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CBT Nuggets

DevOps & Platform · Beginner

Docker (Containers)

Docker popularized containers as a way to package an application and its dependencies into a portable image, then run it as an isolated process on any compatible host. Containers are the unit of deployment for most modern apps.

For IT leaders

Container fluency is now expected across IT and security teams; gaps slow every cloud migration and modernization conversation.

Why IT teams care

Where this shows up at the team level

  • Container image hygiene (base images, scanning, signing) is a recurring audit topic.
  • Operations teams need to debug containers in production, not only build them.
  • Container registries and CI/CD pipelines are shared infrastructure across product teams.

In production

Where teams encounter it

  • Local development with Docker Desktop or Podman
  • Container registries (ECR, ACR, GCR, GitHub Container Registry, Docker Hub)
  • Production runtimes on Kubernetes, ECS, or Cloud Run

How it works

How Docker actually works

  1. 01A Dockerfile describes how to build an image, layer by layer, from a base image.
  2. 02Building creates an immutable image identified by its digest; running an image creates a container process isolated by Linux namespaces and cgroups.
  3. 03Images are pushed to a registry, then pulled and run by orchestration platforms.
  4. 04Containers share the host kernel, which makes them lighter than VMs but means kernel-level vulnerabilities require host-level fixes.

In practice

Common team use cases

  • Standardizing application build artifacts across environments
  • Running multiple isolated workloads on shared hosts
  • Packaging tools, batch jobs, and legacy apps for portability

Build the capability

Each link routes to a hub that goes deeper than this definition.

Close the team gap

Turn this concept into team capability

CBT Nuggets builds expert-led team training that closes the gaps definitions only describe. Talk to sales about a plan that fits your team.