[Koha-devel] Serving Intranet from a subpath

[dcook at prosentient.com.au]

I feel like we've had this conversation before but now I can't find a record of it...

I was intrigued by that "base" suggestion, but there's a few issues with it:

1. You've made a mistake regarding relative vs absolute links. The link "/cgi-bin/koha/mainpage.pl" is a relative link with an absolute path reference. So you can use <base href="https://koha-community.org"> to tell the browser to use that base URL to construct an absolute URL. That is, the browser will take you to "https://koha-community.org/cgi-bin/koha/mainpage.pl" with the above. However, it will only ever use the scheme and the server/host. It will ignore any path that you provide. 
2. If you did change all the links from absolute-path to relative-path (ie "cgi-bin/koha/mainpage.pl"), you could use something like <base href="/foo"> but you couldn't use <base href="/foo/koha">. The browser will only use the first path element. I suppose that would get you further than you are now, but it seems inelegant...

Personally, I'm in favour of using "uri_for()" template methods, which are common in pretty much every web framework around today, but it would probably be a prohibitive amount of work. I also wonder how it might affect some of the latest Vue.js work that Jonathan has been doing. 

I'd love to get rid of "/cgi-bin/koha" one day in any case, since it's a holdover from decades past...

Ultimately, I think only the RM can answer this one. 

David Cook
Senior Software Engineer
Prosentient Systems
Suite 7.03
6a Glen St
Milsons Point NSW 2061
Australia

Office: 02 9212 0899
Online: 02 8005 0595

-----Original Message-----
From: Koha-devel <koha-devel-bounces at lists.koha-community.org> On Behalf Of Thomas Klausner
Sent: Friday, 12 August 2022 8:55 PM
To: koha-devel at lists.koha-community.org
Subject: [Koha-devel] Serving Intranet from a subpath

Hi!

(I'm sending this to koha-devel because I guess it's too technical for the general list?)

We are running running the "Intranet" inside an actual intranet (i.e. 
inside a VPN). But this Koha instance is also hosting a related Library whose staff cannot access the VPN. For various reasons it is not possible to mount Koha at it's own domain, so we must make it available at a sub-path (something like "https://www.example.com/foo/koha")

For the OPAC, I already implemented a hacky Plack Middleware that does some rather ugly rewriting or URLs and HTML (ughh..). While we could do the same for Intranet, I first wanted to check if it is maybe already possible to mount it under a subpath, i.e. have an Apache use something like 

ProxyPass /foo/koha/index.html   ...
ProxyPass /foo/koha/cgi-bin/koha ...

Now, while this actually works, the pages returned do not, as all the links they contain point to /cgi-bin/koha (i.e., they loose the mount point and generate bad links).

The usual way to solve this is via something like https://metacpan.org/pod/Plack::Middleware::ReverseProxyPath

But for this work, two things (one small, one not) have to be changed:

* the plack app (i.e. Koha) needs to honor some HTTP Header ENV vars
  (X_FORWARDED_SCRIPT_NAME, X_TRAVERSAL_PATH)
* and all links generated by the app need to also honor those vars.

The usual way for the latter is to *not* generate links by concatenating path fragments or hardcoded them in templates (which seems to be what Koha is doing), but to use a function/method to generate all links (to html pages, static assets and endpoints)

So for example in a template like prog/en/modules/cataloguing/addbooks.tt
we find:
            <a href="/cgi-bin/koha/mainpage.pl">Home</a>

This would need to be changed to 

            <a href=uri_for("/cgi-bin/koha/mainpage.pl")>Home</a>

and uri_for needs to take a look at the ENV and fix the link accordingly.

(The ugly workaround I am using in an OPAC is to use a Middleware to change the HTML after it's generated by Koha but before it is send to the client. shudder...)

So on the one hand this seems to be a small change, but to work it needs to touch ALL templates. (and it will be hard to automatically identify all link-ish text in the templates (href, src, maybe sometimes the url is generated in a template, ...)

Another approach would be to set the mount-point into <base href="/foo/koha"> https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base
But we would still need to change all the links to relative links, as `base` will ignore absolute links, which is what Koha is using now.
though maybe the regex to replace the code is a bit easier
(s{/cgi-bin}{cgi-bin}) as it does have to fiddle with quotes etc.


Our customer is willing to do the work to implement this (probably also in OPAC), but only if the change will be accepted upstream and be usable by the end of this year (i.e. 22.11).

Shall we try to tackle this? Or will this massive change never be accepted? If there is interest, I guess the next step is to open a bug...


Greetings,
domm



-- 
#!/usr/bin/perl                             https://domm.plix.at
for(ref bless{},just'another'perl'hacker){s-:+-$"-g&&print$_.$/}
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