A common crossroad for developers (especially when just starting) concerning containerization is the question of Kubernetes vs Docker. In this post, we will exhaust the fork down to application areas for which either side fits perfectly.
To achieve this promise, it only makes sense to define the term container in Kubernetes (K8) and Docker’s context. Call it the foundation for understanding both technologies before we dive into each of them.
- What is a Container
- What is Kubernetes
- What is Docker
- Docker vs. Kubernetes: Do You Have to Choose?
- Use Cases for Dockers and Kubernetes
What is a Container
Let’s say you wanted to deploy an application in the perfect environment for peak performance. Ordinarily, such an environment usually depends on the racks it resides, network variables, and other external infrastructure specifications. This means you’d not get peak performance 100% of the time… Unless you create a container to abstract the application from the physical location it lives.
Think of a sandbox or virtual machine with specified variables (OS type, Compute, et al.). This way, say you had to deploy another application, a container on the same hardware but with a different OS and other variables makes for an excluded environment perfect for testing and deploying the said application.
These applications, now containerized, behave as though they’re on different machines (location even). A key advantage of using containers is that we can replicate their environments wherever the application is required – doing away with compatibility mismatches that plagued the pre-container era of software development.
What is Kubernetes?
Kubernetes is a tool built by Google (2014) to orchestrate tasks associated with containers and containerization platforms. It’s an open-source project that can manage multiple containers, spreading its capabilities (see functions below) to maintain the uptime and accessibility of applications ‘contained’.
Key Kubernetes Functions
Some features of Kubernetes include the following;
- Maintaining an environment with set parameters for development, testing, and deployment
- Predictable and auto-scalable (horizontally) infrastructure
- Self-correcting (rollbacks) environment with load-balancing
- Wide surface area to deploy applications
- Application-level management tools
These five make up core features for which developers have adopted Google Kubernetes Engine.
What is Docker?
Docker (2013) is a containerization tool. Also open-source, Docker is light on resource consumption, all the while allowing developers to automate the deployment of applications in portable containers.
Key Docker Functions
Here’s a shortlist of Docker’s core features;
- Sharable environment images through Docker Build
- Docker Assemble for programming language and framework recognition when creating containers
- Native and cloud-based toolsets to optimize developer productivity
- CI/CD tools for teams working on ascending applications with version control
- High fault tolerance with solid support for large clusters
Docker vs Kubernetes: Do You Have to Choose?
Kubernetes alone cannot start the container when you begin your project. Instead, you’d typically use Docker (or its competitors) for this part. Personally, I’ve come to accept the symbiotic relationship between the two.
“Docker creates and manages containers… then Kubernetes manages Docker.
As long as your application is simple, Docker could as well provide all the required infrastructure to keep it alive. As the application grows, possibly requiring multiple clusters and more sophisticated housekeeping, Kubernetes becomes a requirement.
The choosing part only comes into play as and when your application scales.
Pros and Cons of Docker: Containerization
Developers wouldn’t bother containerizing applications if there were no advantages associated with the technology. Let’s quickly scan through the obvious few that make choosing Docker a straightforward decision, along with some of its shortfalls.
- Easy creation: Initializing containers in Docker is fast and asks for minimal technical prowess
- Docker tools: Managing containers is easy thanks to a comprehensive suite of tools provided upfront
- Excellent support: Docker has an active community of developers to support and help troubleshoot any issues you may encounter
- No storage: Each time a container restarts, it loses the data you may have created previously. Persistence is not a default, and for novice developers, it can get complicated
- Low speed: Docker containers will never exhibit bare-metal performance figures because of the network layer through which it all loses speed. Something unheard of when using bare metal infrastructure to host applications
- No cross-platform support: The isolated nature of Docker containers makes it impossible to deploy applications in different environments than the image on which they created it
Pros and Cons of Kubernetes: Container Orchestration
Just like Docker, Kubernetes also has advantages and disadvantages that engineers have to take into consideration when using it. Let’s shed light on a few ups, and downsides for a deeper understanding of K8’s usage.
- Pods: K8 maintains Pods (containers and containerization tools) for persistence with auto-healing (recreation) in the event of an unexpected failure
- Google made: There’s an inherent confidence boost from its creation origin and the growing (largest) community around Kubernetes
- Default storage: K8 comes with cloud and SAN storage options for developers to use
- Complex setup: It requires considerable technical effort along with some time to install and configure correctly
- Overkill: Simple applications don’t require the complexity provided by Kubernetes. Who among your devs is going to say your app is ‘simple’?
- K8 talent doesn’t come cheap: DevOps engineers trained to build and maintain Kubernetes load-outs are expensive.
Even with these downsides, K8 is a future-proof technology worth migrating to. Experience has shown that creating applications from the ground-up along its standards cancels out the cost and complexity factors significantly.
Use Cases for Docker and Kubernetes
While this post focuses on Docker and Kubernetes, it’s wise to recognize that they don’t exist in isolation. Competing orchestration tools and containerization tools aside from these two claim slices of the pie.
However, there are situations for which either K8 and Docker are most appropriate. Even between the duo, some cases exclude the need for pairing. Let’s discuss these below.
When You Should Use Kubernetes
When a project has grown significantly, it requires one of the following reasons for which K8 steps up to the task;
- Near-perfect uptime: The self-healing feature of Kubernetes allows resource-hungry applications to persist regardless of how many faults your stack encounters because of the thirst.
- When trying out different containerization vendors: Because it works (at different degrees of difficulty) with almost all vendors, having K8 as the orchestrator allows freedom to explore the field. No vendor can claim your contract unless they satisfy you with their SLA after trial
- When unsure of growth potential: K8 automatically splashed resources at applications when they horizontally scale.
When You Should Use Docker
There are times for which you’d rather use Docker and its tools to host your applications. Let’s discuss some of these instances;
- When K8 is not an option: Talent gaps, API incompatibilities, and costs can funnel all usage into Docker and its tools. For orchestration, Docker Swarm could replace K8 entirely.
- When just starting out: You won’t need to pair Docker with any orchestrator when applications are still undergoing RAD growth loops. At such stages, speed trumps persistence.
- When creating CLI apps: They originally created Docker to contain CLI applications, and for these, you’ll always bump into efficiencies that boost productivity.
When You Should Use Them Together
When paired, Kubernetes and Docker make for a complimenting orchestra. for one, the slow throughput we complained about with Kubernetes’ on-the-bone deployment and conducting of container health operations.
When you have both the budget and talent to support applications that are timeless, the pair works great. You won’t meet unique downtime sources because the communities will help.
It’s also wise to recognize that both vendors have left sockets and cracks in which pieces of each other bind for better performance. Kompose by K8 is an adaptation of Docker Compose. This means using both tools was, and has become the standard.
This brings our standoff to an amicable draw. Usage points totally depend on preference. However, you won’t be using Kubernetes alone. It’s better you pair it with Docker and a data security provider for better performance than that provided by other containerization tools.