Containers have become one of the most popular concepts used in ITand software industry in the last five years.Since the introduction of Docker,containers have evolved to a larger ecosystemthat include many tools and technologies,including Docker and Kubernetes.Before we go into too much detail,let's look at why containers have becomeso popular and how they're used.

First off, containers aren't a new topic.They've existed for a number of years and havetaken many forms before the creation of Docker.As you can see here, in generala container is defined as a collectionof software processes unified by onenamespace with access to an operatingsystem kernel that it shares with othercontainers and little or no access between them.

Docker modifies this definition by sayingthat a container is a runtime instanceof Docker images that contain three things,a Docker image, an execution environment,and a standard set of instructions

For those coming from an object oriented world,you can use the analogy of classes and objects,where a container is an objectand the class is a Docker image.While Docker has many products and solutions,the core pieces of the ecosystemare the Docker Engine and the Docker Store,sometimes referred to as the Docker Hub.

The Docker Engine is comprised of runtimeand packaging tools and is requiredto be installed on the hosts that run Docker.The Docker Store is an online cloud servicewhere users can store and share their Docker images.

container vs virtual machine?

One question that comes up a lotis what is the difference betweena container and a virtual machine?Containers might look like a VM,but these are two distinct technologies.In a VM, each virtual machine includesmany applications, all the necessarybinaries and libraries that would existon the OS, and the entire guestoperating system to interact with them. On the other hand, a container will includethe application and all of its dependencies,but will share the kernel with the other containers.It is not tied to any specific infrastructureother than having the Docker Engine installed on its host.It'll run an isolated process in theuser space on the host operating system.This allows containers to run on almostany computer, infrastructure, or cloud.From a high level, containers provide benefitsto both developers and DevOps folk alike.Developers like them because it's easyto create applications that areportable and packaged in a standard way.They also make the process of deploymentvery easy and repeatable.Testing, packaging, and integrationscan be automated in an easier way than before.Containers support newer micro services architectures,which fit better from a developer mindset.And finally, containers help alleviateplatform compatibility issues.From a DevOps standpoint, usingcontainers simplifies release management.Deployments become much more reliable,which improves the speed and frequency of releases.

The application lifecycle is consistent.They can be configured once and run multiple times,making the process more repeatable and efficient.Environments can be made more consistent.No more process differences betweenthe dev, staging, and production environments.Scaling applications also becomes a lot simpler.Containers take a few seconds to deployto a host, which makes the processof adding extra workers easier and the workloadcan grow and shrink more quickly for on-demand use cases.

One of the biggest value adds of usingcontainer technologies in an enterpriseis that developers and DevOps teamnow have a common language to collaborate.Both sets of teams can describe their needsand architectures in terms of containers usingthe same vocabulary for dev and deployment.Issues that come up in production by a DevOps teamcan be easily communicated back to a development team.The dev team can isolate and debugspecific issues to a container level,eliminating problems relating to differencesin hosts or runtime issues with applications.With all the benefits that containersbring to the table, it's no wonder thatthere's such a dramatic increase in their use.

A Forrester survey conducted in 2010indicated that organisations expect the number ofcontainerised apps will rise by 98% in 2022.The white paper is a great readand talks about some of the most prominent use casesof containers in different sized orgs.Organisations use containers to build applicationsto incorporate a micro services based architecture.Newer applications are built with a micro servicesmindset using containers underneath to realise this,and legacy applications are shipped as containersto fit the micro services mold as well.Finally, containers assist with code agilityand help you build a continuous integrationor continuous deployment pipeline.This use case really pushes an IT teamto develop, test, and deploy applicationsfaster in a more automated fashion.Hopefully by now it's clear why enterpriseshave started to adopt containers in such a big way.Now that we understand what containers are allabout!!!