lychee link checking action

Quickly check links in Markdown, HTML, and text files using lychee.

When used in conjunction with Create Issue From File, issues will be created when the action finds link problems.

Usage

Here is a full example of a GitHub workflow file:

It will check all repository links once per day and create an issue in case of errors. Save this under .github/workflows/links.yml:

name: Links

on:
  repository_dispatch:
  workflow_dispatch:
  schedule:
    - cron: "00 18 * * *"

jobs:
  linkChecker:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Link Checker
        id: lychee
        uses: lycheeverse/[email protected]
        env:
          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}

      - name: Create Issue From File
        if: steps.lychee.outputs.exit_code != 0
        uses: peter-evans/create-issue-from-file@v3
        with:
          title: Link Checker Report
          content-filepath: ./lychee/out.md
          labels: report, automated issue

Alternative approach:

This will check all repository links during any git push event and for all pull requests. If there's an error, it will fail the action. This has the benefit of ensuring that during a Pull Request, no link is added that is broken and any existing link will be caught if they become broken. Save this under .github/workflows/links-fail-fast.yml:

name: Links (Fail Fast)

on:
  push:
  pull_request:

jobs:
  linkChecker:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Link Checker
        uses: lycheeverse/[email protected]
        with:
          fail: true
        env:
          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}

Passing arguments

This action uses lychee for link checking. lychee arguments can be passed to the action via the args parameter. On top of that, some other inputs are supported: format, output, and fail.

- name: Link Checker
  uses: lycheeverse/[email protected]
  with:
    # Check all markdown and html files in repo (default)
    args: --verbose --no-progress './**/*.md' './**/*.html'
    # Use json as output format (instead of markdown)
    format: json
    # Use different output filename
    output: /tmp/foo.txt
    # Fail action on broken links
    fail: true

See lychee's documentation for all possible arguments.

Excluding links from getting checked

Add a .lycheeignore file to the root of your repository to exclude links from getting checked. It supports regular expressions. One expression per line.

Optional environment variables

Issues with links will be written to a file containing the error report. The default path is lychee/out.md. The path and filename may be overridden with the following variable:

• LYCHEE_OUT - The path to the output file for the Markdown error report

Fancy badge

Pro tip: You can add a little badge to your repo to show the status of your links. Just replace org with your organisation name and repo with the repository name and put it into your README.md:

[![Check Links](https://github.com/org/repo/actions/workflows/links.yml/badge.svg)](https://github.com/org/repo/actions/workflows/links.yml)

It will look like this:

Troubleshooting and common problems

See lychee's Troubleshooting Guide for solutions to common link-checking problems.

Performance

A full CI run to scan 576 links takes approximately 1 minute for the analysis-tools-dev/static-analysis repository.

Security and Updates

It is recommended to pin lychee-action to a fixed version for security reasons. You can use dependabot to automatically keep your Github actions up-to-date. This is a great way to pin lychee-action, while still receiving updates in the future. It's a relatively easy thing to do.

Create a file named .github/dependabot.yml with the following contents:

version: 2
updates:
  - package-ecosystem: "github-actions"
    directory: ".github/workflows"
    schedule:
      interval: "daily"

When you add or update the dependabot.yml file, this triggers an immediate check for version updates. Please see the documentation for all configuration options.

Security tip

For additional security when relying on automation to update actions you can pin the action to a SHA-256 rather than the semver version so as to avoid tag spoofing Dependabot will still be able to automatically update this.

For example:

- name: Link Checker
  uses: lycheeverse/lychee-action@cb79c9607b37671965f8dbb54cae47795758a440 #1.1.1
  #...

Credits

This action is based on peter-evans/link-checker and uses lychee (written in Rust) instead of liche (written in Go) for link checking. For a comparison of both tools, check out this comparison table.

License

lychee is licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)

at your option.