Chapter 22: Jenkins Language Projects — Java to Python

22.10 Side-by-side cheat sheet

By Ravindra Bagale · Last updated: 25 October 2026

Why: the problem

Think of a new DevOps engineer at TCS who joins a project with six services in six languages. On day one, a build is red, and the senior is on leave. You do not have time to learn six tools. You need one page that says, for each language: which file to look at, how to install, how to test, where the artifact is, where the test reports are, and which Docker image to use as an agent. That page is this lesson. We put all six languages from this chapter next to each other, then prove the table by running a small script that builds every project and prints a summary, just like a real platform team health check.

What we will build

You will read the side-by-side table, run a script that builds every badge project in its own Docker image, generate a Jenkins parallel pipeline that builds all languages at once, and use a lookup function to answer which command a language needs.

What: every term in plain English

• Build file — The file that defines the project: pom.xml, build.gradle.kts, .csproj, composer.json, requirements.txt, package.json.
• Install command — Downloads libraries.
• Test command — Runs unit tests.
• Artifact path — Where the built output lands.
• Report path — Where JUnit or TRX XML lands.
• Agent image — Docker image with the tool.
• Parallel stage — Jenkins runs several branches at the same time.
• Matrix — Jenkins runs the same stages for many values.

How: step by step

1. Print the table

   column -t -s"|" langs.txt
   

   What it does: Readable in the terminal.

   Output

   (table below)
   

2. Java Maven

   mvn -B package
   

   What it does: Report: target/surefire-reports/*.xml

   Output

   target/*.jar
   

3. Gradle

   ./gradlew build
   

   What it does: Report: build/test-results/test/*.xml

   Output

   build/libs/*.jar
   

4. .NET

   dotnet test --logger trx; dotnet publish -o out
   

   What it does: Report: TestResults/*.trx

   Output

   out/
   

5. PHP

   composer install; vendor/bin/phpunit --log-junit junit.xml
   

   What it does: Report: junit.xml

   Output

   dist/*.zip
   

6. Python

   pip install -r requirements.txt; pytest --junitxml=report.xml
   

   What it does: Report: report.xml

   Output

   wheel or image
   

7. Node

   npm ci; node --test
   

   What it does: Report: junit.xml

   Output

   *.tgz or build/
   

Example 1: The cheat sheet as a file

Stack. Bash

Goal. The cheat sheet as a file.

langs.txt

Language|Build file|Install|Test|Artifact|Agent image
Java Maven|pom.xml|mvn -B dependency:go-offline|mvn -B test|target/*.jar|maven:3.9-eclipse-temurin-17
Spring Boot|pom.xml|mvn -B dependency:go-offline|mvn -B test|target/*.jar (fat)|maven:3.9-eclipse-temurin-17
Gradle|build.gradle.kts|./gradlew dependencies|./gradlew test|build/libs/*.jar|eclipse-temurin:17-jdk
.NET|*.csproj, *.sln|dotnet restore|dotnet test|out/|mcr.microsoft.com/dotnet/sdk:8.0
PHP|composer.json|composer install|vendor/bin/phpunit|dist/*.zip|composer:2
Python|requirements.txt|pip install -r requirements.txt|pytest|image or wheel|python:3.12-slim
Node|package.json|npm ci|node --test|*.tgz|node:20-alpine

show

column -t -s"|" langs.txt

What each line does

• column -t — Align columns.
• -s"|" — Pipe is the separator.

Green output

Language     Build file        Install                         Test                Artifact           Agent image
Java Maven   pom.xml           mvn -B dependency:go-offline    mvn -B test         target/*.jar       maven:3.9-eclipse-temurin-17
Gradle       build.gradle.kts  ./gradlew dependencies          ./gradlew test      build/libs/*.jar   eclipse-temurin:17-jdk
.NET         *.csproj, *.sln   dotnet restore                  dotnet test         out/               mcr.microsoft.com/dotnet/sdk:8.0
PHP          composer.json     composer install                vendor/bin/phpunit  dist/*.zip         composer:2
Python       requirements.txt  pip install -r requirements.txt pytest              image or wheel     python:3.12-slim
Node         package.json      npm ci                          node --test         *.tgz              node:20-alpine

Expected result. One screen answers most day-one questions.

Example 2: Build every project in its own image

Stack. Docker, Bash

Goal. Build every project in its own image.

build-all.sh

#!/usr/bin/env bash
set -u
cd ~/devops-lab/ch22
run() { name=$1 image=$2 cmd=$3
  if docker run --rm -v "$PWD/$name":/w -w /w -e HOME=/tmp "$image" sh -c "$cmd" > "$name.log" 2>&1
  then echo "GREEN $name"; else echo "RED   $name (see $name.log)"; fi
}
run badge-java   maven:3.9-eclipse-temurin-17     "mvn -B -q package"
run badge-gradle eclipse-temurin:17-jdk           "./gradlew -q --no-daemon build"
run badge-dotnet mcr.microsoft.com/dotnet/sdk:8.0 "dotnet test --nologo -v q"
run badge-php    composer:2                       "composer install -q && vendor/bin/phpunit"
run badge-python python:3.12-slim                 "pip install -q -r requirements.txt && pytest -q"
run badge-node   node:20-alpine                   "npm ci --silent && node --test"

What each line does

• run() — One helper for every language.
• -v "$PWD/$name":/w — Mount the project.
• > "$name.log" — Keep the full log for red ones.
• set -u — Fail on unset variables, but keep going on red builds.

