MegaLinter, by

MegaLinter is an Open-Source tool for CI/CD workflows that analyzes the consistency of your code, IAC, configuration, and scripts in your repository sources, to ensure all your projects sources are clean and formatted whatever IDE/toolbox is used by their developers, powered by OX Security.

Supporting 62 languages, 23 formats, 20 tooling formats and ready to use out of the box, as a GitHub action or any CI system, highly configurable and free for all uses.

MegaLinter has native integrations with many of the major CI/CD tools of the market.

Upgrade to MegaLinter v8 :)

Before going below, see Online Documentation Web Site which has a much easier user navigation than this README

Table of Contents

• Why MegaLinter
• Quick Start
• Supported Linters
  • Languages
  • Formats
  • Tooling formats
  • Other
• Installation
  • Assisted installation
  • Which version to use ?
  • GitHub Action
  • GitLab CI
    • Manual Setup
    • Using R2Devops
  • Azure Pipelines
  • Bitbucket Pipelines
  • Jenkins
  • Concourse
    • Pipeline step
    • Use it as reusable task
  • Drone CI
    • (Optional) Adjusting trigger rules
  • Docker container
  • Run MegaLinter locally
• Configuration
  • .mega-linter.yml file
  • Common variables
  • Activation and deactivation
  • Filter linted files
  • Apply fixes
    • Apply fixes issues
    • Notes
  • Linter specific variables
  • Pre-commands
  • Post-commands
  • Environment variables security
    • Secured env variables
    • Secured configuration examples
    • Default secured variables
    • Unhide variables for linters
  • CLI lint mode
• Reporters
• Flavors
• Badge
  • Markdown
  • reStructuredText
• Plugins
  • External Plugins Catalog
  • Use external plugins
    • Example
  • Create your own plugin
    • Limitations
• They talk about MegaLinter
  • English articles
  • French articles
  • Videos
  • Web Sites
  • Linters
• Frequently Asked Questions
• How to contribute
• Special thanks
  • Maintainers
  • Contributors
  • Open-source teams
  • Super-Linter team
• License
• MegaLinter vs Super-Linter
  • Security
  • Performances
  • More languages and formats linted
  • Automatically apply formatting and fixes
  • Run locally
  • Reports
    • Capabilities
    • Additional Reporters
  • Enhanced Configuration
  • Enhanced Documentation
  • Plugins management
  • Simplify architecture and evolutive maintenance
  • Improve robustness & stability

Why MegaLinter

Projects need to contain clean code, in order to avoid technical debt, that makes evolutive maintenance harder and time consuming.

By using code formatters and code linters, you ensure that your code base is easier to read and respects best practices, from the kick-off to each step of the project lifecycle

Not all developers have the good habit to use linters in their IDEs, making code reviews harder and longer to process

By using MegaLinter, you'll enjoy the following benefits for you and your team:

• At each pull request it will automatically analyze all updated code in all languages
• Reading error logs, developers learn best practices of the language they're using
• MegaLinter documentation provides the list of IDE plugins integrating each linter, so developers know which linter and plugins to install
• MegaLinter is ready out of the box after a quick setup
• Formatting and fixes can be automatically applied on the git branch or provided in reports
• This tool is 100% open-source and free for all uses (personal, professional, public and private repositories)
• MegaLinter can run on any CI tool and be run locally: no need to authorize an external application, and your code base never leaves your tooling ecosystem

Quick Start

• Run npx mega-linter-runner --install to generate configuration files (you need node.js to be installed)
• Commit, push, and create a pull request
• Watch !

Notes:

• This repo is a hard-fork of GitHub Super-Linter, rewritten in python to add lots of additional features
• If you are a Super-Linter user, you can transparently switch to MegaLinter and keep the same configuration (just replace super-linter/super-linter@v3 by oxsecurity/megalinter@v8 in your GitHub Action YML file, like on this PR)
• If you want to use MegaLinter extra features (recommended), please take 5 minutes to use MegaLinter assisted installation
• For a hand-holdy example of getting started with mega-linter check out this blog post by Alec Johnson

Supported Linters

All linters are integrated in the MegaLinter docker image, which is frequently upgraded with their latest versions

Languages

	Language	Linter	Additional
	BASH	bash-execBASH_EXEC
	BASH	shellcheckBASH_SHELLCHECK
	BASH	shfmtBASH_SHFMT
	C	cpplintC_CPPLINT
	C	clang-formatC_CLANG_FORMAT
	CLOJURE	clj-kondoCLOJURE_CLJ_KONDO
	CLOJURE	cljstyleCLOJURE_CLJSTYLE
	COFFEE	coffeelintCOFFEE_COFFEELINT
	C++ (CPP)	cpplintCPP_CPPLINT
	C++ (CPP)	clang-formatCPP_CLANG_FORMAT
	C# (CSHARP)	dotnet-formatCSHARP_DOTNET_FORMAT
	C# (CSHARP)	csharpierCSHARP_CSHARPIER
	C# (CSHARP)	roslynatorCSHARP_ROSLYNATOR
	DART	dartanalyzerDART_DARTANALYZER
	GO	golangci-lintGO_GOLANGCI_LINT
	GO	reviveGO_REVIVE
	GROOVY	npm-groovy-lintGROOVY_NPM_GROOVY_LINT
	JAVA	checkstyleJAVA_CHECKSTYLE
	JAVA	pmdJAVA_PMD
	JAVASCRIPT	eslintJAVASCRIPT_ES
	JAVASCRIPT	standardJAVASCRIPT_STANDARD
	JAVASCRIPT	prettierJAVASCRIPT_PRETTIER
	JSX	eslintJSX_ESLINT
	KOTLIN	ktlintKOTLIN_KTLINT
	KOTLIN	detektKOTLIN_DETEKT
	LUA	luacheckLUA_LUACHECK
	LUA	seleneLUA_SELENE
	LUA	styluaLUA_STYLUA
	MAKEFILE	checkmakeMAKEFILE_CHECKMAKE
	PERL	perlcriticPERL_PERLCRITIC
	PHP	phpcsPHP_PHPCS
	PHP	phpstanPHP_PHPSTAN
	PHP	psalmPHP_PSALM
	PHP	phplintPHP_PHPLINT
	PHP	php-cs-fixerPHP_PHPCSFIXER
	POWERSHELL	powershellPOWERSHELL_POWERSHELL
	POWERSHELL	powershell_formatterPOWERSHELL_POWERSHELL_FORMATTER
	PYTHON	pylintPYTHON_PYLINT
	PYTHON	blackPYTHON_BLACK
	PYTHON	flake8PYTHON_FLAKE8
	PYTHON	isortPYTHON_ISORT
	PYTHON	banditPYTHON_BANDIT
	PYTHON	mypyPYTHON_MYPY
	PYTHON	pyrightPYTHON_PYRIGHT
	PYTHON	ruffPYTHON_RUFF
	R	lintrR_LINTR
	RAKU	rakuRAKU_RAKU
	RUBY	rubocopRUBY_RUBOCOP
	RUST	clippyRUST_CLIPPY
	SALESFORCE	sfdx-scanner-apexSALESFORCE_SFDX_SCANNER_APEX
	SALESFORCE	sfdx-scanner-auraSALESFORCE_SFDX_SCANNER_AURA
	SALESFORCE	sfdx-scanner-lwcSALESFORCE_SFDX_SCANNER_LWC
	SALESFORCE	lightning-flow-scannerSALESFORCE_LIGHTNING_FLOW_SCANNER
	SCALA	scalafixSCALA_SCALAFIX
	SQL	sqlfluffSQL_SQLFLUFF
	SQL	tsqllintSQL_TSQLLINT
	SWIFT	swiftlintSWIFT_SWIFTLINT
	TSX	eslintTSX_ESLINT
	TYPESCRIPT	eslintTYPESCRIPT_ES
	TYPESCRIPT	ts-standardTYPESCRIPT_STANDARD
	TYPESCRIPT	prettierTYPESCRIPT_PRETTIER
	Visual Basic .NET (VBDOTNET)	dotnet-formatVBDOTNET_DOTNET_FORMAT

