Markdown link check has an issue with some links even though they work fine

[lbussell]

I have noticed that the markdown link check Github action has issues with certain links, even though the links work correctly.

• https://support.microsoft.com/contactus/ - failing build
• https://mcr.microsoft.com/product/dotnet/nightly/monitor/about - failing build

Both of the links Work On My Machine. This has been causing many valid PRs to appear as failing validation. I believe that retries have caused some of these to pass but I cannot confirm that.

Related: #5818
/cc @MichaelSimons

[lbussell]

[Triage] There are configuration options that we could use here:

1. Only enable Markdown checking on files that are modified in a PR
   • If so, then run against all files separately on a schedule
2. Increase the number of automatic retries, or retry on more/different error codes
3. Allow-list certain links to prevent them from being checked if we know they work (e.g. https://support.microsoft.com/contactus/)

[MichaelSimons]

Another issue I just noticed is 429s when validating the Docker Hub links 😞.

[lbussell]

Another issue I just noticed is 429s when validating the Docker Hub links 😞.

[Triage] Instead of the GitHub READMEs pointing to DockerHub repos, we should make them point to the other GitHub READMEs instead. Since there's no extra content on DH that isn't in our GH readmes, there's not much point in linking there from here. That would remove this entire class of issues.

[lbussell]

[Triage] The original issue described in the post was resolved with #5892, so this can be closed. Any additional work should be filed as a separate issue.

[lbussell]

I found several more instances of this, all on microsoft.com links:

https://learn.microsoft.com/powershell/scripting/install/installing-powershell-on-linux

ERROR: 1 dead links found!
[✖] https://learn.microsoft.com/powershell/scripting/install/installing-powershell-on-linux → Status: 0

https://docs.microsoft.com/virtualization/windowscontainers/images-eula

ERROR: 1 dead links found!
[✖] https://docs.microsoft.com/virtualization/windowscontainers/images-eula → Status: 0

https://learn.microsoft.com/dotnet/core/deploying/ready-to-run

ERROR: 1 dead links found!
[✖] https://learn.microsoft.com/dotnet/core/deploying/ready-to-run → Status: 0

https://learn.microsoft.com/dotnet/api/system.security.cryptography.x509certificates.storelocation

ERROR: 1 dead links found!
[✖] https://learn.microsoft.com/dotnet/api/system.security.cryptography.x509certificates.storelocation → Status: 0

The author of the markdown link checker recommends their new project, UmbrellaDocs/action-linkspector, instead. Development has stopped on the current markdown link checker (source). Of note, the new checker does support running as a Docker image.