The Registry can be either a user’s local repository or a public repository like a Docker Hub allowing multiple users to collaborate in building an application. Even with multiple teams within the same organization can exchange or share containers by uploading them to the Docker Hub, which is a cloud repository similar to GitHub. Docker took off with software developers because it found a novel way to package the tools required to build and launch a container in a more streamlined and simplified way than was previously possible. Broken down into its component parts, Docker comprises Dockerfile, container images, the Docker run utility, Docker Hub, Docker Engine, Docker Compose, and Docker Desktop. Creating a Docker image with all of its dependencies solves the “but it worked for me on my development
machine” problem. The key idea is that a Docker image is created automatically by a build pipeline from
a source-code repository like Git and initially tested in a development environment.

That said, some mainstream apps like eBay, PayPal, and Shopify still use Docker Swarm, so it’s still a good fit for certain use cases in the world of cloud-native application development. Its user-friendly interface makes it relatively straightforward to containerize apps and test them out on a single machine (or small group of machines), as a single developer might want to do. But in terms of scalability, it lacks the advanced networking features of Kubernetes’ orchestration environment. It’s especially good at managing resource-intensive applications by spreading workloads across clusters of devices. This makes it an ideal pick for microservices-based applications that market their products as having ’99.9% uptime’ or some other promise to that effect. Now that you know how to use Docker to run and deploy a containerized application, it is time to look at an example of a fully automated containerized application in a future article.

Understanding Docker Containers

This way Docker can check if a layer has changed when building an image and decide whether to rebuild it, saving a lot of time. This hash-diffed layer architecture is possible because of the AuFS file system. This is a layered FS that allows files and directories to be stacked as layers one upon another. It was, at the time, the first and most complete implementation of a container management system.

Whenever a developer makes changes to the image, a new top layer is created, and this top layer replaces the previous top layer as the current version of the image. Previous layers are saved for rollbacks or to be re-used in other projects. With Docker, you don’t get the same UNIX-like functionality that you get with traditional Linux containers. This includes being able to use processes like cron or syslog within the container, alongside your app. There are also limitations on things like cleaning up grandchild processes after you terminate child processes—something traditional Linux containers inherently handle.

Docker vs. Linux containers: Is there a difference?

To make it easier and more efficient for developers to create
containerized applications, cloud providers offer Container Cloud
Services or Containers as a Service (CaaS). Container Cloud Services
help developers and operations teams streamline and manage the lifecycle
of containers in an automated fashion. What Is Docker These orchestration services,
typically built using Kubernetes, make it easier for DevOps teams to
manage and operate containerized applications at scale. Oracle Container
Engine for Kubernetes and Azure Kubernetes Service are two examples of
popular container orchestration managed cloud services.

These clusters of containers do then need to be orchestrated, which is where Kubernetes typically comes in. By simplifying this process, Docker quickly became close to a de facto industry standard for containers. Docker let developers deploy, replicate, move, and back up a workload in one streamlined way, using a set of reusable images to make https://deveducation.com/ workloads more portable and flexible than previous methods allowed. When starting a container, Docker will by default automatically pull the corresponding image from the
public Docker Hub if it is not available locally. Moreover, you can also create your own images and push
them to Docker Hub into either a public or private repository.