Formats

	Format	Linter	Additional
	CSS	stylelintCSS_STYLELINT
	ENV	dotenv-linterENV_DOTENV_LINTER
	GRAPHQL	graphql-schema-linterGRAPHQL_GRAPHQL_SCHEMA_LINTER
	HTML	djlintHTML_DJLINT
	HTML	htmlhintHTML_HTMLHINT
	JSON	jsonlintJSON_JSONLINT
	JSON	eslint-plugin-jsoncJSON_ESLINT_PLUGIN_JSONC
	JSON	v8rJSON_V8R
	JSON	prettierJSON_PRETTIER
	JSON	npm-package-json-lintJSON_NPM_PACKAGE_JSON_LINT
	LATEX	chktexLATEX_CHKTEX
	MARKDOWN	markdownlintMARKDOWN_MARKDOWNLINT
	MARKDOWN	remark-lintMARKDOWN_REMARK_LINT
	MARKDOWN	markdown-link-checkMARKDOWN_MARKDOWN_LINK_CHECK
	MARKDOWN	markdown-table-formatterMARKDOWN_MARKDOWN_TABLE_FORMATTER
	PROTOBUF	protolintPROTOBUF_PROTOLINT
	RST	rst-lintRST_RST_LINT
	RST	rstcheckRST_RSTCHECK
	RST	rstfmtRST_RSTFMT
	XML	xmllintXML_XMLLINT
	YAML	prettierYAML_PRETTIER
	YAML	yamllintYAML_YAMLLINT
	YAML	v8rYAML_V8R

Tooling formats

	Tooling format	Linter	Additional
	ACTION	actionlintACTION_ACTIONLINT
	ANSIBLE	ansible-lintANSIBLE_ANSIBLE_LINT
	API	spectralAPI_SPECTRAL
	ARM	arm-ttkARM_ARM_TTK
	BICEP	bicep_linterBICEP_BICEP_LINTER
	CLOUDFORMATION	cfn-lintCLOUDFORMATION_CFN_LINT
	DOCKERFILE	hadolintDOCKERFILE_HADOLINT
	EDITORCONFIG	editorconfig-checkerEDITORCONFIG_EDITORCONFIG_CHECKER
	GHERKIN	gherkin-lintGHERKIN_GHERKIN_LINT
	KUBERNETES	kubeconformKUBERNETES_KUBECONFORM
	KUBERNETES	helmKUBERNETES_HELM
	KUBERNETES	kubescapeKUBERNETES_KUBESCAPE
	PUPPET	puppet-lintPUPPET_PUPPET_LINT
	SNAKEMAKE	snakemakeSNAKEMAKE_LINT
	SNAKEMAKE	snakefmtSNAKEMAKE_SNAKEFMT
	TEKTON	tekton-lintTEKTON_TEKTON_LINT
	TERRAFORM	tflintTERRAFORM_TFLINT
	TERRAFORM	terrascanTERRAFORM_TERRASCAN
	TERRAFORM	terragruntTERRAFORM_TERRAGRUNT
	TERRAFORM	terraform-fmtTERRAFORM_TERRAFORM_FMT

Other

	Code quality checker	Linter	Additional
	COPYPASTE	jscpdCOPYPASTE_JSCPD
	REPOSITORY	checkovREPOSITORY_CHECKOV
	REPOSITORY	devskimREPOSITORY_DEVSKIM
	REPOSITORY	dustilockREPOSITORY_DUSTILOCK
	REPOSITORY	git_diffREPOSITORY_GIT_DIFF
	REPOSITORY	gitleaksREPOSITORY_GITLEAKS
	REPOSITORY	grypeREPOSITORY_GRYPE
	REPOSITORY	kicsREPOSITORY_KICS
	REPOSITORY	ls-lintREPOSITORY_LS_LINT
	REPOSITORY	secretlintREPOSITORY_SECRETLINT
	REPOSITORY	semgrepREPOSITORY_SEMGREP
	REPOSITORY	syftREPOSITORY_SYFT
	REPOSITORY	trivyREPOSITORY_TRIVY
	REPOSITORY	trivy-sbomREPOSITORY_TRIVY_SBOM
	REPOSITORY	trufflehogREPOSITORY_TRUFFLEHOG
	SPELL	cspellSPELL_CSPELL
	SPELL	proselintSPELL_PROSELINT
	SPELL	valeSPELL_VALE
	SPELL	lycheeSPELL_LYCHEE

Installation

Assisted installation

Just run npx mega-linter-runner --install at the root of your repository and answer questions, it will generate ready to use configuration files for MegaLinter :)

Which version to use ?

