Secretlint

Secretlint is that Pluggable linting tool to prevent committing credentials.

Features

• Scanner: Found credentials in a project and report these
• Project Friendly: Easy to set up your project and integrate CI services
• Pre-Commit Hook: Prevent committing credential files
• Pluggable: Allow creating custom rule and flexible configuration
• Documentation: Describe the reason that rule detect it as secret

Quick Demo

You can view secretlint linting result on https://secretlint.github.io/.

Quick Start

You can try to use Secretlint on your project at one command.

If you already have installed Docker:

docker run -v `pwd`:`pwd` -w `pwd` --rm -it secretlint/secretlint secretlint "**/*"

If you already have installed Node.js:

npx @secretlint/quick-start "**/*"

After running, If you got empty result and exit status is 0, your project is secure. Otherwise, you got some error report, your project includes credential as raw data.

You want to get continuous security, Please see following installation guide and setup pre-commit hook and CI.

Installation

Using Docker

Prerequisites: Require Docker

Use our Docker container to get an environment with Node.js and secretlint and running as fast as you can download them.

You can check all files under the current directory with secretlint by following command:

docker run -v `pwd`:`pwd` -w `pwd` --rm -it secretlint/secretlint secretlint "**/*"

secretlint/secretlint docker container work without configuration by design.

This Docker Image has built-in packages:

• @secretlint/secretlint-rule-preset-recommend
• @secretlint/secretlint-rule-pattern
• @secretlint/secretlint-formatter-sarif

For more details, please see secretlint's Dockerfile.

Using Node.js

Prerequisites: Require Node.js 20+.

Secretlint is written by JavaScript. You can install Secretlint using npm:

npm install secretlint @secretlint/secretlint-rule-preset-recommend --save-dev

You should then set up a configuration file:

npx secretlint --init

Finally, you can run Secretlint on any file or directory like this:

npx secretlint "**/*"

:memo: Secretlint support glob pattern and glob pattern should be wrapped by a double quote.

It is also possible to install Secretlint globally using npm install --global. But, We do not recommended it, some rules may be broken in globally.

Using Single-Executable Binary

Prerequisites: None

You can use secretlint command without Node.js by using a single-executable binary.

1. Download the latest binary from Releases page
2. Change the file permission to executable: chmod +x ./secretlint
3. Run ./secretlint --init to create a configuration file
4. Run ./secretlint "**/*" to lint your project

For more details, please see publish/binary-compiler README.

Usage

secretlint --help show Usage.

Secretlint CLI that scan secret/credential data.

Usage
$ secretlint [file|glob*]

Note
supported glob syntax is based on microglob
https://github.com/micromatch/micromatch#matching-features

Options
--init             setup config file. Create .secretlintrc.json file from your package.json
--format           [String] formatter name. Default: "stylish". Available Formatter: checkstyle, compact, jslint-xml, junit, pretty-error, stylish, tap, unix, json, mask-result, table
--output           [path:String] output file path that is written of reported result.
--no-color         disable ANSI-color of output.
--no-terminalLink  disable terminalLink of output.
--no-maskSecrets   disable masking of secret values; secrets are masked by default.
--secretlintrc     [path:String] path to .secretlintrc config file. Default: .secretlintrc.*
--secretlintignore [path:String] path to .secretlintignore file. Default: .secretlintignore
--stdinFileName    [String] filename to process STDIN content. Some rules depend on filename to check content.

Options for Developer
--profile          Enable performance profile.
--secretlintrcJSON [String] a JSON string of .secretlintrc. use JSON string instead of rc file.

Experimental Options
--locale            [String] locale tag for translating message. Default: en

Examples
$ secretlint ./README.md
# glob pattern should be wrapped with double quote
$ secretlint "**/*"
$ secretlint "source/**/*.ini"
# output masked result to file
$ secretlint .zsh_history --format=mask-result --output=.zsh_history
# lint STDIN content instead of file
$ echo "SECRET CONTENT" | secretlint --stdinFileName=secret.txt

Exit Status
Secretlint exits with the following values:

    - 0:
      - Linting succeeded, no errors found.
      - Found lint error but --output is specified.
    - 1:
      - Linting failed, errors found.
    - 2:
      - Unexpected error occurred, fatal error.

Configuration

Secretlint has a configuration file .secretlintrc.{json,yml,js}.

• Document: Configuring Secretlint

After running secretlint --init, you'll have a .secretlintrc.json file in your directory.

In it, you'll see some rules configured like this:

1{
2  "rules": [
3    {
4      "id": "@secretlint/secretlint-rule-preset-recommend"
5    }
6  ]
7}

The id property is the name of secretlint rule package.

