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Chapter 22: Jenkins Language Projects — Java to Python

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Chala mitrano, aaj aapan Jenkinsfile language-wise: Java, Spring Boot, .NET, PHP, Python, Gradle. Pratyek sathi project shape, push, Jenkins kay chalavto, green ani red. Node chapters 20–21 madhe. Ghabru naka.

What you will learn in this chapter

  • Walk each language repo from tree → push → Jenkins stages → green/red
  • Declarative Jenkinsfile per language with Build, Test, lab Live
  • Keep Node as a pointer to chapters 20 and 21
  • Side-by-side command cheat sheet

Concepts in this chapter

  1. 22.1How to read this chapter
  2. 22.2Shared Pipeline job reminder
  3. 22.3Java (Maven) — start to end
  4. 22.4Spring Boot — start to end
  5. 22.5.NET — start to end
  6. 22.6PHP — start to end
  7. 22.7Python — start to end
  8. 22.8Gradle — start to end
  9. 22.9Node.js — pointer to chapters 20 and 21
  10. 22.10Side-by-side cheat sheet
  11. 22.11Safety and honesty checklist

The chapter recap is at the end of the last concept page.

Practice Tasks

About this scenario

Suppose we are on the DevOps team at Mercado Libre, the marketplace company, working from Buenos Aires. Mateo Fernández leads the team, and we look after the seller listing API. Costs are counted in ARS. In the tasks below we do real DevOps jobs on this project using what this lesson teaches. Mercado Libre is a real company, but this project, the people, servers, IP addresses and numbers are made up for practice.

0 / 12

Easy Declarative Jenkinsfile: build and test

Why: Pipeline as code lives in Git with the app, so every change is reviewed.

What to do: Write a declarative Jenkinsfile: agent any; stage Build runs sh 'mvn -B package'; stage Test runs sh 'mvn test'.

How:
  1. Start with pipeline { and close it with } at the end.
  2. Add agent, then stages { } with one stage('Name') { steps { } } per step.
  3. Put the commands inside steps using sh '...'.
  4. Count your { and } so every block is closed, then click Check answer.

Easy GitHub Actions: test on every push

Why: Running tests on every push catches bugs before they reach main.

What to do: Write .github/workflows/ci.yml named CI that runs on push. One job test on ubuntu-latest with steps: actions/checkout@v4, actions/setup-node@v4 with node-version 20, run npm ci, run npm test.

How:
  1. Start from the top-level keys the task names.
  2. Indent child keys with 2 spaces (no tabs).
  3. Use "- " for list items and fill each value from the task.
  4. Check the colons and spacing, then click Check answer.

Medium Run the build inside a Docker agent

Why: A Docker agent gives a clean, versioned toolchain for every build.

What to do: Declarative pipeline with agent docker { image 'maven:3.9-eclipse-temurin-21' } and stage Build running sh 'mvn -B verify'.

How:
  1. Start with pipeline { and close it with } at the end.
  2. Add agent, then stages { } with one stage('Name') { steps { } } per step.
  3. Put the commands inside steps using sh '...'.
  4. Count your { and } so every block is closed, then click Check answer.

Medium Pipeline environment variables

Why: Values set once in environment are reused by every stage.

What to do: Declarative pipeline, agent any, environment with IMAGE = 'mercadolibre/seller-listing' and TAG = '1.6.6', and stage Image running sh 'docker build -t $IMAGE:$TAG .'.

How:
  1. Start with pipeline { and close it with } at the end.
  2. Add agent, then stages { } with one stage('Name') { steps { } } per step.
  3. Put the commands inside steps using sh '...'.
  4. Count your { and } so every block is closed, then click Check answer.

Medium Compose: env file and restart policy

Why: Secrets live in an env file that is not committed, and services come back after a reboot.

What to do: Write compose.yaml: service worker with image mercadolibre/seller-listing-worker:1.6.6, env_file .env, and restart: unless-stopped.