The following instructions examples are using latest MegaLinter stable version (v8 , always corresponding to the latest release)

• Docker image: oxsecurity/megalinter:v8
• GitHub Action: oxsecurity/megalinter@v8

You can also use beta version (corresponding to the content of main branch)

• Docker image: oxsecurity/megalinter:beta
• GitHub Action: oxsecurity/megalinter@beta

GitHub Action

1. Create a new file in your repository called .github/workflows/mega-linter.yml
2. Copy the example workflow from below into that new file, no extra configuration required
3. Commit that file to a new branch
4. Open up a pull request and observe the action working
5. Enjoy your more stable, and cleaner code base

NOTES:

• If you pass the Environment variable GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} in your workflow, then the MegaLinter will mark the status of each individual linter run in the Checks section of a pull request. Without this you will only see the overall status of the full run. There is no need to set the GitHub Secret as it's automatically set by GitHub, it only needs to be passed to the action.
• You can also use it outside of GitHub Actions (CircleCI, Azure Pipelines, Jenkins, GitLab, or even locally with a docker run) , and have status on Github Pull Request if GITHUB_TARGET_URL environment variable exists.

In your repository you should have a .github/workflows folder with GitHub Action similar to below:

• .github/workflows/mega-linter.yml

---
# MegaLinter GitHub Action configuration file
# More info at https://megalinter.io
name: MegaLinter

on:
  # Trigger mega-linter at every push. Action will also be visible from Pull Requests to main
  push: # Comment this line to trigger action only on pull-requests (not recommended if you don't pay for GH Actions)
  pull_request:
    branches: [master, main]

env: # Comment env block if you don't want to apply fixes
  # Apply linter fixes configuration
  APPLY_FIXES: all # When active, APPLY_FIXES must also be defined as environment variable (in github/workflows/mega-linter.yml or other CI tool)
  APPLY_FIXES_EVENT: pull_request # Decide which event triggers application of fixes in a commit or a PR (pull_request, push, all)
  APPLY_FIXES_MODE: commit # If APPLY_FIXES is used, defines if the fixes are directly committed (commit) or posted in a PR (pull_request)

concurrency:
  group: ${{ github.ref }}-${{ github.workflow }}
  cancel-in-progress: true

jobs:
  megalinter:
    name: MegaLinter
    runs-on: ubuntu-latest
    permissions:
      # Give the default GITHUB_TOKEN write permission to commit and push, comment issues & post new PR
      # Remove the ones you do not need
      contents: write
      issues: write
      pull-requests: write
    steps:
      # Git Checkout
      - name: Checkout Code
        uses: actions/checkout@v4
        with:
          token: ${{ secrets.PAT || secrets.GITHUB_TOKEN }}
          fetch-depth: 0 # If you use VALIDATE_ALL_CODEBASE = true, you can remove this line to improve performances

      # MegaLinter
      - name: MegaLinter
        id: ml
        # You can override MegaLinter flavor used to have faster performances
        # More info at https://megalinter.io/flavors/
        uses: oxsecurity/megalinter@v8
        env:
          # All available variables are described in documentation
          # https://megalinter.io/configuration/
          VALIDATE_ALL_CODEBASE: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' }} # Validates all source when push on main, else just the git diff with main. Override with true if you always want to lint all sources
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          # ADD YOUR CUSTOM ENV VARIABLES HERE OR DEFINE THEM IN A FILE .mega-linter.yml AT THE ROOT OF YOUR REPOSITORY
          # DISABLE: COPYPASTE,SPELL # Uncomment to disable copy-paste and spell checks

      # Upload MegaLinter artifacts
      - name: Archive production artifacts
        if: success() || failure()
        uses: actions/upload-artifact@v4
        with:
          name: MegaLinter reports
          path: |
            megalinter-reports
            mega-linter.log

      # Create pull request if applicable (for now works only on PR from same repository, not from forks)
      - name: Create Pull Request with applied fixes
        id: cpr
        if: steps.ml.outputs.has_updated_sources == 1 && (env.APPLY_FIXES_EVENT == 'all' || env.APPLY_FIXES_EVENT == github.event_name) && env.APPLY_FIXES_MODE == 'pull_request' && (github.event_name == 'push' || github.event.pull_request.head.repo.full_name == github.repository) && !contains(github.event.head_commit.message, 'skip fix')
        uses: peter-evans/create-pull-request@v6
        with:
          token: ${{ secrets.PAT || secrets.GITHUB_TOKEN }}
          commit-message: "[MegaLinter] Apply linters automatic fixes"
          title: "[MegaLinter] Apply linters automatic fixes"
          labels: bot
      - name: Create PR output
        if: steps.ml.outputs.has_updated_sources == 1 && (env.APPLY_FIXES_EVENT == 'all' || env.APPLY_FIXES_EVENT == github.event_name) && env.APPLY_FIXES_MODE == 'pull_request' && (github.event_name == 'push' || github.event.pull_request.head.repo.full_name == github.repository) && !contains(github.event.head_commit.message, 'skip fix')
        run: |
          echo "Pull Request Number - ${{ steps.cpr.outputs.pull-request-number }}"
          echo "Pull Request URL - ${{ steps.cpr.outputs.pull-request-url }}"

      # Push new commit if applicable (for now works only on PR from same repository, not from forks)
      - name: Prepare commit
        if: steps.ml.outputs.has_updated_sources == 1 && (env.APPLY_FIXES_EVENT == 'all' || env.APPLY_FIXES_EVENT == github.event_name) && env.APPLY_FIXES_MODE == 'commit' && github.ref != 'refs/heads/main' && (github.event_name == 'push' || github.event.pull_request.head.repo.full_name == github.repository) && !contains(github.event.head_commit.message, 'skip fix')
        run: sudo chown -Rc $UID .git/
      - name: Commit and push applied linter fixes
        if: steps.ml.outputs.has_updated_sources == 1 && (env.APPLY_FIXES_EVENT == 'all' || env.APPLY_FIXES_EVENT == github.event_name) && env.APPLY_FIXES_MODE == 'commit' && github.ref != 'refs/heads/main' && (github.event_name == 'push' || github.event.pull_request.head.repo.full_name == github.repository) && !contains(github.event.head_commit.message, 'skip fix')
        uses: stefanzweifel/git-auto-commit-action@v4
        with:
          branch: ${{ github.event.pull_request.head.ref || github.head_ref || github.ref }}
          commit_message: "[MegaLinter] Apply linters fixes"
          commit_user_name: megalinter-bot
          commit_user_email: [email protected]

