DevOps Introduction

What is DevOps?

DevOps is a way of building and running software in which the people who write the code and the people who run it work as one team, with automation connecting every step from a commit to production. The goal is to deliver changes quickly and safely, again and again.

Before DevOps, developers "threw code over the wall" to an operations team that deployed it weeks later, by hand. Releases were big, rare and scary. DevOps replaces that with small changes that flow through an automated pipeline many times a day.

What a DevOps workflow looks like

1. A developer pushes a small change to Git.
2. Continuous integration (CI) builds it and runs the tests automatically.
3. The build produces an artifact, usually a container image.
4. Continuous delivery (CD) deploys it to staging and then production, often gradually.
5. Monitoring shows whether the change is healthy, and a bad change is rolled back quickly.
6. The infrastructure itself is defined as code (Terraform, Kubernetes manifests) and changes the same way.

How this tutorial works

The shell and Git examples are real bash scripts: each was run on Linux and the output shown is what it printed. Run them in a terminal on Linux, macOS or Windows (WSL). Some concept examples are short Python programs you can run right here in the browser.

for stage in build test package deploy verify; do
  echo "pipeline: $stage ... ok"
done
echo "change is live"

pipeline: build ... ok
pipeline: test ... ok
pipeline: package ... ok
pipeline: deploy ... ok
pipeline: verify ... ok
change is live