Algolia support from config only

[chalin]

• Closes Algolia search support via config only? #991
• Adds a configurable default implementation of Algolia DocSearch support
• Allows multiple search options to be chosen, but warns about it
• Updates the Search docs
• Empties layouts/partials/hooks/head-end.html and layouts/partials/hooks/body-end.html from the skeletal Algolia-support code.

Preview: https://deploy-preview-1662--docsydocs.netlify.app/docs/adding-content/search/#algolia-docsearch

[!IMPORTANT]
I've temporarily disabled GSE so that reviewers can preview Algolia DocSearch. I'll remove that change before we merge.
(It has been removed.)

[deining]

Should we better place this in head-css.html?

[deining]

Since minimum required version is hugo v0.110 now, what about fetching the docsearch npm resource at build time rather than at runtime? This way, we also have better GDPR support (#1354).
Also, I amended the code so that users now can specify the wanted docsearch version inside thier project's hugo.yaml:

params:
  search:
    algolia:
      version: 3.5.1

Suggested change

	{{ if and .Site.Params.search (isset .Site.Params.search "algolia") -}}
	{{ if and .Site.Params.search (isset .Site.Params.search "algolia") -}}
	{{ $version := "v3.5.1" -}}
	{{ with .Site.Params.search.algolia.version -}}
	{{ $version = . -}}
	{{ end -}}
	{{ $cdnurl := printf "https://cdn.jsdelivr.net/npm/@docsearch/css@%s" $version -}}
	{{ if eq (resources.GetRemote $cdnurl) nil -}}
	{{ errorf "Invalid Algolia version %s, could not retrieve this version from CDN" $version -}}
	{{ end -}}
	{{ with resources.GetRemote $cdnurl -}}
	{{ with .Err -}}
	{{ errorf "Error while retrieving resource %q from CDN. Status: %s." $cdnurl .Data.Status -}}
	{{ else -}}
	{{ $secureCSS := . | resources.Fingerprint "sha512" -}}
	<link rel="stylesheet" href="{{ .RelPermalink }}" integrity="{{ $secureCSS.Data.Integrity }}" crossorigin="anonymous" />
	{{ end -}}
	{{ end -}}
	{{ end -}}

[deining]

Same as for css: why not retrieving the .js resource at build time?

Suggested change

	{{ define "algolia/scripts" }}
	{{ define "algolia/scripts" }}
	{{ $version := "v3.5.1" -}}
	{{ with .Site.Params.search.algolia.version -}}
	{{ $version = . -}}
	{{ end -}}
	{{ $cdnurl := printf "https://cdn.jsdelivr.net/npm/@docsearch/js@%s" $version -}}
	{{ if eq (resources.GetRemote $cdnurl) nil -}}
	{{ errorf "Invalid Algolia version %s, could not retrieve this version from CDN" $version -}}
	{{ end -}}
	{{ with resources.GetRemote $cdnurl -}}
	{{ with .Err -}}
	{{ errorf "Error while retrieving resource %q from CDN. Status: %s." $cdnurl .Data.Status -}}
	{{ else -}}
	{{ $secureJS := . | resources.Fingerprint "sha512" -}}
	<script src="{{ .RelPermalink }}" integrity="{{ $secureJS.Data.Integrity }}"
	crossorigin="anonymous" ></script>
	{{ end -}}
	{{ end -}}

[chalin]

Thanks for your valuable feedback @deining. I've updated the UG as you suggested.

Great idea to fetch dependencies at build time. It should be used uniformly for all 3rd-party features! But for now, I would rather keep this PR simple and consistent with Docy's current way of supporting 3rd-party features/services. There is a plan to eventually address GDPR requirements, and better (modular) handling of 3rd-party dependencies. I'd rather keep that separate.

As for using head-css.html: it is (currently) used for a different purpose, and this PR isn't setting a precedent by modifying head.html directly -- Prism CSS is handled in head.html too.

So I'd leave the rest of this PR as is for now.

[deining]

Thanks for your valuable feedback @deining.

You are welcome.

I've updated the UG as you suggested.

Great!

Great idea to fetch dependencies at build time. It should be used uniformly for all 3rd-party features! But for now, I would rather keep this PR simple and consistent with Docy's current way of supporting 3rd-party features/services. There is a plan to eventually address GDPR requirements, and better (modular) handling of 3rd-party dependencies. I'd rather keep that separate.

As for using head-css.html: it is (currently) used for a different purpose, and this PR isn't setting a precedent by modifying head.html directly -- Prism CSS is handled in head.html too.

So I'd leave the rest of this PR as is for now.

Agreed. I have more Algolia related improvements in the pipeline, let's get this merged first!

[chalin]

Thanks, awaiting your approval @deining.

[deining]

LGTM.