Docker: The Role of Containers in Your Microservice Architecture

Docker was able to revolutionize software development. This approach allows you to put the resources you need for development into containers (or code wrappers). Docker architecture (container technology) is the cornerstone of mobile scalable development.

Developers are actively using Docker to create microservices that allow them to split all tasks into small standalone applications. They all interact with each other to ensure smooth operation. In this article, we will make it clear how Docker works and how you can use it in your development even more effectively.

What Are Containers?

A container is a unit of software that packages code and all of its dependencies so that an application can easily travel between computing environments. The Docker component, - image, - provides everything you need to run your application. Images become containers the moment they run in the Docker Engine.

Containerization is available not only on Linux, but also on Windows, which guarantees correct and consistent application instance performance under all conditions.

Docker containers have the following characteristics and benefits:

• Due to the fact that it was Docker who created the standard for resources containers, they can be ported anywhere;
• Since Docker containers share the kernel of the machine's OS, there is no need to incur licensing and server costs, and the containers themselves are lightweight;
• Containers are safer due to more efficient and reliable isolation capabilities.

Thus, containers are an alternative to virtual machines. Thrifty abstraction and providing exactly the resources needed to get the application up and running improves the responsiveness of the application.

What Are Microservices?

Microservices represent one of the modern approaches to application development. Here, each app is a set of services, each of which has its own processes and which exchange data through the API. Despite the fact that microservices appeared before containers, they have gained particular popularity in recent years.

Unlike the monolithic approach that predates microservices, microservices allow you to break your application down into core functions during development. Thus, each function can be started and processed (or generate errors), without affecting others. Microservices increase the resiliency of the application and the possibility of its scalability in the future.

Read also: Everything You Need to Know About Web Application Architecture

Why Use Microservices Architecture in Your Project?

The main benefits of microservices is the lack of interdependencies between the elements of the system. That is, even if a part of the application crashes, it does not affect its operation as a whole.

In addition, microservices offer business benefits such as:

1. High flexibility and easy scaling

Any bug fixing, improvement of a product component or its parts is faster and easier. Everything can be done independently, up to scaling.

2. Convenience of testing and speed of error elimination

Testing and maintaining modules is faster, and component independence plays a key role here. In a monolith, you have to test the entire application at once, and any error leads to the failure of the entire application.

3. Connection speed

The adaptation process is faster, since the specialists responsible for the individual modules can immediately assess their work and launch.

4. Flexibility in the choice of technologies

Each developer can use different technologies, according to preference, for each module, provided that it does not contradict the business logic of the project. At the same time, there is no need to rewrite the entire application microservices or adapt it to the technology stack.

5. Ease of deployment

In addition to simple deployment independent of other developers, using CI / CD and CI tools (for example, Jenkins, Hudson), you can completely automate the process. You also get easy and efficient integration.

Microservices are suitable for almost all applications, making the development process as optimized as possible. Especially when it comes to large complex applications. Exceptions for microservices are Single Page Applications, MVP and Proof-of-Concept. You can also use monoliths for small audience applications, but it's important to note that even they can be refined and scaled with microservices.

The Docker Definition

Docker container technology is a platform for acting with containers on a common OS with an extended Docker ecosystem of interconnected tools. Docker is open source, and the technology itself was presented in 2013.

Docker works like this:

Docker deals with packaging, provisioning and launching containers that can also be cloned. Each container contains an application service or function (including its libraries, configuration files, dependencies, and so on). When creating a container, a Docker document is created, which contains all its parameters and requirements, you can use both custom solutions and ready-made solutions. Each container uses the services of one underlying OS (Windows / Linux / MacOS). There are also Docker versions for Amazon Web Services (AWS) and Microsoft Azure.

One of the key differences and advantages of Docker over a virtual machine is the use of resource isolation in the OS kernel, in order to run multiple containers within one OS. Whereas the virtual machine hides the entire OS and code on top of the layer of physical hardware resources.

The Pros & Cons of Docker in Microservices Architecture

As mentioned above, microservices are autonomous units in development, united by a common goal. There is a disadvantage in the same advantage: the complexity of managing all components, especially with differences in the technological stack of microservices. And this is where Docker comes in. It allows each microservice to be encapsulated and managed without any complexity.

As an efficient containerization technology, Docker helps developers solve application deployment challenges and dramatically reduce the time spent running an application. Docker helps maintain consistency across all microservice containers and helps with memory and access management.

But due to the large number of Docker features, let's consider Docker advantages and disadvantages in more detail.

Pros

Work on Mac and Windows

Thanks to its abstraction, Docker works great on Mac and Windows. This makes things a lot easier for developers who don't run Linux.

Consistency for the whole team

Thanks to this Docker property, you can easily run processes and scripts with your entire team without fear of technical misunderstandings. With the same settings, you can always work smoothly.

Ease of debugging environments

Docker will allow you to isolate and troubleshoot your team without having to figure out the stable environment settings for each team member individually. This saves developers time and resources.

Lots of automation options

Docker infrastructure allows you to port your environment to your chosen CI system, automating most development processes. For example, you can set up testing of applications or their components.

Speeding up the preparation process

Docker allows out-of-the-box solutions from containers, such as ssh public keysets, or forcing users to use private keys in an identity service.

The Docker community is huge

Docker Hub offers an incredible number of pre-built images that you can use in your development. These images will help you create containers for deploying microservices

according to proven schemes. You can also always read the documentation and find questions for almost any question that arises while working with Docker.

Cons

The microservices Docker situation has some disadvantages as well.

Small gaps in the documentation

Since Docker is evolving very quickly, not all of its new features and functions are documented. And if you are using the latest innovations, you may have questions that will be difficult to find answers to.

Performance issues in foreign environments

While Docker performs significantly better on Mac and Windows today, in fact it still requires a Linux kernel to perform its operations. For everything else, you need an abstract virtual machine that you won't interact with directly. This loads the process a little and makes it harder.

Docker is not easy

If your team does not have a ready-made specialist who is familiar with Docker, you will need to invest time and resources to learn this technology.

Additional Tools for Microservices

Since the key idea behind a microservice is to create production services that can be tested and deployed independently of each other, there is a specific set of tools required to make them work. Microservices can use their own databases and various programming languages, but they will still communicate seamlessly.

TopDevs specialists identify the following necessary tools for working with microservices:

• Container, Orchestration systems, IaC
• Cloud and serverless infrastructures
• API gateways
• Enterprise Service Bus
• Service discovery.

These are the most relevant technologies for microservices, which can also be used in some other cases.

More about technologies and development you can find on Techreviewer.

Summary

Modern approaches to application development rarely do without the use of architecture microservices and Docker benefits. The main reasons for preferring this tandem are to play for the future and work together to achieve a result. This is especially important for DevOps specialists who are responsible for debugging development processes.

The involvement of the entire team in development, without interfering with each other's processes (which happens, for example, in monolithic applications when working on scaling or adding additional functions), and the ease of managing all containers with microservices at the same time, turned Docker into an indisputable favorite in containerization issues, and namely Docker today sets the standard for work in its area.