Secretlint does not have built-in rule. You want to add some rule and You should install the package and add the rule to .secretlintrc file.

Each rule has same configuration pattern:

• options: Option definition for the rule. For more details, see each rule documentation
• disabled: If disabled is true, disable the rule
• allowMessageIds: allowMessageIds is an array of message id that you want to suppress error report
  • message id is defined in each rule and please see the rule documentation

Example: options

For example, @secretlint/secretlint-rule-example has allows in options. This allows option define a list of RegExp-like String that you want to ignore.

1{
2  "rules": [
3    {
4      "id": "@secretlint/secretlint-rule-example",
5      "options": {
6        "allows": [
7          "/dummy_secret/i"
8        ]
9      }
10    }
11  ]
12}

When you use a preset like @secretlint/secretlint-rule-preset-recommend, you need to put the option in rules.

For example, an option for @secretlint/secretlint-rule-preset-recommend > @secretlint/secretlint-rule-aws

1{
2  "rules": [
3    {
4      "id": "@secretlint/secretlint-rule-preset-recommend",
5      "rules": [
6        {
7          "id": "@secretlint/secretlint-rule-aws",
8            "options": {
9              "allows": [
10	            // it will be ignored
11                "xxxx-xxxx-xxxx-xxxx-xxxx"
12              ]
13            }
14        }
15      ]
16    }
17  ]
18}

Example: allowMessageIds

For example, you have got following error report by run secretlint:

$ secretlint "**/*"

SECRET.txt
  1:8  error  [EXAMPLE_MESSAGE] found secret: SECRET  @secretlint/secretlint-rule-example

✖ 1 problem (1 error, 0 warnings)

This error's message id is EXAMPLE_MESSAGE in @secretlint/secretlint-rule-example.

If you want to ignore this error, please use allowMessageIds.

1{
2  "rules": [
3    {
4      "id": "@secretlint/secretlint-rule-example",
5      "allowMessageIds": ["EXAMPLE_MESSAGE"]
6    }
7  ]
8}

When you use a preset like @secretlint/secretlint-rule-preset-recommend, you need to put the option in rules.

For example, If you want to ignore "AWSAccountID" and "AWSAccessKeyID" of "@secretlint/secretlint-rule-aws", you can write following.

1{
2  "rules": [
3    {
4      "id": "@secretlint/secretlint-rule-preset-recommend",
5      "rules": [
6        {
7          "id": "@secretlint/secretlint-rule-aws",
8          "allowMessageIds": ["AWSAccountID", "AWSAccessKeyID"]
9        }
10      ]
11    }
12  ]
13}

Ignoring by comment

@secretlint/secretlint-rule-filter-comments supports ignoring comment like secretlint-disable.

// secretlint-disable

THIS IS SECRET, BUT IT WILL BE IGNORED

// secretlint-enable

For more details, please see Configuring Secretlint.

Use Cases

Mask secrets in lint error message (Default behavior)

Secretlint masks secrets in lint error messages by default. This is useful to prevent accidental secret exposure in CI logs, terminal output, or when using AI agent tools.

1# Secrets are masked by default
2$ secretlint "**/*"

To show actual secret values in the output, use --no-maskSecrets:

1$ secretlint --no-maskSecrets "**/*"

Fix secrets

Secretlint can not fix the secrets automatically. However, It is useful that --format=mask-result mask the secrets of input file.

For example, you can mask the secrets of .zsh_history file and overwrite it.

1$ secretlint .zsh_history --format=mask-result --output=.zsh_history

Rule Packages

Secretlint rules has been implemented as separated modules.

• @secretlint/secretlint-rule-npm
• @secretlint/secretlint-rule-aws
• @secretlint/secretlint-rule-gcp
• @secretlint/secretlint-rule-github
• @secretlint/secretlint-rule-privatekey
• @secretlint/secretlint-rule-basicauth
• @secretlint/secretlint-rule-slack
• @secretlint/secretlint-rule-sendgrid
• @secretlint/secretlint-rule-shopify
• @secretlint/secretlint-rule-openai
• @secretlint/secretlint-rule-linear
• @secretlint/secretlint-rule-secp256k1-privatekey
• @secretlint/secretlint-rule-no-k8s-kind-secret
• @secretlint/secretlint-rule-pattern
• @secretlint/secretlint-rule-no-homedir
• @secretlint/secretlint-rule-no-dotenv

Also, Secretlint provide rule preset that includes recommended rule set.

• @secretlint/secretlint-rule-preset-recommend
  • Recommended rule set

Custom Rules

You can create own secretlint rule.

