[Koha-devel] Plack Middleware to isolate library branches via path

[dcook at prosentient.com.au]

Hi Thomas,

The timing of your email is interesting! I was just reflecting the other day
about how Koha can't work off anything but the root path. 

However, it's not something that I'm likely to ever work on, as the
subdomains work fine for us. (Although self-checkout URLs using branch-based
paths could be very useful for us.)

I have a Catalyst app where I use the out of the box method $c->uri_for
which constructs an absolute URI using the application root (e.g. /aaa/),
but that would require rewriting Koha's templates. I use that same strategy
for some of my other web apps, which lets the deployment be quite flexible.
(In the case of Catalyst, it auto-detects the path based on the location of
the controller. With CGI apps I have, I rely on a configuration variable.)

With your solution, how do you handle Javascript navigation that doesn't
necessarily rely on HTML? (I can't think of any examples off the top of my
head but I'm sure they must exist, although perhaps only on the Staff
Interface...)

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: Tuesday, 19 April 2022 10:13 PM
To: koha-devel at lists.koha-community.org
Subject: [Koha-devel] Plack Middleware to isolate library branches via path

Hi!

A customer wants to access branches/branchgroups via a subpath, instead of
the more common / documented way of setting up a subdomain per
branch:
https://wiki.koha-community.org/wiki/Override_sysprefs_in_Apache_config

So instead of https://aaa.library.example.com/ they want
https://library.example.com/aaa/  (for ~10 branches)


This boils down to:
- matching the path and munging the URL
- setting some ENV vars (OPAC_SEARCH_LIMIT, OPAC_CSS_OVERRIDE, etc)
- munging the HTML generated by Koha to fix the links

While this could be implemented via carefull application of various 
Apache modules (mod_proxy, mod_rewrite, mod_proxy_html) I feel more 
comfortable implementing this in Perl in a Plack Middleware.
The result is not very pretty, but seems to work (see attached code...)

But to load the middleware, I have to enable it in /etc/koha/plack.psgi 
and thus change a core file (or copy upstream plack.psgi and edit the 
copy, which still means that we'll have to apply our changes after each 
update)

In theory we could add some config to load custom Middlewares, but as 
the load order of Middlewares is very relevant, this seems hardly doable 
- unless we start with one middleware config slot at the location I need :-)

Anyway, I think we'll just go with maintaining a custom plack.psgi, 
unless anybody here has any other ideas / best practices / solutions on 
how to mount library branches at location/sub-dirs... I'm also not sure 
if this feature is on any roadmap etc.


Greetings,
domm


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