Personal Use, Such as a Home Server Setup?
Absolutely! Docker’s flexibility makes it a great tool for setting up home servers. You can run various services, like media servers, download clients, and home automation tools, each in its own container, ensuring they don’t interfere with each other.
Docker’s ability to restart containers automatically if they crash also makes it ideal for personal use and home server environments.
3. What Role Does Docker Play in Continuous Integration and Continuous Delivery (CI/CD)?
Docker plays a pivotal role in CI/CD by creating an isolated and consistent environment for building, testing, and deploying applications.
With Docker, developers can create lightweight containers to test their code in the same environment in which it will run in production, thus reducing “works on my machine” issues.
4. How is Docker Different from Traditional Virtual Machines?
While virtual machines emulate an entire operating system along with the hardware, Docker containers share the host system’s kernel, making them much more lightweight and efficient. A single server can run many more Docker containers than virtual machines.
5. What is the Purpose of Docker Images and How Are They Used?
Docker images are read-only templates containing an application’s code along with the dependencies it needs to run. They are used to create Docker containers, and developers can pull pre-built images from Docker Hub or create their own images.
Docker images provide a consistent environment for applications to run, making them essential tools in a Docker project.
6. Why Should I Use Docker Compose in My Docker Project?
Docker Compose allows developers to define and manage multi-container Docker applications. It simplifies the process of managing complex applications composed of multiple interlinked containers. You can spin up your entire application with a single command, making Docker Compose a powerful tool in any Docker project.
7. How Does Docker Contribute to Efficient Software Development?
Docker contributes to efficient software development in many ways. Its ability to create isolated environments for building, testing, and deploying applications streamlines the development process.
Furthermore, using Docker containers helps reduce the discrepancies between development, staging, and production environments, ensuring a smoother deployment process.
8. What is the Docker Mon Tool Used for in Docker Projects?
Docker Mon is a tool that provides real-time metrics and analytics about your Docker containers. It is especially useful in a production environment where it’s essential to identify and address issues promptly.
Docker Mon can help you track performance, resource usage, and more, thus playing a key role in managing Docker containers effectively.
9. Are Third-Party Images on Docker Hub Safe to Use?
While many third-party images on Docker Hub are safe to use, it’s always a good practice to check the source and contents of the images before using them.
Always prefer images from trusted and verified sources, and inspect the Dockerfile for any suspicious commands or components.
10. How to Manage the Data in Docker Containers?
Data in Docker containers can be managed using Docker volumes. A Docker volume is a unit of storage that Docker manages outside the container’s Union File System.
Docker volumes store data from the container’s lifecycle, allowing data to persist even when a container is deleted. Use the docker volume command to manage volumes associated with Docker containers.
Docker resonates with developers and organizations worldwide as a critical tool for modern applications. Its extensive capabilities in creating, managing, and deploying containerized applications have made it an industry mainstay. Learning the best Docker containers commands for interacting with the technology is essential to using Docker effectively.
Docker is also a great tool for learning in the home lab, as it allows you to easily spin up technologies and solutions for testing or running home lab services. Running containers in the home lab also provides a great way to learn the technology and Docker commands.