You want to get a secretlint rule for suitable your project and you can create it! A secretlint rule is a just npm package.

If you want to know creating secretlint rule, please see docs/secretlint-rule.md.

Integrations

Pre-commit Hook per project

You can use Secretlint with some pre-commit tool. This can prevent to commit secret data by linting with Secretlint.

Applying secretlint to the project and improve security on team developing.

Husky + lint-staged

Use Case: If you want to introduce secretlint to Node.js project, this combination is useful.

Install Husky and lint-staged:

npx husky-init && npm install lint-staged --save-dev

Add hooks to .husky/pre-commit:

npx husky add .husky/pre-commit "npx --no-install lint-staged"

Edit package.json:

1{
2  // add "lint-staged" field
3  "lint-staged": {
4    "*": [
5      "secretlint"
6    ]
7  }
8}

This means that check each staged file by Secretlint before commit.

pre-commit

Use Case: You have a project that is developing with Docker. Easy to integrate to secretlint.

Install pre-commit

# macOS. see also https://pre-commit.com/#install
brew install pre-commit

Create .pre-commit-config.yaml:

-   repo: local
    hooks:
    -   id: secretlint
        name: secretlint
        language: docker_image
        entry: secretlint/secretlint:latest secretlint

Example setup repository:

• https://github.com/azu/secretlint-pre-commit-example

Bash Script

Alternately you can save this script as .git/hooks/pre-commit and give it execute permission(chmod +x .git/hooks/pre-commit):

1#!/bin/sh
2FILES=$(git diff --cached --name-only --diff-filter=ACMR | sed 's| |\\ |g')
3[ -z "$FILES" ] && exit 0
4
5# Secretlint all selected files
6echo "$FILES" | xargs ./node_modules/.bin/secretlint
7# If you using docker
8# echo "$FILES" | xargs docker run -v `pwd`:`pwd` -w `pwd` --rm secretlint/secretlint secretlint
9RET=$?
10if [ $RET -eq 0 ] ;then
11    exit 0
12else
13    exit 1
14fi

Pre-commit Hook globally

Use Case: If you want to check any project by secretlint, you can use global git hooks.

Git 2.9+ supports core.hooksPath. It allow to integrate secretlint globally.

We have created example git hooks project using secretlint + Docker.

• secretlint/git-hooks
  • Requirement: Docker

You can set up by following steps:

1# clone this repository
2git clone https://github.com/secretlint/git-hooks git-hooks
3cd git-hooks
4# integrate secretlint to git hook globally
5git config --global core.hooksPath $(pwd)/hooks

After setup of core.hooksPath, secretlint check any file before you commit it.

For more details, see secretlint/git-hooks project.

Node.js version also can be used for global git hook. If you interesting in it, please see @azu/git-hooks.

CI

GitHub Actions

If you already set secretlint Using Node.js, you can run secretlint with your configuration on GitHub Actions.

Put .github/workflows/secretlint.yml in your repository.

1name: Secretlint
2on: [push, pull_request]
3permissions:
4  contents: read
5jobs:
6  test:
7    name: "Secretlint"
8    runs-on: ubuntu-latest
9    steps:
10      - name: checkout
11        uses: actions/checkout@v3
12      - name: setup Node.js
13        uses: actions/setup-node@v3
14        with:
15          node-version: 20
16      - name: Install
17        run: npm ci
18      - name: Lint with Secretlint
19        run: npx secretlint "**/*"

This configuration also integrate Pull Request review comment via actions/setup-node.

• Example Repository: https://github.com/secretlint/secretlint-github-actions-example
• Example Pull Request: https://github.com/secretlint/secretlint-github-actions-example/pull/1/files

If you want to only check diff files, please see following example:

1name: test-diff
2on:
3  push:
4  pull_request:
5jobs:
6  test-diff:
7    permissions:
8      contents: read
9    name: "Run secretlint to diff files"
10    runs-on: ubuntu-latest
11    steps:
12      - name: checkout
13        uses: actions/checkout@v4
14        with:
15          # fetch history to get all changed files on push or pull_request event
16          fetch-depth: 0
17      - name: Get changed files
18        id: changed-files
19        uses: tj-actions/changed-files@v44
20      - name: setup Node ${{ matrix.node-version }}
21        uses: actions/setup-node@v4
22        with:
23          node-version: 20
24      - name: Show changed files
25        run: echo "${{ steps.changed-files.outputs.all_changed_files }}"
26      - name: Install
27        if: steps.changed-files.outputs.any_changed == 'true'
28        run: npm ci
29      - name: Run secretlint
30        if: steps.changed-files.outputs.any_changed == 'true'
31        run: npx secretlint ${{ steps.changed-files.outputs.all_changed_files }}

Mega-Linter

Mega-Linter is a linters aggregator natively compliant with any CI tool, embedding 80+ linting apps, including secretlint by default.

