Add --spa-index option

[sinking-point]

Closes #474

[aliemjay]

Good job!
This would be even easier to implement with actix/actix-web#2135

Now I wonder if --spa-index and --index options should be compatible or if there is any use case for both of them together?
If not, then I think it is better to have a --spa flag instead of --spa-index. In this way, we avoid conflicting command line options. So then the usage would be something like:
$ miniserve --spa --index ./index.html

[sinking-point]

Thanks. I'm aware of the PR, but those changes aren't yet released and I needed this feature sooner rather than later.

Hmm, your suggestion is certainly more intuitive. But if you want to have an SPA that is not at the root of your site then having the flexibility of my implementation would be useful.

[sinking-point]

That is something of an edge case though. I can change it to be how you suggested if you like.

[aliemjay]

Well, I don't have a strong opinion on this because I don't use SPAs!

I think we need a second opinion @svenstaro .

[svenstaro]

Is the behavior of the current --index as you would expect for your needs, @sinking-point? There were a ton of changes to miniserve behavior recently and this might just be fixed for your use case now.

[sinking-point]

@svenstaro I have just tried with the latest version and unless I'm missing something the problem is the same. Is there a specific change that you expected to resolve this?

[svenstaro]

@sinking-point can you fix the CI thing real quick? It's just a small formatting issue.

[sinking-point]

@svenstaro sure, should be fine now.

[svenstaro]

Clippy doesn't seem happy yet. :)

[svenstaro]

@sinking-point Can you fix this real quick?

[sinking-point]

@svenstaro my bad, I didn't realise there was a linter to contend with. Hopefully sorted now.

[svenstaro]

Cool, merging as is but I'll likely make some more ergonomics changes.

[sinking-point]

Perfect, thanks for merging.