Is there an easy way to setup a web remote with a URL to an existing annex such as the following?
git annex initremote my_annex type=web URL=http://my_server.net/path/to/annex
I've created an annex mirror using an rsync special remote on a web server. I can browse the files via HTTP, but how do I tell git annex to fetch the files from there?
The web special remote is not the thing you want to use for this. That represents arbitrary files on any website, not a single git-annex repository on one website.
Just add a git remote using the http protocol, pointing to a git repository.
See setup a public repository on a web site for several configurations you will probably want to set on that repository to make it work well over http.
There is not currently a way to access files that were stored in a rsync special remote over http instead of rsync. That would need a new special remote, distinct from the web special remote.
I suppose it's a reasonable request, since the rsync and directory special remotes are already cross compatible. And it could probably also be used for anonymous access to webdav and S3 special remotes.
Anyway, the option that is available today, and works, is to mirror a git repository to the web server (running
git update-server-infofirst) and add a git remote with the http url.