You can install it on any repository project using the following command (Node.js must be installed previously)

1npx mega-linter-runner --install

Browser

Secretlint WebExtension works on your browser.

• Firefox: https://addons.mozilla.org/ja/firefox/addon/secretlint/
• Chrome: https://chrome.google.com/webstore/detail/secretlint/hidpojbnemkajlnibhmeilpgoddkjjkf

This web extension aim to founds credentials that are included in your request/response.

Secretlint WebExtension integrate to DevTools in Chrome/Firefox. This extension help web developer to notice exposed credential.

Others

SARIF format support

Please use @secretlint/secretlint-formatter-sarif.

npm install @secretlint/secretlint-formatter-sarif --dev
secretlint --format @secretlint/secretlint-formatter-sarif "**/*"

Semantic Versioning Policy

Secretlint project follow Semantic Versioning(secretlint-rule-preset-canary is exception).

• Patch release (intended to not break your lint build)
  • A bug fix to the CLI or core (including formatters).
  • Improvements to documentation.
  • Non-user-facing changes such as refactoring.
  • Re-releasing after a failed release (i.e., publishing a release that doesn't work for anyone).
• Minor release (might break your lint build)
  • A new option.
  • An existing rule is deprecated.
  • A new CLI capability is created.
  • New public API are added (new classes, new methods, new arguments to existing methods, etc.).
    • It might break TypeScript definitions
  • A new formatter is created.
• Major release (break your lint build)
  • A new option to an existing rule that results in secretlint reporting more errors by default.
  • An existing formatter is removed.
  • Add new default rule to rule preset.
  • Part of the public API is removed or changed in an incompatible way.

Motivation

• git-secrets is useful, but it is hard to setup per project.
  • It main use-case is globally installation
  • Secretlint want to install for a project and customize setting per project.
• repo-security-scanner, Gitleaks and truffleHog is good scan tools
  • Secretlint need to flexible customize that include ignoring definitions, custom rules.
• detect-secrets is similar tools, but it adopts opt-out approach
  • Secretlint adopts opt-in approach
  • We also need to custom rules by user
    • See Bring-your own-plugins (BYOP), via --custom-plugins option by KevinHock · Pull Request #255 · Yelp/detect-secrets
• GitHub support secret scanning, but it only works after commit push
  • Secretlint works on your local machine, Secretlint can prevent to commit

Philosophy

• Reduce false-positive of linting
• Integration to developing workflow
• Empower Users to Contribute

Opt-in instead of Opt-out

Secretlint adopt opt-in approach.

In our experience, linting tools that report various errors by default is difficult to use. Opt-in approach help to introduce Secretlint increasing.

It will help to reduce false-positive by configuration.

Rule as Documentation

We think a rule as a documentation. So, Each rule should have reasonable documentation.

We need to describe why this file is error. A rule that has not documentation, It is just a opinionated.

Describe the reason of error and then it will lead to reduce false-positive error.

Also, Secretlint CLI support hyperlink in Terminal. It means that you can jump to rule documentation from lint error message directly.

Example on iTerm 2: Cmd + Click error's messageId and open AWSSecretAccessKey on your browser.

If you want to know support terminal, please see Hyperlinks in Terminal Emulators.

Also, Welcome to Contribution about secretlint documentation!

Why Node.js?

• Package Manager
  • Require package manager to realize flexible pluggable system
  • Node.js has npm and yarn as package manager
  • Package manager help to install custom plugin/rule by user
• Exist Reference Implementation
  • Node.js already has pluggable linting tools like ESLint, textlint, stylelint etc
  • So Node.js user familiar with pluggable linting tools
  • Previously, I created textlint as same approach, so I familiar with Node.js
• Users
  • JavaScript is Popular language
  • It means that empower Users to Contribute
  • Users can create own rule by own hand

Of course, secretlint also support Docker.

Changelog

See Releases page.

Contributing

Pull requests and stars are always welcome.

For bugs and feature requests, please create an issue.

See also, CONTRIBUTING.md and CODE_OF_CONDUCT.md

Add New Rule

You can use npm run gen:rule command to create new rule.

1npm run gen:rule

For more details, please see CONTRIBUTING.md

Benchmark

Benchmark workflow is run on every commit.

• Benchmark: https://secretlint.github.io/secretlint/dev/bench/

Author

• github/azu
• twitter/azu_re

License

MIT © azu