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Comment by nubinetwork | Hacker News Reader

> What was happening instead is that the Prometheus host agent's HTTP server code will give you a HTTP 200 answer (with a generic front page) for any URL except the special URL for its metrics endpoint.

> Neither party is exactly wrong here, but the result is not ideal.

No, Prometheus has a bug if this is the case, and cks says it himself further on...

> all it would need to do is only give a HTTP 200 response for '/' and then a 404 (with the same HTML) for everything else that it answers with the generic front page

View on HN

What might happen is that it's a single page app. So whatever URL you access the same frontend is served. And then the SPA shows the correct content based on the path in the URL. Then it's hard for the backend to know the correct status code to send.

Of course you might still consider that a bug or wrong, but it's reality for a lot of web pages.

I would argue that is still wrong... if the page doesn't exist, you either 404, or 301 to a page that does exist.

That would require you to duplicate all routing between backend and frontend. As long as it's not an API I don't see the need.

> As long as it's not an API I don't see the need.

And I don't see the need to use a SPA almost anywhere. If you are gonna use a SPA for stuff that really doesn't require it, I think it behooves you to still atleast try to conform the the HTTP spec

> And I don't see the need to use a SPA almost anywhere.

Did I advocate for that in any way?

> If you are gonna use a SPA for stuff that really doesn't require it, I think it behooves you to still atleast try to conform the the HTTP spec

Why? Give me a good reason why it's worth the effort for small tools I write.

> Why? Give me a good reason why it's worth the effort for small tools I write

Why are you using SPAs with internal routing for small tools?

An SPA only needs to use urls to represent states that should be externally reachable. If you want those states to be externally reachable, then you probably want those states to be indexable by search engines. You also want users to know if a url is mistyped/miscopied and a 404 response page does a good job of that.

In the end, given the spec, it is on you to carefully consider amd have a good reason to go against the recommendations.

> Why are you using SPAs with internal routing for small tools?

Because I don't use a server if I can help it. Client-side routing is wonderfully easy to use and provides a great user experience. What good does it for me to pre-render the sites or host it on a server where I can route server-side if client-side routing works perfectly for what I write?

> An SPA only needs to use urls to represent states that should be externally reachable.

"Needs" does a lot here. My tools integrate with browser history for navigation, so I need URLs for that as well. But I often make state available in the query, so it's externally reachable.

> If you want those states to be externally reachable, then you probably want those states to be indexable by search engines.

No.

> You also want users to know if a url is mistyped/miscopied and a 404 response page does a good job of that.

I do, and client-side routing gives users a wonderful 404 page. No need for serving a status 404.

> In the end, given the spec, it is on you to carefully consider amd have a good reason to go against the recommendations.

I've given good reasons. You haven't so far.

I see the need for SPA on every site that has internal links and dynamic state of any kind. Seeing a flash is annoying and so is tapping back button only to see the cached version that is not true anymore and forcing a reload. Interop between web pages (and tabs) is practically non-existent. Even right now on HN I’m about to post a comment, and the whole “go back” stack will become irrelevant.

SPA is ironically not needed mostly on single-page sites. When I see comments like this it sincerely puzzles me what your common user stories are and/or how you managed to train a blind eye to all this.

Wouldn’t it be better to auto-extract a list of frontend routes for backend? Our stacks lack the obvious, but instead of fixing them we are searching for good angles.

It depends on your use case. My use case doesn't warrant it.

..or the vuln detection could be less stupid and try to decide whether the content it has retrieved is a bash history or not?

I would agree in principle, but that would require an extensive parser for files it thinks it finds... it's easier to deal with this on the server side than the client side.

No it's not. Dealing with it on the server side means that all tools and servers in the world have to go along with this decision. Posting on a blog saying that people 'SHOULD' do something and actually making it so that this is a reasonable expectation are two very different things.

A vulnerability scanner having to implement hairy heuristics to decide what's a vuln and what's a common false positive is literally its whole job.

There is a standard for HTTP status codes that has dictated what web servers “should” do for quite a while, now. Most web servers respond properly with a 404 “out of the box”, when asked to serve up content that doesn’t exist.

Almost any web server can be configured to provide a generic response to a specific request, for example by ignoring some or all of the url path, and in practice I would bet that a majority of actual instances do this for at least some sets of requests. (To confirm my theory in 20 seconds I checked if https://news.ycombinator.com/user?id=nonexistent_user_1620 returns a 404 or a 200 - it's the latter.)

It's silly to pretend that the use of a 404 in this type of circumstance is either clearcut in the standards or ubiquitous in practice.

> It's silly to pretend that the use of a 404 in this type of circumstance is either clearcut in the standards or ubiquitous in practice.

The standards seem pretty clear to me.

I would point out that technically, the path portion of the HN URI does indeed point to a valid endpoint, it is the query portion of the URI (usually not used by the server to do any routing) that points to a non-existent resource.

Still, HN is wrong here and should be returning a 404 status.

But should != Must.

I think that's still somewhat beside the point though. in the case of Prometheus yes it should return a 404. but what if it was nginx routing all paths to some app? or even just some actual file being served on that path? in either case the vuln scanner says you have an exposed home directory, and that's a false positive.

> Posting on a blog saying that people 'SHOULD' do something

To be fair, it's not about some rando on a blog post. The HTTP response codes and their semantics are in the RFCs. And while it's true the RFCs say SHOULD and not MUST, there are also now ~30 decades of experience and expectation that a non-existent resource is more likely a 404 not 200.

Sure a server can always do what it likes but can't expect it to play well with the outside world if it goes against both convention and documentation.

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