DevOps Essentials Sample App

A static site delivered through an automated build, test and deploy pipeline.

Live site · Pipeline runs · Jenkinsfile

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Overview

The project started as a course lab exercise and was reworked into a small reference for continuous delivery. The site itself is intentionally simple (plain HTML, CSS and a little JavaScript) so the focus stays on how it gets built, verified and released.

• Build: Gradle checks that the site is complete and packages it as a zip.
• Verify: GitHub Actions builds every pull request and validates the HTML.
• Publish: merges to master deploy the site to GitHub Pages.
• Release: a Jenkins pipeline promotes the artifact to staging, waits for approval, then deploys to production over SSH.

Architecture

flowchart LR
    Dev[Developer] -->|pull request| GH[GitHub]
    GH -->|on PR and push| GA[GitHub Actions]
    GA -->|merge to master| Pages[GitHub Pages]
    GH --> J[Jenkins]
    J -->|SSH| Stg[Staging]
    Stg -->|manual approval| Prod[Production]

Loading

Stage	Tool	What happens
Build	Gradle	Verifies required files, packages src/ into a zip
Verify	GitHub Actions	Runs ./gradlew build and validates src/index.html
Pages	GitHub Actions	Publishes src/ to GitHub Pages on every merge to master
Staging	Jenkins	Publishes src/ to the staging host over SSH
Production	Jenkins	Same publish step, gated by a manual approval

Tech stack

Area	Technology
Frontend	HTML, CSS (custom properties, light and dark themes), vanilla JavaScript
Build	Gradle 8.10.2 via wrapper, JDK 17
CI	GitHub Actions on ubuntu-24.04
Release	Jenkins declarative pipeline, Publish over SSH plugin
Hosting	GitHub Pages, plus SSH targets for staging and production

Project layout

.
├── src/
│   ├── index.html          Page markup, architecture diagram, config excerpts
│   ├── css/styles.css      Styles and theme tokens
│   ├── js/main.js          Theme toggle and scroll animations
│   └── favicon.svg
├── build.gradle            verifySite and siteZip tasks
├── Jenkinsfile             Build and deploy pipeline
├── .github/workflows/      CI and Pages workflow
├── gradle/wrapper/         Gradle wrapper (8.10.2)
└── LICENSE

Getting started

The site has no runtime dependencies. Open src/index.html in a browser, or serve the folder:

python3 -m http.server --directory src 8080
# or
npx serve src

Build and verify with Gradle (requires JDK 17 or newer):

./gradlew build          # verify and package
./gradlew verifySite     # only check required files
./gradlew siteZip        # only create the archive

The archive is written to build/distributions/devops-essentials-sample-app.zip.

Build details

build.gradle applies the base plugin and adds two tasks:

Task	Wired into	Purpose
verifySite	check	Fails the build if index.html, css/styles.css, js/main.js or favicon.svg is missing
siteZip	assemble	Packages src/ as a zip artifact

CI/CD

GitHub Actions

.github/workflows/ci.yml runs on pull requests and pushes to master:

1. build: sets up Temurin JDK 17 and Gradle, runs ./gradlew build, validates the HTML with html-validate, and uploads the zip as an artifact.
2. deploy-pages: runs only on pushes to master. It appends the short commit SHA to the stylesheet and script URLs so browsers never combine new HTML with cached old assets, then deploys src/ to GitHub Pages.

The workflow uses read-only repository permissions by default. Only the Pages job requests pages: write and id-token: write, and concurrent runs for the same ref are cancelled.

Jenkins

The Jenkinsfile defines three stages: Build (Gradle build and archived artifact), Deploy to staging, and Deploy to production. Both deploy stages run only on master and share a single deployTo() helper. The production stage waits behind an input step, so nothing is released without an explicit approval.

To use it, define two servers named staging and production under Manage Jenkins → System → Publish over SSH. Their credentials live in Jenkins and are never stored in this repository.

Branch protection

master is protected by a ruleset: changes go through a pull request, the build check must pass, force pushes are blocked and the branch cannot be deleted. Merged branches are deleted automatically.

Contributing

1. Create a branch from master.
2. Run ./gradlew build locally.
3. Open a pull request and wait for the build check to pass.

License

Released under the MIT License.