add link checking

[afeld]

https://trello.com/c/BPLKQCPk/137-set-up-link-verification

This pull request adds (internal) link verification to the built gitbook site using HTML Proofer.

Now that I've gone through the (surprising) trouble of getting this working, though, I'm wondering if we should be catching these issues in cg-compliance via Travis. That way, the links don't get broken before they are merged. Hmmmm...

/cc @ctro @DavidEBest @geramirez @LinuxBozo (FYI you don't seem to be watching this repository)

[DavidEBest]

@afeld. cg-compliance doesn't build the gitbook, does it? I like the idea of moving the error as close to the source as possible, but how difficult would it be to do it in cg-compliance directly?

[LinuxBozo]

@afeld @DavidEBest Doesn't the Compliance Masonry CLI build the gitbook from the yml? Shouldn't the link verification be added there?

[ctro]

It does seem to make more sense to do this in cg-compliance with travis at build-time, rather than here at deploy-time. But that means getting the compliance-masonry binary up there & actually building the gitbook on travis... at that point may as well do the deploy from Travis too? ;)

[afeld]

Doesn't the Compliance Masonry CLI build the gitbook from the yml?

No, that just assembles the Markdown from the YAML—the gitbook CLI is what actually builds the site.

Shouldn't the link verification be added there?

Perhaps...I was just looking for the modification that could be done the quickest.

It does seem to make more sense to do this in cg-compliance with travis at build-time

Yeeeeah, though that would mean Travis would be running Python, Go, Node, and Ruby 😆 😐 Will see what it would take to make that happen.

at that point may as well do the deploy from Travis too?

🤷

[ctro]

Not sure those changes are all worth it. I mean, this works :)

[geramirez]

@afeld yeah, maybe checking links in cg-compliance would be better, could you check external links only?

[afeld]

Others, thoughts about what to do with this?

[DavidEBest]

It is one step removed from the actual code, but checked links is better than unchecked links.

[afeld]

While Slack notifications are turned off, I think having deployments fail for things like this does more harm than good. Closing for now.