GitLab CI

Manual setup

Create or update .gitlab-ci.yml file at the root of your repository

# MegaLinter GitLab CI job configuration file
# More info at https://megalinter.io/

mega-linter:
  stage: test
  # You can override MegaLinter flavor used to have faster performances
  # More info at https://megalinter.io/flavors/
  image: oxsecurity/megalinter:v8
  script: [ "true" ] # if script: ["true"] doesn't work, you may try ->  script: [ "/bin/bash /entrypoint.sh" ]
  variables:
    # All available variables are described in documentation
    # https://megalinter.io/configuration/
    DEFAULT_WORKSPACE: $CI_PROJECT_DIR
    # ADD YOUR CUSTOM ENV VARIABLES HERE TO OVERRIDE VALUES OF .mega-linter.yml AT THE ROOT OF YOUR REPOSITORY
  artifacts:
    when: always
    paths:
      - megalinter-reports
    expire_in: 1 week

Create a Gitlab access token and define it in a variable GITLAB_ACCESS_TOKEN_MEGALINTER in the project CI/CD masked variables. Make sure your token (e.g. if a project token) as the appropriate role for commenting a merge request (at least developer).

Using R2Devops

Our friends at R2Devops have packaged a Gitlab-CI MegaLinter workflow on their open-source templates marketplace, and it can post MegaLinter results in Gitlab Code Quality Reports !

Azure Pipelines

Use the following Azure Pipelines YAML template

Add the following job in your azure-pipelines.yaml file

  # Run MegaLinter to detect linting and security issues
  - job: MegaLinter
    pool:
      vmImage: ubuntu-latest
    steps:
      # Checkout repo
      - checkout: self

      # Pull MegaLinter docker image
      - script: docker pull oxsecurity/megalinter:v8
        displayName: Pull MegaLinter

      # Run MegaLinter
      - script: |
          docker run -v $(System.DefaultWorkingDirectory):/tmp/lint \
            --env-file <(env | grep -e SYSTEM_ -e BUILD_ -e TF_ -e AGENT_) \
            -e SYSTEM_ACCESSTOKEN=$(System.AccessToken) \
            -e GIT_AUTHORIZATION_BEARER=$(System.AccessToken) \
            oxsecurity/megalinter:v8
        displayName: Run MegaLinter

      # Upload MegaLinter reports
      - task: PublishPipelineArtifact@1
        condition: succeededOrFailed()
        displayName: Upload MegaLinter reports
        inputs:
          targetPath: "$(System.DefaultWorkingDirectory)/megalinter-reports/"
          artifactName: MegaLinterReport

To benefit from Pull Request comments, please follow configuration instructions

You can also follow this detailed tutorial by DonKoning

Bitbucket Pipelines

1. Create a bitbucket-pipelines.yml file on the root directory of your repository

2. Copy and paste the following template or add the step to your existing pipeline.

image: atlassian/default-image:3
pipelines:
  default:
    - parallel:
      - step:
          name: Run MegaLinter
          image: oxsecurity/megalinter:v8
          script:
            - export DEFAULT_WORKSPACE=$BITBUCKET_CLONE_DIR && bash /entrypoint.sh
          artifacts:
            -  megalinter-reports/**

Jenkins

Add the following stage in your Jenkinsfile

You may activate File.io reporter or E-mail reporter to access detailed logs and fixed source

// Lint with MegaLinter: https://megalinter.io/
stage('MegaLinter') {
    agent {
        docker {
            image 'oxsecurity/megalinter:v8'
            args "-u root -e VALIDATE_ALL_CODEBASE=true -v ${WORKSPACE}:/tmp/lint --entrypoint=''"
            reuseNode true
        }
    }
    steps {
        sh '/entrypoint.sh'
    }
    post {
        always {
            archiveArtifacts allowEmptyArchive: true, artifacts: 'mega-linter.log,megalinter-reports/**/*', defaultExcludes: false, followSymlinks: false
        }
    }
}

CloudBees themselves made a nice tutorial about how to use MegaLinter with Jenkins !

Concourse

Pipeline step

Use the following job.step in your pipeline template

Note: make sure you have job.plan.get step which gets repo containing your repository as shown in example

---

  - name: linting
    plan:
      - get: repo
      - task: linting
        config:
          platform: linux
          image_resource:
            type: docker-image
            source:
              repository: oxsecurity/megalinter
              tag: v8
          inputs:
            - name: repo
          run:
            path: bash
            args:
            - -cxe
            - |
              cd repo
              export DEFAULT_WORKSPACE=$(pwd)
              bash -ex /entrypoint.sh
              ## doing this because concourse doesn't work as other CI systems
          # params:
            # PARALLEL: true
            # DISABLE: SPELL
            # APPLY_FIXES: all
            # DISABLE_ERRORS: true
            # VALIDATE_ALL_CODEBASE: true

OR

Use it as reusable task

Create reusable concourse task which can be used with multiple pipelines

1. Create task file task-linting.yaml

---
platform: linux
image_resource:
  type: docker-image
  source:
    repository: oxsecurity/megalinter
    tag: v8

inputs:
- name: repo

## uncomment this if you want reports as task output
# output:
# - name: reports
#   path: repo/megalinter-reports

run:
  path: bash
  args:
  - -cxe
  - |
    cd repo
    export DEFAULT_WORKSPACE=$(pwd)
    bash -ex /entrypoint.sh

2. Use that task-linting.yaml task in pipeline

Note:

1. make sure task-linting.yaml is available in that repo input at root

2. task output is not shown here

resources:

  - name: linting
    plan:
      - get: repo
      - task: linting
        file: repo/task-linting.yaml
        # params:
        #   PARALLEL: true
        #   DISABLE: SPELL
        #   APPLY_FIXES: all
        #   DISABLE_ERRORS: true
        #   VALIDATE_ALL_CODEBASE: true

Drone CI

Warning: Drone CI support is experimental and is undergoing heavy modifications (see issue #2047).