How:
  1. Start from the top-level keys the task names.
  2. Indent child keys with 2 spaces (no tabs).
  3. Use "- " for list items and fill each value from the task.
  4. Check the colons and spacing, then click Check answer.

Medium Pass environment variables

Why: The same image runs in dev and prod; only the settings change.

What to do: Run mercadolibre/seller-listing:1.6.6 detached, named seller-listing, with APP_ENV=production and PORT=9090, publishing 9090:9090.

How:
  1. Read the task and pick the tool it needs (git, docker, kubectl, terraform, ansible...).
  2. Write the tool name, then the sub-command (the action word).
  3. Add the flags the task needs, each followed by its value.
  4. Add names, files or paths at the end, then click Check answer.

Medium Always archive, alert on failure

Why: post blocks run after the stages, whatever the result.

What to do: Declarative pipeline, agent any, one stage Build with sh 'make'. Add post: always → archiveArtifacts artifacts: 'build/**'; failure → echo 'Build failed'.

How:
  1. Start with pipeline { and close it with } at the end.
  2. Add agent, then stages { } with one stage('Name') { steps { } } per step.
  3. Put the commands inside steps using sh '...'.
  4. Count your { and } so every block is closed, then click Check answer.

Medium Deploy only from main

Why: Feature branches are built and tested but never deployed.

What to do: Declarative pipeline, agent any, stage Deploy with when { branch 'main' } and steps sh './deploy.sh sa-east-1'.

How:
  1. Start with pipeline { and close it with } at the end.
  2. Add agent, then stages { } with one stage('Name') { steps { } } per step.
  3. Put the commands inside steps using sh '...'.
  4. Count your { and } so every block is closed, then click Check answer.

Hard Parallel test stages

Why: Running unit and lint at the same time halves feedback time.

What to do: Declarative pipeline, agent any, stage Checks containing parallel with stage Unit (sh 'npm test') and stage Lint (sh 'npm run lint').

How:
  1. Start with pipeline { and close it with } at the end.
  2. Add agent, then stages { } with one stage('Name') { steps { } } per step.
  3. Put the commands inside steps using sh '...'.
  4. Count your { and } so every block is closed, then click Check answer.

Hard Use Jenkins credentials safely

Why: withCredentials masks the password and removes it after the block.

What to do: Inside stage Push steps, use withCredentials with usernamePassword(credentialsId: 'reg-cred', usernameVariable: 'U', passwordVariable: 'P') and run sh 'echo $P | docker login -u $U --password-stdin registry.mercadolibre.example.com'. Wrap it in a full declarative pipeline with agent any.

How:
  1. Start with pipeline { and close it with } at the end.
  2. Add agent, then stages { } with one stage('Name') { steps { } } per step.
  3. Put the commands inside steps using sh '...'.
  4. Count your { and } so every block is closed, then click Check answer.

Hard Manual approval before production

Why: A human sign-off stops an accidental production release.

What to do: Declarative pipeline, agent any, stage Prod with input message 'Deploy to production?' and steps sh './deploy.sh prod'.

How:
  1. Start with pipeline { and close it with } at the end.
  2. Add agent, then stages { } with one stage('Name') { steps { } } per step.
  3. Put the commands inside steps using sh '...'.
  4. Count your { and } so every block is closed, then click Check answer.

Hard Matrix build on three Python versions

Why: A matrix tests every supported version in parallel.

What to do: Write a workflow (on: push) with job test on ubuntu-latest using strategy.matrix.python with "3.10", "3.11", "3.12". Steps: actions/checkout@v4, actions/setup-python@v5 with python-version ${{ matrix.python }}, run pytest.

How:
  1. Start from the top-level keys the task names.
  2. Indent child keys with 2 spaces (no tabs).
  3. Use "- " for list items and fill each value from the task.
  4. Check the colons and spacing, then click Check answer.

See all DevOps practice tasks in the Task Hub →

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