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Everything you need to know about Docker

By John Cleary
23/04/2020

Everything you need to know about Docker

In this industry, there are a myriad of tools available to get the job done. Everyone has their own preferences, the one thing that makes their lives easier, but one that has become an essential part of many people’s daily process – ours included – is Docker.

Docker was designed to make running, creating, and deploying applications easier. The main way it does so is through containerisation; packaging up software and making it easier to run on different platforms and servers.

While we think Docker is great, you don’t have to take our word for it. More than 3.5 million applications have been placed in containers using the technology and over 37 billion containerised applications have been downloaded. Let’s look at why.

What is Docker?

Docker functions similarly to a virtual machine, except it doesn’t create a distinct operating system all of its own. Instead, it uses whatever system is in the background and runs its own applications off that. 

Containers allow developers to wrap up their applications with all the packages, libraries, and dependencies they need. It makes it possible to package and deploy them as separate, isolated entities. This means applications are more portable and it becomes easier to distribute them in efficient, standardised ways.

These containers use shared operating systems and therefore offer better efficiency, are more streamlined, and self-sufficient. They are more flexible, allowing an application to run on any machine that is compatible with the Docker system. And as its awareness and popularity has massively increased over time, this means you can run your applications hassle-free from virtually anywhere. 

Without Docker, you would have to install all of an application’s dependencies separately. This causes issues if a machine has niche, customised settings or doesn’t support certain packages. It gives you the freedom and flexibility to use the same applications on many different servers.

Why we use Docker

At Createk, we find Docker provides us with greater autonomy. Instead of needing a plethora of specific packages or software installations on our machines, we simply install it and can effortlessly run any of the applications we’re currently working on. There’s no need to adapt code, change settings, or install software in line with new projects.

Some of our developers don’t even need to have a specific language or framework version installed locally on their machine. This is great for scenarios like onboarding a new member of the development team or if one of our developers needs to use a different machine to normal. Docker makes our jobs easier and operations more efficient as it allows us to spend less time debugging environment-specific issues or setting up new environments altogether.

We also use it for our application testing. We tend to use CircleCI for continuous integration and Docker fits into this nicely, meaning our test suite can use our application’s image to run its tests against.

Finally, it is great for running and developing our sites under custom URL endpoints. We can tell the system to run our application on the URL ‘my-awesome-new-web-app.localhost’ and this will become available for us to access. If we have an SSL certificate set up for this domain, we can also tell Docker to serve our application via HTTPS.

Benefits of Docker in production 

Docker can also be a valuable tool for production. Again, its consistency is a big plus. If it runs correctly in development, we can be fairly certain it’ll run correctly in production. This minimises a lot of issues relating to subtle differences between development and production environments.

Using Docker in production also provides cost benefits, making it easier to ensure you’re only paying for what you use. Configuring your billing plan to the resources you actually use means you no longer have to pay for a large number of virtual servers that may only ever get used to their full extent when site traffic is high. 

Dockerised environments allow for infrastructure to scale in direct response to fluctuations in requests. This is handled by something called a container orchestration service. There are various services available such as Kupernetes, AWS ECS, and Azure Orchestration. 

Containers vs serverless

Serverless computing is an architectural approach which means code is only executed on demand. All a developer needs to do is upload the code and specify when it should execute.

Serverless code tends to run within specific services like AWS Lambda or Azure Functions, as opposed to within a Linux server or similar. This means you’ll be stuck using a cloud-based solution most of the time. While this isn’t the end of the world, it isn’t always an option for businesses that require an on-site data centre or hosted environment. On the other hand, containers can run on any modern Linux server.

Serverless solutions also only tend to come in specific languages. For example, at the time of writing, AWS Lambda supports Java, Go, PowerShell, Node.js, C#, Python, and Ruby. However, a containerised or traditional vertical server set-up can run any language or framework that the host server can support.

A winning combination

Containers and serverless are two very different tools. And while there are certainly some similarities, both tend to solve different problems. For example, a container can run for however long you need it to, whereas serverless code is designed to execute and shut down after a short period. 

Containerisation is great for running stateful applications that require backing storage, as opposed to serverless technologies which are great at running one-off pieces of code. Many companies tend to adopt both pieces of tech to complement each other in delivering an application. Combined, they make development a much easier, efficient, and streamlined process.

To summarise, Docker makes our job a lot easier. Containerisation makes creating, running, and transporting applications a simple and straightforward task. And the shared operating systems offer us flexibility throughout both our development process and later on in production. Containers also help to fill some of the gaps we find in serverless solutions, offering more choice when it comes to languages and frameworks.

At Createk, we bring together our vast knowledge and years of experience with product development, management, and maintenance to help our clients be their best. We provide state-of-the-art, modern applications that help our clients to become more efficient, professional, and competitive. To find out more, call us today on 0330 995 0685.

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