1. Create a .drone.yml file on the root directory of your repository

2. Copy and paste the following template:

kind: pipeline
type: docker
name: MegaLinter

workspace:
  path: /tmp/lint

steps:

- name: megalinter
  image: oxsecurity/megalinter:v8
  environment:
    DEFAULT_WORKSPACE: /tmp/lint

This uses the Drone CI docker runner, so it's needed to install and configure it beforehand on your Drone CI server.

(Optional) Adjusting trigger rules

The Drone CI workflow should trigger automatically for every scenario (push, pull request, sync) however, you can optionally change this behavior by changing the trigger. For example:

kind: pipeline
type: docker
name: MegaLinter

workspace:
  path: /tmp/lint

steps:

- name: megalinter
  image: oxsecurity/megalinter:v8
  environment:
    DEFAULT_WORKSPACE: /tmp/lint

trigger:
  event:
  - push

The workflow above should only trigger on push, not on any other situation. For more information about how to configure Drone CI trigger rules, click here.

Docker container

You can also run megalinter with its Docker container, just execute this command:

docker run --rm -v /var/run/docker.sock:/var/run/docker.sock:rw -v $(pwd):/tmp/lint:rw oxsecurity/megalinter:v8

No extra arguments are needed, however, megalinter will lint all of the files inside the /tmp/lint folder, so it may be needed to configure your tool of choice to use the /tmp/lint folder as workspace. This can also be changed:

Example:

docker run --rm -v /var/run/docker.sock:/var/run/docker.sock:rw -v $(pwd):/example/folder:rw oxsecurity/megalinter:v8

Run MegaLinter locally

You can use mega-linter-runner to locally run MegaLinter with the same configuration defined in .mega-linter.yml file

See mega-linter-runner installation instructions

Example

npx mega-linter-runner --flavor salesforce -e "'ENABLE=DOCKERFILE,MARKDOWN,YAML'" -e 'SHOW_ELAPSED_TIME=true'

Note: You can also use such command line in your custom CI/CD pipelines

Configuration

.mega-linter.yml file

MegaLinter configuration variables are defined in a .mega-linter.yml file at the root of the repository or with environment variables. You can see an example config file in this repo: .mega-linter.yml

Configuration is assisted with autocompletion and validation in most commonly used IDEs, thanks to JSON schema stored on schemastore.org

• VSCode: You need a VSCode extension like Red Hat YAML
• IDEA family: Auto-completion natively supported

You can also define variables as environment variables.

• In case a variable exists in both ENV and .mega-linter.yml file, priority is given to ENV variable.

Common variables

Activation and deactivation

MegaLinter have all linters enabled by default, but allows to enable only some, or disable only some

• If ENABLE isn't set, all descriptors are activated by default. If set, all linters of listed descriptors will be activated by default
• If ENABLE_LINTERS is set, only listed linters will be processed
• If DISABLE is set, the linters in the listed descriptors will be skipped
• If DISABLE_LINTERS is set, the listed linters will be skipped
• If DISABLE_ERRORS_LINTERS is set, the listed linters will be run, but if errors are found, they will be considered as non blocking

Examples:

• Run all javascript and groovy linters except STANDARD javascript linter. DevSkim errors will be non-blocking

ENABLE: JAVASCRIPT,GROOVY
DISABLE_LINTERS: JAVASCRIPT_STANDARD
DISABLE_ERRORS_LINTERS: REPOSITORY_DEVSKIM

• Run all linters except PHP linters (PHP_BUILTIN, PHP_PHPCS, PHP_PHPSTAN, PHP_PSALM)

DISABLE: PHP

• Run all linters except PHP_PHPSTAN and PHP_PSALM linters

DISABLE_LINTERS:
  - PHP_PHPSTAN
  - PHP_PSALM

Filter linted files

If you need to lint only a folder or exclude some files from linting, you can use optional environment parameters FILTER_REGEX_INCLUDE and FILTER_REGEX_EXCLUDE You can apply filters to a single linter by defining variable <LINTER_KEY>_FILTER_REGEX_INCLUDE and <LINTER_KEY>_FILTER_REGEX_EXCLUDE

Examples:

• Lint only src folder: FILTER_REGEX_INCLUDE: (src/)
• Don't lint files inside test and example folders: FILTER_REGEX_EXCLUDE: (test/|examples/)
• Don't lint javascript files inside test folder: FILTER_REGEX_EXCLUDE: (test/.*\.js)

Warning: not applicable with linters using CLI lint mode project (see details)

Apply fixes

Mega-linter is able to apply fixes provided by linters. To use this capability, you need 3 env variables defined at top level

• APPLY_FIXES: all to apply fixes of all linters, or a list of linter keys (ex: JAVASCRIPT_ES,MARKDOWN_MARKDOWNLINT)

Only for GitHub Action Workflow file if you use it:

• APPLY_FIXES_EVENT: all, push, pull_request, none (use none in case of use of Updated sources reporter)
• APPLY_FIXES_MODE: commit to create a new commit and push it on the same branch, or pull_request to create a new PR targeting the branch.

Apply fixes issues

You may see github permission errors, or workflows not run on the new commit.

To solve these issues, you can apply one of the following solutions.

• Method 1: The most secured

  • Create Fine Grained Personal Access Token, scoped only on your repository and then copy the PAT value
  • Define environment secret variable named PAT on your repository, and paste the PAT value
  • Update your Github Actions Workflow to add the environment name

• Method 2: Easier, but any contributor with write access can see your Personal Access Token

  • Create Classic Personal Access Token, then copy the PAT value
  • Define secret variable named PAT on your repository, and paste the PAT value

Notes

• You can use Updated sources reporter if you don't want fixes to be automatically applied on git branch, but download them in a zipped file and manually extract them in your project
• If used, APPLY_FIXES_EVENT and APPLY_FIXES_MODE can not be defined in .mega-linter.ymlconfig file, they must be set as environment variables
• If you use APPLY_FIXES, add the following line in your .gitignore file

megalinter-reports/

Linter specific variables

See variables related to a single linter behavior in linters documentations

Pre-commands

MegaLinter can run custom commands before running linters (for example, installing an plugin required by one of the linters you use)

