fix(v2): use absolute path to manifest file

[lex111]

Motivation

If you visit any page other than the home page, for example https://v2.docusaurus.io/docs/, then you can see the following error in the console:

Failed to load resource: the server responded with a status of 404 () manifest.json

Or something like this:

Manifest: Line: 1, column: 1, Syntax error.

Have you read the Contributing Guidelines on pull requests?

Yes

Test Plan

Preview (see motivation section).

Related PRs

(If this PR adds or changes functionality, please take some time to update the docs at https://github.com/facebook/docusaurus, and link to your PR here.)

[docusaurus-bot]

Deploy preview for docusaurus-2 ready!

Built with commit 1f39ece

https://deploy-preview-3554--docusaurus-2.netlify.app

[slorber]

Hmmm that's annoying 😅

I tried to keep relative paths because I wanted the PWA to work in deploy previews, using baseurl. Seems it does not work on the deploy preview now :'( maybe we should just prepend manually the baseurl in the config ?

[lex111]

I don't get what you mean. Right now the browser cannot find the manifest file because a relative URL is specified.

[slorber]

I mean, we want the (+) icon to be there in all cases

Currently, it only works on the homepage (which is the problem your PR fixes, as it will work from /docs/ too)

But your PR breaks the (+) on deploy previews: https://deploy-preview-3554--docusaurus-2.netlify.app/classic/

While it used to work on PRs. (but only on homepage 🤪 ): https://deploy-preview-3558--docusaurus-2.netlify.app/classic/

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The ideal solution should make it work:

• for all subpaths: / or /docs/myDoc
• for deploy previews: /classic/ or /classic/docs/myDoc

This way it's easier to review PWA issues in deploy previews

[lex111]

Aha, I figured it out now, so I changed to use baseUrl const, it should be OK, I guess.

[slorber]

LGTM, we'll see if main site still works after :D