Cherrypy VirtualHost dispatcher not working - cherrypy

Question

I've got the following in my cherrypy config, but /foo is not handling my request to http://foo.bar.com ... The cherrypy app is behind nginx which is passing the host header through - I'm outputting the Host header at / and it is returning 'foo.bar.com' so I'd expect /foo to handle this request.
[/]
request.dispatch = cherrypy.dispatch.VirtualHost(**{
'foo.bar.com': '/foo',
})
Nginx is doing a proxy_pass to 127.0.0.1 with:
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

Answer 1

I don't understand the problem, but it seems to be an application vs global config problem. I was setting the VirtualHosts in server.cfg which was loaded into the global config and I was mounting without an application config:
cherrypy.config.update("server.cfg")
cherrypy.tree.mount(root, "/")
Setting the application config fixed the problem:
conf = {
"/": {
"request.dispatch": cherrypy.dispatch.VirtualHost(
**{
"foo.domain.com:8000": "/foo",
"bar.domain.com:8000": "/bar"
}
)
}
}
cherrypy.tree.mount(root, "/", conf)
If anyone wants to explain I'll accept their answer. I'm now wondering if any setting I put under [/] in server.cfg (cherrypy.config) will work correctly or if all path specific config needs to be in the application config.

Answer 2

You can't set the dispatcher from the global config, I do think that this is not obvious but the dispatcher itself is responsible of handling the merging of the configurations.
Another reason for confusion is that because if you use the cherryd command it might seem like is something normal.
For example you could deploy an application like this:
cherryd -c server.cfg
Having server.cfg as:
[global]
tree.app = myapp.root
[/]
request.dispatch = cherrypy.dispatch.MethodDispatcher()
With the following implementation on myapp.py:
import cherrypy
class Root(object):
exposed = True
def GET(self):
return "Hi!"
root = cherrypy.Application(Root())
But cherryd have a few trick under his wing.
One is the added namespace "tree" on which you set tree.NAME_OF_APP = INSTANCE_OF_CHERRYPY_APP and more importantly setting the dispatcher on the "global" configuration file works because the cherryd command merges the configuration file into the application when there is only one application mounted on the tree.
Something like:
cherrypy.tree.apps.values()[0].merge(config)
Effectively making the "global" configuration like a "local-per-app" configuration.