[Moin-user] Configuring URL prefix for Moin served via Nginx + Gunicorn

[Darren Spruell]

On Tue, May 27, 2014 at 11:17 AM, Paul Boddie <paul at boddie.org.uk> wrote:
> On Tuesday 27. May 2014 09.27.29 Darren Spruell wrote:
>> Greetings,
>>
>> MoinMoin 1.9.7
>> Gunicorn 18.0
>> Nginx 1.4.1
>>
>> I have a single wiki instance that works correctly when served from
>> the root of my site (/). I want to migrate it on the site now to be
>> served from /wiki/home/ (e.g.
>> http://www.example.org/wiki/home/HelpContents). When I configure this
>> on Nginx and then set 'url_prefix_static' in the MoinMoin config, wiki
>> pages are not served correctly. i.e. attempting to access
>> http://www.example.org/wiki/home/ attempts to load a page named
>> 'wiki/home' and MoinMoin returns 404 with "This page does not exist
>> yet. You can create a new empty page, or use one of the page
>> templates."
>
> So you first need to make sure that Moin is served for that resource and not
> the root resource, and you then need to let Moin know that it is rooted at
> this new resource itself.

Sounds so simple! :)

>> I cannot find a config option to instruct MoinMoin that it is being
>> served from a subdirectory of the site and to therefore operate under
>> a URL prefix. I understand that 'url_prefix_static' is only for static
>> media. I notice that
>> http://moinmo.in/HelpOnConfiguration#Configuration_of_multiple_wikis
>> documents a config option 'url_prefix' however various references make
>> it look as if that setting is no longer used/suggested.
>
> Yes, there's a mention of it in wikiconfig.py files that I've seen, but it
> appears to be obsolete.

As it turns out, my attempting to find an option like this (configure
the wiki software to know what path it is served from) is a habit
formed from using various other software including at least one wiki
engine which uses a setting like this:

$wgScriptPath       = "/wiki/work";

I guess what I missed is that it's not necessarily MoinMoin that needs
to be told this, but the WSGI server hosting MoinMoin?

>> Gunicorn is a WSGI server but as opposed to uwsgi it uses standard
>> HTTP as a service protocol; I think this prevents one from passing
>> environment settings (such as SCRIPT_NAME) as one would for e.g. FCGI
>> or UWSGI, etc. However I notice that placing the following in my
>> moin.wsgi seems to fix he path finding:
>>
>> os.environ['SCRIPT_NAME'] = '/wiki/home'
>
> Well, this should be presented to Moin by the Web server: that's what it is
> for! However, in moin.wsgi, you might be able to set the fix_script_name
> setting instead.

Was curious about this, did not see this setting in the installed
moin.wsgi but did find it in the FCGI driver script.

>> To me, this seems like more of a hack than a solution.
>>
>> Current config details:
>>
>> # Nginx config section
>> location /wiki/home {
>>     try_files           $uri @wiki_home_rewrite;
>> }
>> location @wiki_home_rewrite {
>>     proxy_set_header    X-Forwarded-For $proxy_add_x_forwarded_for;
>>     proxy_set_header    Host $http_host;
>>     proxy_redirect      off;
>>     proxy_pass          http://127.0.0.1:8001;
>> }
>>
>> # wikiconfig.py
>> class Config(multiconfig.DefaultConfig):
>>     ...
>>     url_prefix_static = '/wiki/home' + url_prefix_static
>>     ...
>>
>> Is there a way to configure MoinMoin to understand that it is being
>> served from a URL with a prefix path and operate as desired without
>> modifying the environment in the WSGI driver script?
>
> If you can get away with fix_script_name, then yes. Otherwise, perhaps not.
> Again, without things like SCRIPT_NAME, scripts know nothing about their
> environment or the way they are deployed.

And I guess this was the key. Stumbled into this FAQ entry:

http://gunicorn-docs.readthedocs.org/en/latest/faq.html#how-do-i-set-script-name

The resulting configuration in Nginx's configuration that works for me:

location /wiki/home {
    try_files           $uri @wiki_home_rewrite;
}
location @wiki_home_rewrite {
    proxy_set_header    X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header    Host $http_host;
    proxy_set_header    SCRIPT_NAME /wiki/home;
    proxy_redirect      off;
    proxy_pass          http://127.0.0.1:8001;
}

Having SCRIPT_NAME sent literally as a request header is
...interesting, but seems to be what Gunicorn is expecting (if not set
as an env var).

Will add a blurb at http://moinmo.in/HowTo - anything else of note about this?

-- 
Darren Spruell
phatbuckett at gmail.com