Example in .mega-linter.yml config file

PRE_COMMANDS:
  - command: npm install eslint-plugin-whatever
    cwd: root        # Will be run at the root of MegaLinter docker image
    secured_env: true  # True by default, but if defined to false, no global variable will be hidden (for example if you need GITHUB_TOKEN)
  - command: echo "pre-test command has been called"
    cwd: workspace   # Will be run at the root of the workspace (usually your repository root)
    continue_if_failed: False  # Will stop the process if command is failed (return code > 0)
  - command: pip install flake8-cognitive-complexity
    venv: flake8 # Will be run within flake8 python virtualenv. There is one virtualenv per python-based linter, with the same name
  - command: export MY_OUTPUT_VAR="my output var" && export MY_OUTPUT_VAR2="my output var2"
    output_variables: ["MY_OUTPUT_VAR","MY_OUTPUT_VAR2"] # Will collect the values of output variables and update MegaLinter own ENV context
  - command: echo "Some command called before loading MegaLinter plugins"
    cwd: workspace   # Will be run at the root of the workspace (usually your repository root)
    continue_if_failed: False  # Will stop the process if command is failed (return code > 0)
    tag: before_plugins # Tag indicating that the command will be run before loading plugins

Post-commands

MegaLinter can run custom commands after running linters (for example, running additional tests)

Example in .mega-linter.yml config file

POST_COMMANDS:
  - command: npm run test
    cwd: "workspace"   # Will be run at the root of the workspace (usually your repository root)
    continue_if_failed: False  # Will stop the process if command is failed (return code > 0)

Environment variables security

Secured env variables

MegaLinter runs on a docker image and calls the linters via command line to gather their results.

If you run it from your CI/CD pipelines, the docker image may have access to your environment variables, that can contain secrets defined in CI/CD variables.

As it can be complicated to trust the authors of all the open-source linters, MegaLinter removes variables from the environment used to call linters.

Thanks to this feature, you only need to trust MegaLinter and its internal python dependencies, but there is no need to trust all the linters that are used !

You can add secured variables to the default list using configuration property SECURED_ENV_VARIABLES in .mega-linter.yml or in an environment variable (priority is given to ENV variables above .mega-linter.yml property).

Values can be:

• String (ex: MY_SECRET_VAR)
• Regular Expression (ex: (MY.*VAR))

Environment variables are secured for each command line called (linters, plugins, sarif formatter...) except for PRE_COMMANDS , ONLY if you define secured_env: false in the command.

Secured configuration examples

• Example of adding extra secured variables .mega-linter.yml:

SECURED_ENV_VARIABLES:
  - MY_SECRET_TOKEN
  - ANOTHER_VAR_CONTAINING_SENSITIVE_DATA
  - OX_API_KEY
  - (MY.*VAR)  # Regex format

• Example of adding extra secured variables in CI variables, so they can not be overridden in .mega-linter.yml:

SECURED_ENV_VARIABLES=MY_SECRET_TOKEN,ANOTHER_VAR_CONTAINING_SENSITIVE_DATA,OX_API_KEY

Default secured variables

If you override SECURED_ENV_VARIABLES_DEFAULT, it replaces the default list, so it's better to only define SECURED_ENV_VARIABLES to add them to the default list !

SECURED_ENV_VARIABLES_DEFAULT contains:

• GITHUB_TOKEN
• PAT
• SYSTEM_ACCESSTOKEN
• GIT_AUTHORIZATION_BEARER
• CI_JOB_TOKEN
• GITLAB_ACCESS_TOKEN_MEGALINTER
• GITLAB_CUSTOM_CERTIFICATE
• WEBHOOK_REPORTER_BEARER_TOKEN
• NODE_TOKEN
• NPM_TOKEN
• DOCKER_USERNAME
• DOCKER_PASSWORD
• CODECOV_TOKEN
• GCR_USERNAME
• GCR_PASSWORD
• SMTP_PASSWORD
• CI_SFDX_HARDIS_GITLAB_TOKEN
• (SFDX_CLIENT_ID_.*)
• (SFDX_CLIENT_KEY_.*)

Unhide variables for linters

You can configure exceptions for a specific linter by defining (linter-key)_UNSECURED_ENV_VARIABLES.

Variable names in this list won't be hidden to the linter commands.

TERRAFORM_TFLINT_UNSECURED_ENV_VARIABLES:
  - GITHUB_TOKEN # Can contain string only, not regex

CLI lint mode

Each linter is pre-configured to use a default lint mode, which are visible in the MegaLinter documentation (example). The possible values are:

• list_of_files: The linter is called only once, and passed a list of all the files to be processed
• project: The linter is called only once, from the root folder of the repository, and it scans for the files to process, as no file names are provided it
• file: The linter is called once per file, which hurts performance

You can override the CLI_LINT_MODE by using a configuration variable for each linter (see linters documentation).

• Linters that default to the file lint mode cannot be overridden to use the list_of_files lint mode
• Linters that default to the project lint mode cannot be overridden to use either the list_of_files or file lint modes.

Allowing file or list_of_files to be overridden to project is mostly for workarounds. For example, some linters have a problem finding their config file when the current folder isn't the repository's root folder.

Special considerations:

• Linters that are configured to use the project lint mode ignore variables like FILTER_REGEX_INCLUDE and FILTER_REGEX_EXCLUDE, as they are not passed a list of files to lint. For those linters, you must check their documentation to see if a linter can be configured to ignore specific files. For example, the Secretlint linter ignore files listed in ~/.secretlintignore by default, or it can be configured to instead ignore files listed in ~/.gitignore by setting REPOSITORY_SECRETLINT_ARGUMENTS to --secretlintignore .gitignore..

Reporters

MegaLinter can generate various reports that you can activate / deactivate and customize

Flavors

To improve run performances, we generate Flavored MegaLinter images containing only the list of linters related to a project type

• When using default MegaLinter, if a MegaLinter Flavor would cover all your project requirements, a message is added in the logs
• If your project uses a MegaLinter Flavor not covering linter requirements, an error message will be thrown with instructions about how to solve the issue

The following table doesn't display docker pulls from MegaLinter v4 & v5 images.