Green output

GREEN badge-java
GREEN badge-gradle
GREEN badge-dotnet
GREEN badge-php
GREEN badge-python
GREEN badge-node

Expected result. Your laptop needs only Docker to build all six languages.

Example 3: Build all languages in parallel in Jenkins

Stack. Jenkins

Goal. Build all languages in parallel in Jenkins.

Jenkinsfile

pipeline {
  agent none
  stages {
    stage('All languages') {
      parallel {
        stage('Java')   { agent { docker { image 'maven:3.9-eclipse-temurin-17' } } steps { dir('badge-java')   { sh 'mvn -B package' } } }
        stage('.NET')   { agent { docker { image 'mcr.microsoft.com/dotnet/sdk:8.0'; args '-e HOME=/tmp' } } steps { dir('badge-dotnet') { sh 'dotnet test' } } }
        stage('PHP')    { agent { docker { image 'composer:2' } } steps { dir('badge-php')    { sh 'composer install && vendor/bin/phpunit' } } }
        stage('Python') { agent { docker { image 'python:3.12-slim'; args '-e HOME=/tmp' } } steps { dir('badge-python') { sh 'pip install -r requirements.txt && pytest -q' } } }
        stage('Node')   { agent { docker { image 'node:20-alpine' } } steps { dir('badge-node')   { sh 'npm ci && node --test' } } }
      }
    }
  }
}

What each line does

• agent none — Each parallel branch picks its own image.
• parallel — Branches run at the same time.
• dir() — Each project is a folder in one monorepo.

Green output

[Java] BUILD SUCCESS
[.NET] Passed!  - Failed: 0, Passed: 3
[PHP] OK (3 tests, 3 assertions)
[Python] 4 passed in 0.30s
[Node] # pass 3
Finished: SUCCESS

Expected result. Five languages in about the time of the slowest one.

Example 4: A lookup helper for the team

Stack. Bash

Goal. A lookup helper for the team.

cmd.sh

#!/usr/bin/env bash
case "${1:-}" in
  java)   echo "mvn -B test package  | reports: target/surefire-reports" ;;
  gradle) echo "./gradlew build      | reports: build/test-results/test" ;;
  dotnet) echo "dotnet test --logger trx | reports: TestResults" ;;
  php)    echo "vendor/bin/phpunit --log-junit junit.xml" ;;
  python) echo "pytest --junitxml=report.xml" ;;
  node)   echo "npm ci && node --test" ;;
  *)      echo "usage: cmd.sh java|gradle|dotnet|php|python|node"; exit 2 ;;
esac

What each line does

• case — Pick one line by name.
• exit 2 — Wrong usage is an error.

Green output

$ ./cmd.sh dotnet
dotnet test --logger trx | reports: TestResults
$ ./cmd.sh ruby
usage: cmd.sh java|gradle|dotnet|php|python|node

Expected result. A tiny tool new joiners can run.

Verify: did it work?

1. All green

   ./build-all.sh | grep -c GREEN
   

   What it does: Six.

   Output

   6
   

2. Logs exist

   ls ~/devops-lab/ch22/*.log | wc -l
   

   What it does: One per project.

   Output

   6
   

3. Helper works

   ./cmd.sh python
   

   What it does: Answer.

   Output

   pytest --junitxml=report.xml
   

When it is red 1

RED badge-dotnet (see badge-dotnet.log)

Cause. Read the log: often HOME not writable.

Fix, step by step

1. Pass -e HOME=/tmp to the container.

When it is red 2

docker: Cannot connect to the Docker daemon

Cause. Docker not running or user not in docker group.

Fix, step by step

1. sudo systemctl start docker
2. Add the user to the docker group and log in again.

When it is red 3

Unable to find image 'composer:2' locally ... TLS handshake timeout

Cause. Network or proxy problem pulling images.

Fix, step by step

1. Retry, or use a company registry mirror.

When it is red 4

parallel: Invalid parameter 'agent'

Cause. Old Pipeline plugin or wrong nesting.

Fix, step by step

1. Update plugins; put agent inside each parallel stage.

Cleanup

1. Clean logs

   rm -f ~/devops-lab/ch22/*.log
   

   What it does: Tidy.

   Output

   (no output)
   

Practice tasks

Homework: try at home

Recap

• Every language has build file, install, test, artifact, report.
• Docker images remove install pain.
• parallel builds many at once.
• Keep a cheat sheet.
• Read the log of the red one first.

FAQ

Do I need to memorise this table?

No. Know where it is, and know the shape.

What about Go and Rust?

Same shape: go test, cargo test.

Matrix or parallel?

Matrix when the same steps run for many values; parallel when steps differ.

Why does .NET need HOME=/tmp?

Its CLI writes a cache to the home folder.

Can one agent have all tools?

Yes, but images are easier to update.

Where do I add Go?

A new row and a new run line in build-all.sh.

Interview questions

1. How do you support many languages in one Jenkins?

   Docker agents per language and a standard stage shape.

2. How do you speed up a monorepo build?

   parallel stages, caches, build only changed folders.

3. What are typical report paths?

   Maven target/surefire-reports, Gradle build/test-results, .NET TRX, pytest/npm junit.xml.

4. What is agent none?

   No global agent; stages choose.

5. How do you debug one red language in a parallel build?

   Open that branch log in Blue Ocean or the stage view.

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