Docker Tutorial for Beginners

What exactly is Docker?

Docker is a software framework developed as part of the Moby project. It is used for constructing, running, and managing containers on servers and in the cloud. The word "docker" can mean either the tools (commands and a daemon) or the file format for Dockerfiles.

In the past, if you wanted to run a web application, you had to buy a server, install Linux, set up a LAMP stack, and then run the application. If your app became popular, you implemented load-balancing best practices by setting up a second server to prevent the application from crashing due to excessive traffic.

However, times have changed, and rather than focusing on individual servers, the Internet is now built on arrays of interdependent and redundant servers in a system that is commonly referred to as "the cloud." Because of technological advancements such as the Linux kernel namespaces and cgroups, the idea of a server could be liberated from the limitations imposed by hardware and transformed into the functional equivalent of a piece of software. These software-based servers, known as containers, are a hybrid combination of the Linux operating system they're running on and a hyper-localized runtime environment. Containers are also virtual machines (the contents of the container).

What is containers?

The technology behind containers can be divided into three distinct categories, namely:

• A builder: is a tool or series of tools that are used to construct a container. Examples of builders include the distro builder for LXC and the Dockerfile for Docker.
• An engine: is a program that runs a container. This is about Docker's docker command and dockerd daemon. This can be used to talk about the containerd daemon and other commands (such as podman.)
• The term "orchestration" refers to the technology that is utilized to manage multiple containers, such as Kubernetes and OKD.

Containers often come with both an application and its configuration. This means that a system administrator can spend less time getting an application running in a container than installing it from a traditional source. Dockerhub and Quay.io are both places where images that container engines can use can be stored.

The ability of containers to "die" in a dignified manner and respawn when load balancing necessitates it is perhaps the most appealing feature of containers. Containers are "cheap" to start and designed to appear and disappear seamlessly. This is true regardless of whether a crash brings about the demise of a container or because it is simply no longer required because server traffic is low. It is to be anticipated that the monitoring and management of containers will not be performed in real time by a human being. This is because containers are designed to be ephemeral and to spawn new instances as often as necessary.

Docker alternatives

There has been a significant shift in high-availability computing made possible by alternatives to the Docker Linux container platform. You can run your services or entire operating system inside containers with various available toolkits. The Open Container Initiative (OCI) is a group that sets industry standards and promotes innovation while avoiding the risk of being locked into one vendor. You can choose from Docker, CRI-O, Podman, LXC, and other container toolchains thanks to the Open Container Initiative (OCI).

Utilities for containers

Containers are made to grow quickly, whether you're running many different services or many copies of a few services. If you choose to run services within containers, you will likely require software intended to host and manage those containers. This is broadly known as container orchestration. Docker and other container engines, such as Podman and CRI-O, are useful utilities for the definitions and images of containers. However, the purpose of these engines is to create and run containers; it is not their job to assist you in organizing and managing containers. Container orchestration is provided by projects such as Kubernetes and OKD for Docker, Podman, CRI-O, and others.

When putting any of these into production, consider investing in support through a downstream project such as OpenShift (which is based on OKD.)

What you absolutely must be aware of concerning the Docker Community Edition

TDocker Community Edition, or docker-ce, is a product that combines the open-source components of Docker. These include the Docker engine and a set of Terminal commands that administrators can use to assist them in managing all of the Docker containers they are utilizing. Installing this toolchain is as simple as searching for "docker" in your preferred distribution package manager.

Why should you use Docker?

You can choose the most appropriate technology for the job when you work with open-source software, which is one of its many attractive features. The Docker engine can be helpful for developers who work alone and need a clean, light environment for testing but don't need to do a lot of complicated orchestration. Docker Community Edition, also known as docker-ce, is an excellent option for getting started with containers if Docker is already installed on your computer and everyone around you is already familiar with the Docker toolchain.

Dockerhub and Quay.io are repositories offering images for your container engine of choice. Podman is an excellent alternative to consider using if Docker Community Edition is either unavailable or not supported. The effort to ensure open standards prevail is ongoing, so the essential long-term strategy for your container solution should be to stick with projects that respect and foster open source and open standards. After committing your tools to a product that does not permit migration, proprietary extras may at first appear to be appealing; however, as is typically the case, you will lose the flexibility of choice once you have made that commitment. Containers can be liberating as long as they're liberated.