	Flavor	Description	Embedded linters	Info
	all	Default MegaLinter Flavor	124
	c_cpp	Optimized for pure C/C++ projects	54
	ci_light	Optimized for CI items (Dockerfile, Jenkinsfile, JSON/YAML schemas,XML	21
	cupcake	MegaLinter for the most commonly used languages	83
	documentation	MegaLinter for documentation projects	49
	dotnet	Optimized for C, C++, C# or VB based projects	61
	dotnetweb	Optimized for C, C++, C# or VB based projects with JS/TS	70
	formatters	Contains only formatters	17
	go	Optimized for GO based projects	51
	java	Optimized for JAVA based projects	52
	javascript	Optimized for JAVASCRIPT or TYPESCRIPT based projects	59
	php	Optimized for PHP based projects	54
	python	Optimized for PYTHON based projects	62
	ruby	Optimized for RUBY based projects	50
	rust	Optimized for RUST based projects	50
	salesforce	Optimized for Salesforce based projects	54
	security	Optimized for security	24
	swift	Optimized for SWIFT based projects	50
	terraform	Optimized for TERRAFORM based projects	54

If you need a new flavor, post an issue 😉

Badge

You can show MegaLinter status with a badge in your repository README

If your main branch is master , replace main by master in URLs

Markdown

• Format

[![MegaLinter](https://github.com/<OWNER>/<REPOSITORY>/workflows/MegaLinter/badge.svg?branch=main)](https://github.com/<OWNER>/<REPOSITORY>/actions?query=workflow%3AMegaLinter+branch%3Amain)

• Example

[![MegaLinter](https://github.com/nvuillam/npm-groovy-lint/workflows/MegaLinter/badge.svg?branch=main)](https://github.com/nvuillam/npm-groovy-lint/actions?query=workflow%3AMegaLinter+branch%3Amain)

reStructuredText

• Format

.. |MegaLinter yes| image:: https://github.com/<OWNER>/<REPOSITORY>/workflows/MegaLinter/badge.svg?branch=main
   :target: https://github.com/<OWNER>/<REPOSITORY>/actions?query=workflow%3AMegaLinter+branch%3Amain

• Example

.. |MegaLinter yes| image:: https://github.com/nvuillam/npm-groovy-lint/workflows/MegaLinter/badge.svg?branch=main
   :target: https://github.com/nvuillam/npm-groovy-lint/actions?query=workflow%3AMegaLinter+branch%3Amain

Note: IF you did not use MegaLinter as GitHub Action name, please read GitHub Actions Badges documentation{target=_blank}

Plugins

For performances and security reasons, we can not embed all linters of the world within MegaLinter.

But our core architecture allows to build and publish MegaLinter Plugins !

External Plugins Catalog

Note: Using an external plugin means you trust its author

Submit a Pull Request if you want your plugin to appear here :)

Use external plugins

Add plugin URLs in PLUGINS property of .mega-linter.yml. URLs must either begin with "https://" or take the form of "file://<path>", where <path> points to a valid plugin descriptor file.

Note: Both <path> and the default mount directory (/tmp/lint/<path>) will be checked for a valid descriptor.

Example

PLUGINS:
  - https://raw.githubusercontent.com/kpj/jupyfmt/master/mega-linter-plugin-jupyfmt/jupyfmt.megalinter-descriptor.yml
  - file://.automation/test/mega-linter-plugin-test/test.megalinter-descriptor.yml

Create your own plugin

You can implement your own descriptors and load them as plugins during MegaLinter runtime

• Descriptor format is exactly the same than MegaLinter embedded ones (see json schema documentation)
• Plugins descriptor files must be named **.megalinter-descriptor.yml and respect MegaLinter Json Schema
• Plugins must be hosted in a url containing **/mega-linter-plugin-**/
• File URLs must conform to the same directory and file naming criteria as defined above.

Limitations

• For now, the only install attributes managed are dockerfile instructions starting by RUN

They talk about MegaLinter

English articles

French articles

Japanese articles

Videos

• How to: Secrets scanning, by Hackitect's playground

• How to use MegaLinter with Jenkins, by Darin Pope / Cloudbees

• (FR) MegaLinter presentation at DevCon 20 / Programmez Magazine, by Nicolas Vuillamy

• Code quality - Ep01 - MegaLinter, one linter to rule them all, by Bertrand Thomas

• DevSecOps Webinar using MegaLinter, by 5.15 Technologies{target=_blank}

• Ortelius Architecture Meeting, with a review of MegaLinter, by Steve Taylor{target=_blank} from Ortelius

• (FR) Coding Tech - L'importance de la CI/CD dans le dveloppement de logiciels, by Arsene Fougerouse from R2DevOps

Web Sites

• analysis-tools.dev{target=_blank}
• awesome-linters{target=_blank}
• schemastore.org{target=_blank}
• r2devops.io{target=_blank}
• abhith.net{target=_blank}

• my-devops-lab.com{target=_blank}

Linters

• checkstyle{target=_blank}
• clj-kondo{target=_blank}
• cljstyle{target=_blank}
• cspell{target=_blank}
• detekt{target=_blank}
• djlint{target=_blank}
• dotenv-linter{target=_blank}
• editorconfig-checker{target=_blank}
• eslint{target=_blank}
• eslint-plugin-jsonc{target=_blank}
• hadolint{target=_blank}
• htmlhint{target=_blank}
• jscpd{target=_blank}
• kics{target=_blank}
• ktlint{target=_blank}
• lintr{target=_blank}
• markdown-link-check{target=_blank}
• npm-groovy-lint{target=_blank}
• npm-package-json-lint{target=_blank}
• pmd{target=_blank}
• rst-lint{target=_blank}
• rstcheck{target=_blank}
• rubocop{target=_blank}
• scalafix{target=_blank}
• secretlint{target=_blank}

Frequently Asked Questions

My repo CI already have linters and they're perfectly working, so why do I need MegaLinter ?

You can perfectly continue using your installed linters and deactivate them in .mega-linter.yml. For example, in a javascript project using eslint, you can configure MegaLinter with DISABLE: JAVASCRIPT. That way, you will benefit from both your installed linters but also from other MegaLinter linters checking JSON, YAML, Markdown, Dockerfile, Bash, spelling mistakes, dead URLs

Ok but how does it work ?

