Container approach for your digital transformation

Introduction

The adoption of new development paradigms as well as architectures that are more robust and easier to maintain and evolve must be taken with care before starting a project, to assess the impact on your development teams, your budget, or your infrastructure.

If your goal is to make the software more portable, containers are the latest variation on that theme which makes them a critical technology for cloud architects to know.

Container

Containers are the best approach to migrate existing applications into more modern environments. While this practice delivers some of the basic benefits of operating system virtualization, it does not offer the full benefits of modular, container-based application architecture.

A containerization is an approach to software development in which an application or service, its dependencies, and its configuration are packaged together as a container image.?

Container technology supports streamlined build, test, and deployment from the same container images.

Containers isolate applications from each other on a shared OS, they, therefore, have a much smaller footprint than virtual machine (VM) images.

Containers Deployment

If we come back to our 5R strategy for cloud migration dedicated to containers, we can see how we can deploy if we want to rehost or refactor, use the microservice approach if we decide to rearchitect and for a new application we have to build patterns to adopt a cloud-native strategy in the future.

Container vs VM

Containers and virtual machines have the same roles: the goal is to isolate an application and its dependencies into a self-contained unit that can run anywhere. Taking into consideration that containers and virtual machines eliminate the need to have physical hardware in order to use computing resources efficiently, both in terms of energy consumption and profitability.

So what's the difference?

The main difference between containers and VMs or virtual machines is in their architectural approach. A virtual machine is basically an emulation of a real computer that runs programs like a real computer. Virtual machines run on a physical machine using a hypervisor.

Virtual machines wrap the virtual hardware which is the kernel, i.e. our operating system, and a user-space for each new virtual machine. The applications and the operating system will be in each VM unlike a virtual machine that provides hardware virtualization, a container is virtualized at the operating system level abstracting from userspace. The container only embeds the user space and not the kernel or virtual hardware like a virtual machine does. Each container has its own isolated userspace to allow multiple containers to run on a single host machine. So all the OS-level architecture is shared between containers. The only parts that are created from scratch are libraries and binaries. That's what makes containers so light. Despite the advantages of using a virtual machine, such as running many applications securely, in different environments on the same physical server they consume a good portion of server resources just to operate. They must simulate a physical server with all its components. Additionally, each virtual machine needs its own operating system; which can be a source of performance loss, but also software vulnerabilities. And here come containers, which have improved most of the services offered by virtual machines and are more suited to the modern software architecture of micro-services. But they do not replace them. Very often, we will find them living side by side.

Each container uses the host server's operating system; while each virtual machine hosts its own operating system.

Docker

Docker is a tool that facilitates the creation, deployment, and execution of applications using a containerization approach. These containers are lightweight and take less time to boot than traditional servers. These containers also increase performance and reduce costs, while providing appropriate management of resources. Another advantage of Docker is that it is no longer necessary to pre-allocate RAM to each container.

Overview Docker Container and Image

Introduction to Docker Images

Docker is a tool that makes it easier to create, deploy, and run applications by using a containerization approach. These containers are lightweight and take less time to start than traditional servers. These containers also increase performance and lower cost, while offering proper resource management. Another benefit to using Docker is that you no longer need to pre-allocate RAM to each container.

Docker Container and Docker Image

A Docker container is a virtualized runtime environment used in application development. As mentioned before in the definition of Docker, with Docker, we are able to create, run and deploy applications?that are isolated from the underlying hardware.?A Docker container can use just one machine, share its kernel and virtualize the OS to run more isolated processes. So, Docker containers are?lightweight.

A? Docker image?is like a snapshot in other types of VM environments. It is a record of a Docker container at a specific point in time. Docker images are also immutable. While they can’t be changed, they can be duplicated, shared, or deleted. The feature is useful for testing new software or configurations because whatever happens, the image remains unchanged.

Containers require the existing runnable images to exist. They are dependent on images because they are used to construct runtime environments and are needed to run an application.

Containerized applications can get complicated, however. When in production, many might require hundreds to thousands of separate containers in production. This is where container runtime environments such as Docker benefit from the use of other tools to orchestrate or manage all the containers in operation.

One of the most popular tools for this purpose is Kubernetes, a container orchestrator that recognizes multiple container runtime environments, including Docker.