Docker and Kubernetes: How You Can Benefit From Using Both
Software creation is not just about writing code. The real challenge is dealing with multiple programming languages on different platforms and managing various interfaces and tools. Modern developers successfully cope with this task by using containerization technology. It allows them to isolate applications in separate spaces (containers) independent of the external environment and other apps.
Kubernetes and Docker are the two leading tools used in containerization technology. Many try to compare them; however, this approach is not correct because they have different areas of responsibility. While Kubernetes is a container orchestration system, Docker is a virtual container management tool.
A smart combination of both helps achieve fast results during software deployment. However, given the recent Kubernetes announcement to stop supporting Docker as a container runtime, you need to know how to properly combine both technologies to maintain containerized apps. In this article, we want to emphasize the relevance of containerization with Docker and Kubernetes and share how you can use both in the new realities of upcoming changes.
Five popular SaaS that utilize Kubernetes
SaaS (Software as a Service) built with Kubernetes are ready for use solutions with prebuilt deployment templates that enable easy portability and scaling up. Kubernetes app advantages lie in super adaptability. They can be run in local environments, the cloud, or on Kubernetes clusters hosted elsewhere. Below, we will name the most prominent SaaS examples designed with containers and Kubernetes in mind.
GitLab, a web application and code repository management system for Git used by 30 million users from all around the world (including IBM and NVIDIA employees). GitLab offers a solution for code storage and collaborative development of large-scale software projects. It is an innovative all-in-one system for all stages of the DevOps lifecycle.
CloudBees, a software delivery management (SDM) system for growing organizations. CloudBees provides continuous integration (CI) and continuous delivery (CD) tools for effective collaboration within the enterprise. It is mainly made for software engineers and product teams.
Neo4j, a high-performance NoSQL (non-structured query language) database based on the principle of graphs. It does not have tables with strictly specified fields but operates based on a flexible structure of nodes and connections between them.
Seldon, a multifunctional analytic system to search and analyze purchases. It provides comprehensive information about all purchases in Eastern Europe and beyond. The users can track state trading, commercial procurement, property auctions, and more.
Aerospike, a distributed NoSQL database and a key-value store. It provides estimated data access time and meets the needs of today’s web-scale apps in real-time data processing.
The pros and cons of using Docker
Docker toolkit helps solve problems with updating components, app portability, and much more. However, you should look for Docker alternatives in some cases because the technology may be unsuitable for specific tasks and may not meet particular user expectations. Below, we list the key Docker benefits and explain when it is better not to use Docker.
When Docker is a good choice
Application abstraction. The container connects to the host through a specific interface so that the containerized application does not depend on the external environment, providing it is targeted at the specific OS — Mac OS, Linux, Windows, Virtual Machine, Cloud, etc.
Ready-to-use environment. In a container, all components and dependencies are linked directly to the app, so there is no need to adjust additional settings on the host to run the application.
Easy migration. When migrating to another instance, you do not need to rewrite permissions, configs and set up the environment from scratch. Instead, you can run the application from the Docker image on a new instance without any reconfiguration.
Space savings. Multiple Docker containers can easily use one layer without duplication. This approach is very economical as it minimizes the use of disk space.
When Docker is not the best option
When you need to increase the app speed. Docker will use as many system resources as the host kernel scheduler will allow. That is why you should set limits for each container’s memory usage, CPU, and I/O block.
When you create a desktop app with a graphical user interface (GUI). Windows uses Nano Server or Core Server as the operating system for containers — this prevents users from running a GUI or Docker RDP (remote desktop protocol) server in a Docker container.
When you need to use a different operating system or kernel. There is an extensive database of Docker container images — Docker Hub (you can check the Docker Hub pricing here). But if a particular image was created on a specific architecture, it can only be run on exactly the same architecture. For example, there is no way to run a container built for amd64 on ARM.
Kubernetes special aspects: pros and cons to consider
Kubernetes simplifies IT infrastructure management and makes it more flexible. It allows apps to be moved between different environments and makes it easier to manage a large number of containers.
Imagine a large warehouse where all products are packed in boxes. To automatically track, schedule, and organize them, you need an orchestration solution. This is what Kubernetes was created for.
