prettier-plugin-jenkinsfile

A Prettier plugin for formatting Jenkins Declarative Pipeline files (Jenkinsfile) and Groovy files.

Uses a forked tree-sitter-groovy (extended from murtaza64/tree-sitter-groovy) for parsing, producing AST-aware formatting that understands Groovy's named parameter syntax and Jenkins DSL patterns.

Features

• terraform(), ansible(), and tofu* calls always expand named arguments one per line with trailing commas
• Short single-statement closures kept inline (e.g. retry(3) { sh 'make' })
• Multi-statement closures expanded to block format
• Triple-quoted strings (YAML pod specs) preserved verbatim
• Proper 2-space indentation throughout
• Jenkins DSL blocks (pipeline, stages, stage, steps, agent, dir, when, etc.) always kept in block form

Installation

npm install --save-dev prettier-plugin-jenkinsfile

Usage

# Format a Jenkinsfile
npx prettier --write Jenkinsfile

# Format all Jenkinsfiles in a directory
npx prettier --write '**/Jenkinsfile'

# Check formatting (CI mode)
npx prettier --check Jenkinsfile

The plugin automatically detects files named Jenkinsfile and files with .groovy or .gradle extensions.

Pre-commit / prek hook

This repo ships a pre-commit hook (also compatible with prek). Add it to your .pre-commit-config.yaml:

repos:
  - repo: https://github.com/bootswithdefer/prettier-plugin-jenkinsfile
    rev: v0.1.2
    hooks:
      - id: jenkinsfile-fmt

The hook formats files named Jenkinsfile and files with .groovy or .gradle extensions on commit. It runs Prettier with this plugin in an isolated Node environment managed by pre-commit — no Node project or global install required.

Example

Before:

#!groovy
def appName = 'my-service'
pipeline {
  agent { label 'linux' }
  stages {
    stage('deploy') {
      steps {
        script {
          terraform(workspace: 'production', auto_approve: true)
          retry(3) {
            sh './deploy.sh'
          }
        }
      }
    }
  }
}

After:

#!groovy
def appName = 'my-service'
pipeline {
  agent {
    label 'linux'
  }
  stages {
    stage('deploy') {
      steps {
        script {
          terraform(
            workspace: 'production',
            auto_approve: true,
          )
          retry(3) { sh './deploy.sh' }
        }
      }
    }
  }
}

Configuration

This plugin uses Prettier's standard configuration. Relevant options:

| Option | Default | Description | |--------|---------|-------------| | tabWidth | 2 | Indentation width | | printWidth | 80 | Line width for inline/expand decisions |

How It Works

1. Parses the file using tree-sitter-groovy (via WebAssembly)
2. Walks the concrete syntax tree (CST)
3. Emits Prettier's intermediate representation (doc IR)
4. Prettier handles line-breaking, indentation, and output

The plugin bundles a pre-compiled tree-sitter-groovy.wasm — no native dependencies required.

Limitations

• Does not format arbitrary Groovy (class definitions, complex expressions). Focused on Jenkins Pipeline DSL patterns.
• Comments attached to the end of a line may move to the next line.
• The parser handles most Declarative Pipeline patterns but may not parse highly unusual Scripted Pipeline code.

License

MIT