html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,issue,performed_via_github_app
https://github.com/simonw/datasette/issues/838#issuecomment-643083451,https://api.github.com/repos/simonw/datasette/issues/838,643083451,MDEyOklzc3VlQ29tbWVudDY0MzA4MzQ1MQ==,79913,2020-06-12T06:04:14Z,2020-06-12T06:04:14Z,NONE,"Hmm, I haven't tried removing `ProxyPassReverse`, but it doesn't touch the HTML, which is the issue I'm seeing. You can read the [documentation here](https://httpd.apache.org/docs/2.4/mod/mod_proxy.html#proxypassreverse). `ProxyPassReverse` is a standard directive when proxying with Apache. I've used it dozens of times with other applications.

Looking a little more at the code, I think the issue here is that the behaviour of `base_url` makes sense when Datasette is _mounted_ at a path within a larger application, but not when HTTP requests are being _proxied_ to it.

In a _mount_ situation, it is perfectly fine to construct URLs reusing the domain and path from the request. In a _proxy_ situation, it never is, as the domain and path in the request are not the domain and path that the non-proxy client actually needs to use. That is, links which include the Apache → Datasette request origin, `localhost:8001`, instead of the browser → Apache request origin, `example.com`, will be broken.

The tests you pointed to also reflect this in two ways:

1. They strip a leading `http://localhost`, allowing such URLs in the facet links to pass, but inclusion of that in a proxy situation would mean the URL is broken.

2. The test client emits direct ASGI events instead of actual proxied HTTP requests. The headers of these ASGI events don't reflect the way an HTTP proxy works; instead they pass through the original request path which contains `base_url`. This works because Datasette responds to requests equivalently at either `/…` or `/{base_url}/…`, which makes some sense in a _mount_ situation but is unconventional (albeit workable) for a proxied app.

Apps that support being proxied automatically support being mounted, but apps that only support being mounted don't automatically support being proxied.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",637395097,