MegaLinter is based on Docker images containing either all linters, or just a selection of linters if you are using a MegaLinter flavor for a project using a specific language / format

The core architecture does the following:

• Initialization
  • List all project files:
    • except files in ignored folders (node_modules, etc)
    • except files not matching FILTER_REGEX_INCLUDE (if defined by user)
    • except files matching FILTER_REGEX_EXCLUDE (if defined by user)
  • Collect files for each activated linter, matching their own filtering criteria:
    • file extensions
    • file names
    • file content
    • <descriptor_or_linter_key>_FILTER_REGEX_INCLUDE (if defined by user)
    • <descriptor_or_linter_key>_FILTER_REGEX_EXCLUDE (if defined by user)
• Linting
  • Parallelly, for each linter with matching files:
    • Call the linter on matching files (or the whole project for some linters like copy-paste detector)
    • Call activated linter-level reporters (GitHub Status Reporter)
• Finalization
  • Call activated global level reporters (GitHub Pull Request Comment Reporter, File.io Reporter, Email Reporter)
  • Manage return code:
    • 0 if no error (or only non blocking errors if user defined DISABLE_ERRORS or <descriptor_or_linter_key>_DISABLE_ERRORS)
    • 1 if errors

How to contribute

Contributions to MegaLinter are very welcome, the more we're, the stronger MegaLinter is ! Please follow Contributing Guide

To help, you can also:

• ⭐ star the repository
• 🍺 offer a beer !
• report problems and request new features
• share on twitter{target=_blank}

Special thanks

Maintainers

MegaLinter wouldn't be what it is without its great team of maintainers !

• Kurt Von Laven
• Borja Dominguez
• Edouard Choiniere
• Nicolas Vuillamy (Creator)

Contributors

Open-source teams

MegaLinter obviously would not exist without its linters and libraries, so many thanks to all the dedicated Open-Source teams maintaining all these awesome linters !

Super-Linter team

MegaLinter has been built on the ashes of a rejected Pull Request{target=_blank} on GitHub Super-Linter{target=_blank}.

Even if I disagree with their decision to remain in bash, the core team has always been nice and supporting during the time I was a Super-Linter contributor{target=_blank} :)

License

• GNU Affero General Public License

MegaLinter vs Super-Linter

The hard-fork of Super-Linter to be rewritten in Python isn't just a language switch: use of python flexibility and libraries allowed to define lots of additional functions described below

Security

MegaLinter hides many environment variables when calling the linters.

That way you need to trust only MegaLinter core code with your secrets, not the 100+ embedded linters !

Performances

• MegaLinter Flavors allow to use smaller docker images, so the pull time is reduced
• Thanks to python multiprocessing capabilities, linters are run in parallel, which is way faster than Super-Linter bash script who runs all linters in sequence
• When the linter allows it, call it 1 time with N files, instead of calling N times with one file

More languages and formats linted

• C, C++, Copy-Paste detection, Credentials, GraphQL, JSON & YAML with JSON schemas, Markdown tables formatting, Puppet, reStructuredText, Rust, Scala, Spell checker, Swift, Visual Basic .NET

Automatically apply formatting and fixes

MegaLinter can automatically apply fixes performed by linters, and push them to the same branch, or create a Pull Request that you can validate

This is pretty handy, especially for linter errors related to formatting (in that case, you don't have any manual update to perform)

Run locally

MegaLinter can be run locally thanks to mega-linter-runner

Reports

Capabilities

• Accuracy: Count the total number of errors and not only the number of files in error
• Show linter version and applied filters for each linter processed
• Reports stored as artefacts on GitHub Action run or other remote files
  • General log
  • One report file by linter

Additional Reporters

• Console

• Text files
• GitHub Pull Request comments

• Gitlab Merge Request comments

• Bitbucket Pull Request comments

• Azure Pull Request comments

• Markdown Summary

• Updated sources
• Email
• File.io

Enhanced Configuration

• Assisted installation and configuration using a yeoman generator and JSON schemas for configuration file

• Configure include and exclude regexes for a single language or linter: ex: JAVASCRIPT_FILTER_REGEX_INCLUDE (src)
• Configure additional CLI arguments for a linter: ex: JAVASCRIPT_ES_ARGUMENTS "--debug --env-info"
• Configure non blocking errors for a single language or linter: ex: JAVASCRIPT_DISABLE_ERRORS
• Simplify languages and linters variables
  • ENABLE = list of languages and formats to apply lint on codebase (default: all)
  • ENABLE_LINTERS = list of linters to apply lint on codebase (default: all)
  • DISABLE = list of languages and formats to skip (default: none)
  • DISABLE_LINTERS = list of linters to skip (default: none)
  • Variables VALIDATE_XXX are still taken in account (but should not be used in association with ENABLE and DISABLE variables)

Enhanced Documentation

• HTML documentation

• One page per linter documentation :
  • All variables that can be used with this linter
  • List of file extensions, names and filters applied by the linter
  • Link to MegaLinter default linter configuration
  • Link to linter Web-Site
  • Link to official page explaining how to customize the linter rules
  • Link to official page explaining how to disable rules from source comments
  • Examples of linter command line calls behind the hood
  • Help command text
  • Installation commands

• Installation links for related IDEs

• README
  • Separate languages, formats and tooling formats in the linters table
  • Add logos for each descriptor

Plugins management

For linters less commonly used, MegaLinters offers a plugins architecture so anyone can publish plugins

Simplify architecture and evolutive maintenance

• Refactoring runtime in Python, for easier handling than bash thanks to classes and python modules
• Everything related to each linter in a single descriptor YML file
  • easier evolutive maintenance
  • less conflicts to manage between PRs.
  • Few special cases require a python linter class)
• Default behaviours for all linters, with possibility to override part of them for special cases
• Hierarchical architecture: Apply fixes and new behaviours to all linters with a single code update
• Documentation as code
  • Generate linters tables (ordered by type: language, format & tooling format) and include it in README. (see result)
  • Generate one markdown file per Linter, containing all configuration variables, infos and examples (See examples)
• Automatic generation of Dockerfile using YML descriptors, always using the linter latest version
  • Dockerfile commands (FROM, ARG, ENV, COPY, RUN )
  • APK packages (linux)
  • NPM packages (node)
  • PIP packages (python)
  • GEM packages (ruby)
  • Phive packages (PHP)
• Have a centralized exclude list (node_modules,.rbenv, etc)

Improve robustness & stability

• Test classes for each capability
• Test classes for each linter: Automatic generation of test classes using .automation/build.py
• Setup code coverage
• Development CD / CI
  • Validate multi-status on PR inside each PR (posted from step "Run against all code base")
  • Run test classes and code coverage with pytest during validation GitHub Action
  • Validate descriptor YML files with json schema during build
  • Automated job to upgrade linters to their latest stable version