On Tue, Apr 11, 2017 at 12:17 PM, Ricardo Dias <rdias@xxxxxxxx> wrote: > Hi, > > What if ceph-mgr modules could actually depend on each other. That way, > we could have a single cherrypy module and other modules could depend > on the cherrypy module. > The cherrypy module would redirect requests to the corresponding module. > Would that be an option? That's already possible, it's just that the cherrypy module wouldn't be a mgr module per se, it would just be a python module that the mgr modules used. John > I know nothing about the ceph-mgr architecture, so ignore my suggestion if > does not make sense at all. > > Ricardo Dias > >> On 11 Apr 2017, at 11:41, Tim Serong <tserong@xxxxxxxx> wrote: >> >> Hi All, >> >> We have a problem using cherrypy in mgr modules. Specifically, multiple >> modules that use cherrypy stomp on each other. I discovered this while >> playing with John's guilolz experiment >> (https://github.com/ceph/ceph/pull/13725). >> >> Both rest and guilolz modules follow this pattern: >> >> cherrypy.config.update({'server.socket_port': ....}) >> cherrypy.tree.graft(...) # or cherrypy.tree.mount(...) >> cherrypy.engine.start() >> cherrypy.engine.block() >> >> So: >> >> - They're both first setting the port to listen on globally. >> - They both eat the whole web namespace (graft/mount). >> - They both call cherrypy.engine.start() to start the server. >> >> In each of the above cases, the first module loaded will win and the >> other won't (or, it might be racey and you'll kinda get a mix?). For >> example, the second call to cherrypy.engine.start() fails complaining it >> can't be called more than once from the same thread. >> >> I'm not sure how best to deal with this. Assuming we *do* want it to be >> possible for multiple modules that provide a web service to be loaded >> simultaneously, we need to: >> >> - not set the port globally. >> - not stomp on each others namespaces. >> - only call cherrypy.engine.start() once. >> >> You can have multiple cherrypy servers listening on different ports, so >> that gets us part of the way there, e.g.: >> >> from cherrypy._cpserver import Server >> server = Server() >> server.socket_port = .... # whatever >> server.subscribe() >> >> But, this doesn't fix the namespace eating problem. That might be >> doable with cherrypy virtualhosts >> (http://tools.cherrypy.org/wiki/VirtualHosts), but I haven't >> experimented further with that yet. >> >> Also, those subscribe()s have to happen before the >> cherrypy.engine.start() call or they have no effect. One way to do that >> would be to have some magic cherrypy module which is always loaded last >> to start the engine, but that might be ugly. >> >> Another option might be to have a separate python interpreter per module >> (can't stomp on each other then, right?) but that might be too resource >> intensive. >> >> Thoughts? >> >> Thanks, >> >> Tim >> -- >> Tim Serong >> Senior Clustering Engineer >> SUSE >> tserong@xxxxxxxx >> -- >> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