Below, we’ll review Kubernetes in more detail by highlighting its strong and weak points.
Autoscaling. Kubernetes allows you to automatically scale up and down workloads based on resource usage. Its autoscaling has two dimensions: cluster autoscaling and horizontal pod autoscaling (HPA).
- The cluster autoscaler is responsible for scaling nodes
- The HPA is responsible for scaling the number of pods in a deployment or replica set
Orchestration. Kubernetes helps create information systems from many containers, each responsible for only one specific task. The communication between containers is carried out through network ports and shared directories. Each container can be replaced with another container. Thanks to this, you can quickly switch to a different database version.
Self-management. Kubernetes restarts failed containers, replaces and shuts down damaged containers, and does not show them to clients until they are ready to use. Thus, you can always be sure of the proper system functioning as a whole and each container in particular.
Sensitive information management. Kubernetes can store and manage sensitive information such as passwords, OAuth tokens, and SSH keys. You can deploy and update sensitive information and app configuration without changing container images or revealing sensitive data in the stack configuration.
With all the pros of Kubernetes, it has some cons you should be aware of.
Complex installation. Kubernetes requires significant technical effort from the DevOps team. It takes time to be properly installed and configured.
Expensive operation. The superior technical capabilities of Kubernetes are not inexpensive and you should expect to pay accordingly for DevOps services to build and maintain the Kubernetes tools.
Lack of high-quality specialists. It is not easy to find DevOps experts who are fluent in Kubernetes technology and can effectively use it in practice.
Docker + Kubernetes = still the perfect container solution
Until recently, Docker has complemented Kubernetes perfectly. Docker has been a primary tool for many organizations to create containers, and Kubernetes has been a perfect way to manage them. The upcoming changes made some adjustments to the well-coordinated work of the Docker + Kubernetes pair but did not break their union altogether.
Let’s start with the fact that the trouble is faced only by those who manage Kubernetes clusters on their own. Such companies need to re-configure clusters to use compatible container runtime environments different from Docker. In particular, they need to set environments that use the Container Runtime Interface (CRI) — containerd and CRI-О.
This step is necessary because Kubernetes plans to remove the Dockerism layer used to access containers. As a result, kubelet (the process managing your modules at the k8s node level) will interact with CRI directly. Considering Docker API is not compatible with Kubernetes CRI, the Docker + Kubernetes combination will not work in this case.
Despite this, Docker images will still work in future Kubernetes versions. This is because images created by Docker are not Docker-specific. Instead, they are the OCI (Open Container Initiative) images, which both containerd and CRI-О can fetch and run. Besides, no changes will be required when using managed services like GKE, EKS, or AKS because they utilize containerd by default.
In such a manner, you can still use a Docker container to pack an app and Kubernetes to quickly scale and deploy it. The combination works exceptionally well in enterprise-level apps where multiple containers are deployed. Managing them manually is a challenging task, so the Kubernetes management system is ideal for the rapid deployment of large-scale projects and the launching of an app.
Today, most projects run in the cloud, and many cloud apps are made using Docker. Among other reasons, developers choose this solution because of the handy Docker toolkit, which is perfect for deploying containers on the leading cloud platforms — AWS and Microsoft Azure. The combination of cloud technologies + containerization makes the development process even more flexible, allows using the latest innovations on-demand, and helps to quickly fill the product with new features. Additionally, if you originally developed a containerized application on-premises, you can easily migrate it to the cloud due to the vast capabilities of Docker in-cloud computing. These features allow you to run an app on any platform without changing settings inside the container, although rebuilding for a different architecture may be required.
Where to hire Docker and Kubernetes experts?
To successfully use Kubernetes and Docker in software development, you need a reliable DevOps team. However, according to the DevOps Trends Survey, 37% of companies experience difficulties in implementing effective DevOps due to the poor skills of their employees. For this reason, many clients from the USA and Western Europe expand their search geography and outsource DevOps services abroad. If you are facing the same problem and want to find DevOps engineers with proven expertise, consider hiring Ukrainian experts. International IT ratings recognize the high quality of Ukrainian software products, and the cost of hiring Ukrainian developers is much lower than for those from the USA and Western Europe.