Understanding Kubernetes: Part 5 -Deployment

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Last updated 2 months ago

Understanding Kubernetes: Part 5 -Deployment

If you’ve been following our Kubernetes series 2025, welcome back! For new readers, check out Part 4:

What is a Deployment in Kubernetes?

A Deployment in Kubernetes is a resource that manages stateless applications by maintaining a specified number of replicas of a pod. It provides features like rolling updates, rollbacks, and scaling, ensuring high availability and declarative updates for applications. Deployments are ideal for managing applications that require consistent uptime and easy version management.

For example:

If you’re running a web application with multiple instances for high availability, you can use a Deployment to manage these replicas. A Deployment ensures the desired number of pods are always running, and if a pod crashes or a node goes down, Kubernetes automatically replaces the failed pod to maintain the application’s state.

Deployment Capabilities:

Deployments handle pod lifecycle management through ReplicaSets, offering:

Rolling Updates: Incrementally update pods without downtime.
Rollbacks: Quickly revert to a previous state if an update fails.
Scaling: Dynamically increase or decrease the number of replicas based on workload demands.
Self-healing: Automatically replace failed pods to maintain the desired state.

In my previous role:

As a Senior DevOps Engineer, I used Deployments extensively to manage microservices in a Kubernetes environment. For instance, we had a Python-based API with six replicas to ensure high availability. I utilized Deployments to perform rolling updates during new releases, ensuring zero downtime. Once, during a production update, an issue arose due to a misconfigured image. Using the rollback feature of Deployments, I quickly restored the application to its previous stable version, minimizing disruption.

Here’s a simple YAML for deploying a Deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: api-service
spec:
  replicas: 6
  selector:
    matchLabels:
      app: api
  template:
    metadata:
      labels:
        app: api
    spec:
      containers:
      - name: api-container
        image: python:3.9
        ports:
        - containerPort: 8000

This Deployment ensures six replicas of the API are running and allows seamless updates or scaling, making it an essential component for managing stateless applications in Kubernetes.

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