Docker

Docker established the container as the standard unit of deployment. It packages an application with all its dependencies into an image that runs identically on a developer's machine, in testing, and in production, putting an end to the classic "works on my machine."

What is Docker used for?

Docker builds images from a simple recipe file (the Dockerfile), stores them on a registry like Docker Hub, and runs them as isolated containers. Docker Desktop bundles the engine, an interface, and a local Kubernetes so you can develop without installing every dependency on your machine. It has become the basic building block of nearly every modern deployment pipeline, including on AWS.

Docker or Kubernetes?

It isn't a choice: Docker creates and runs containers, Kubernetes orchestrates them at scale across dozens of servers. You start with Docker alone, then add an orchestrator once the number of containers justifies it.

What are Docker's limitations?

Since 2021, Docker Desktop has been a paid product for companies with more than 250 employees or 10 M$ in revenue, which has pushed some teams toward alternatives like Podman. Docker Hub's download quotas on the free plan can also get in the way during continuous integration.