Everything You Need to Know About Docker


If you are a developer or just someone who is immersed in the IT world, you have probably heard of Docker.

Docker is a tool that helps create, deploy, and run applications by an easier use of containers. This tool is really powerful since it allows developers to package up an application with all of the parts it needs, such as libraries, and other dependencies, and deploy it as a single package.

Due to that, a developer can rest assured that apps will run on any other Linux machine no matter what customized settings that machine might have.

So, take a look below and learn more about Docker.

Remember, it doesn’t matter if you are creating an app for finances, travel, and so on, or you are creating an app to manage a WordPress site or something similar, you will definitely need powerful tools at your disposal.

Docker, certainly, is one of those tools.

Who uses Docker?

Docker is a tool designed to benefit both developers and system administrators. This makes it quite an important part of many DevOps (developers and operations) toolchains.

Thanks to Docker, developers can focus on writing code without worrying about the system that it will ultimately be running on.

This tool also allows them to get an edge when it comes to time spent by using one of the thousands of programs already designed to run in a Docker container as part of their app. This is, among other things, one of the reasons why Docker container hosting is a hot topic too.

When it comes to operations staff, this tool provides flexibility and potentially reduces the number of systems needed since it has a small footprint and lower overhead.

Benefits of Docker

The way containers work resembles, to an extent, the way VMs work. However, let’s look at it in a more specific way.

Containers isolate a single application and its dependencies — all of the external software libraries the app requires to run — both from the underlying operating system and from other containers.

All of the containerized apps share a single, common operating system (Linux or Windows), but they are compartmentalized from one another and from the system at large.

Now, take a look at some major benefits of Docker and containers.

– Docker allows for faster software delivery cycles
Enterprise software has to respond quickly to changing conditions. In other words, both easy scalings to meet demand and easy updating to add new features as the business requires are necessary.

Docker containers make it easy to put new versions of software, with new business features, into production quickly — and to quickly go back to a previous version if needed. They also make it easier to implement strategies like blue/green deployments.

– Docker enables great use of system resources
Containerized apps use considerably less memory than virtual machines. They start up and halt faster, and they can be packed far more densely on the host hardware. As a result, all of this helps spend less on IT.

The cost savings will vary depending on what apps are in play and how resource-intensive they may be, but containers invariably work out as more efficient than VMs.

It’s also possible to save on the costs of software licenses since you need many fewer operating system instances to run the same workloads.

– Docker allows application portability
It is quite important where you run an enterprise application. It matters if you are running it behind the firewall because you want to keep everything safe and secure in your near vicinity.

But, this can also be kept out in a public cloud for easy public access and high elasticity of resources.

Docker containers encapsulate everything an application needs to run (and only those things), they allow applications to be shuttled easily between environments.

Any host with the Docker runtime installed — a developer’s laptop or a public cloud instance — can run a Docker container.

– Docker for microservices
Thanks to the fact that Docker containers are light, portable, and self-contained, it is easier to build software along forward-thinking lines, so that you’re not trying to solve tomorrow’s problems with yesterday’s development methods.

One of the software patterns containers make easier is microservices, where applications are constituted from many loosely coupled components.

By decomposing traditional, monolithic applications into separate services, microservices enable the different parts of a line-of-business app to be scaled, modified, and serviced separately — by separate teams and on separate timelines if that suits the needs of the business.

Containers aren’t required to implement microservices, but they are well-suited to the microservices approach and to agile development processes generally.

Shortcomings of Docker (what Docker can’t do)

Now that you are aware of the more prominent benefits of Docker containers, let’s see what these containers can’t do.

– Docker can’t solve security problems
The software in a container can be safer by default than software run on bare metal, but that’s a bit absurd. It is obvious that a house with all its doors locked is a lot safer than a house where all the doors are open wide, right?

This doesn’t say anything about the condition of the neighborhood or the visible presence of valuable items thieves would look for, the routines of the people living there, and so on.

Containers can add a layer of security to an app, but only as part of a general program of securing an app in context. Bear that in mind!

– Docker can’t substitute virtual machines
There is one huge misbelief that containers actually make virtual machines obsolete.

Many apps that used to run in a VM can be moved into a container, but that doesn’t mean the entirety of them can or should be moved.

For example, if you’re in an industry with heavy regulatory requirements, you might not be able to swap containers for VMs, because VMs provide more isolation than containers.

– Docker can’t miraculously transform apps into microservices
If you containerize an existing app, that can reduce its resource consumption and make it easier to deploy. But it doesn’t necessarily change the design of the app, or how it interacts with other apps.

Those benefits only come as a result of a developer’s hard work, not just a mandate to move everything into containers. Put an old-school monolithic or SOA-style app in a container, and you will end up with an old app in a container.

This doesn’t make it more useful for your work. It actually makes it less useful.

Final thoughts

It is safe to say that enterprise development work is known for being hidebound and slow to react when it comes to changes.

Developers working on enterprise-grade software have to deal with these constraints all the time. There are limits imposed on them by IT and there are demands coming from their companies.

Docker and containers provide developers with more of the much-needed freedom. But at the same time, they also provide developers with new ways to build business apps that respond quickly to business conditions that are bound to change.