devsimsek's Blog

As developers, we’re constantly faced with choices about which tools to use for our projects. One of the most common questions I get from fellow developers is: “Should I use Docker or Kubernetes?” The answer, as with most things in tech, is: it depends.

Understanding the Basics

Docker: The Container Pioneer

Docker is a platform that allows you to package your application and all its dependencies into a standardized unit called a container. These containers are isolated, lightweight, and contain everything needed to run the application.

# Simple example of running a Docker container
docker run -d -p 80:80 nginx

Docker makes it incredibly easy to create, deploy, and run applications using containers. It solves the infamous “it works on my machine” problem by ensuring consistency across multiple development, testing, and production environments.

Kubernetes: The Container Orchestra Conductor

Kubernetes (K8s) is a container orchestration platform that automates the deployment, scaling, and management of containerized applications. It builds upon the container concept that Docker popularized.

# Simple Kubernetes deployment example
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

Think of Kubernetes as the system that manages many containers across multiple machines, handling things like scaling, failover, deployment patterns, and load balancing.

When to Use Docker Alone

Docker by itself is ideal when:

• You’re developing applications locally on your machine
• You have a simple application architecture with just a few services
• You’re running small-scale projects that don’t need complex scaling
• You need a quick development environment setup
• You’re in the early stages of containerization and learning the ropes
• Your application runs on a single server

I often use Docker alone for my personal projects or when I’m prototyping something new. It provides just enough isolation and reproducibility without the complexity of a full orchestration system.

When to Use Kubernetes

Kubernetes shines when:

• You’re running microservices at scale with many containers
• You need high availability with no downtime
• Your application requires automatic scaling based on demand
• You want sophisticated deployment strategies (blue/green, canary)
• You need self-healing infrastructure that recovers from failures
• You’re managing applications across multiple environments or clouds
• Your team has the resources and knowledge to manage the complexity

For larger applications I’ve worked on, Kubernetes has been invaluable. Once you get past the initial learning curve, it provides powerful tools for managing complex deployments.

A Middle Ground: Docker Compose

Before jumping straight from Docker to Kubernetes, consider Docker Compose:

# Simple Docker Compose example
version: '3'
services:
  web:
    image: nginx
    ports:
      - "80:80"
  db:
    image: postgres
    environment:
      POSTGRES_PASSWORD: example

Docker Compose lets you define and run multi-container applications on a single host. It’s significantly simpler than Kubernetes while offering more organization than plain Docker commands.

Real-World Decision Framework

When deciding between Docker and Kubernetes, I ask myself these questions:

1. Scale: How many containers will I need to manage?
2. Complexity: How complex is my application architecture?
3. Team: Do we have the expertise to manage Kubernetes?
4. Growth: How quickly will our application need to scale?
5. Requirements: Do we need advanced features like auto-scaling and self-healing?

My Personal Experience

I started with just Docker for most of my projects. As complexity grew, I moved to Docker Compose, which served me well for medium-sized applications with 5-10 services running on a single server.

It wasn’t until I worked on a project that needed to handle unpredictable traffic spikes that I really appreciated what Kubernetes offers. The ability to automatically scale based on CPU usage saved us during several traffic surges that would have crashed our previous setup.

That said, Kubernetes came with its own challenges – the learning curve is steep, and troubleshooting can be complex. It’s definitely overkill for simpler applications.

Also, I don’t like to suggest kubernetes.

Conclusion

Docker is for containers. Kubernetes is for orchestrating many containers.

Start with Docker. If your needs grow beyond what Docker alone can easily manage, consider Docker Compose as an intermediate step. Graduate to Kubernetes when you have clear requirements that justify its complexity.

Remember, the goal is to deliver value to your users, not to use the most complex or trendy tools. Choose the technology that solves your specific problems with the minimum necessary complexity.

What has your experience been with these tools? Let me know in the comments!

Until tomorrow,

PS: if you want to oversimplify things, I would suggest you take look at nix!