[tahoe-dev] [tahoe-lafs] #648: show server capacities on introducer welcome page

[tahoe-lafs]

#648: show server capacities on introducer welcome page
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 Reporter:  zooko        |           Owner:  somebody 
     Type:  enhancement  |          Status:  new      
 Priority:  major        |       Milestone:  undecided
Component:  code         |         Version:  1.3.0    
 Keywords:               |   Launchpad_bug:           
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Comment(by warner):

 Yeah! I've been thinking of two approaches:

  * add methods to the existing storage server remote API to query for
 total-space, space-available, etc (basically all the storage-related
 things you can get from the current stats gatherer). Have the introducer
 (or anyone else who's interested) query this interface and aggregate the
 results.
  * add a new service class (to the one "storage" one that we have now),
 with a separate remote API, that just does space-available information.
 Publish this through the introducer. Have the introducer (or anyone else
 who's interested) query this interface and aggregate the results.

 The first approach feels a bit weird because it would conflate server
 access (upload/download shares) with a purely informational interface, and
 getting access to one should not necessarily provide access to the other.
 The second approach feels cleaner, but I've been holding off on
 implementing it until #466 is done (signed/extensible introducer messages,
 which is blocked on ECDSA). It doesn't strictly require #466, though..
 maybe we could build it first.

 Another approach would be to use the extensible-message part of #466 and
 publish space-available information in each announcement, but this would
 never be updated/updateable as quickly as having a remotely-callable query
 interface.

 In any case, the information could be used by either the introducer, or by
 a separate disk-watcher process, not unlike the one we have right now. The
 existing disk-watcher queries the HTTP-based stats interface on each node
 to construct total-available, total-left, and rate-of-space-usage
 averages. One annoying aspect of this HTTP-based approach is that it must
 be configured manually: each time you add a server, you have to add its
 /statistics URL to the list. A process which used the introducer
 announcements to locate storage servers to query would be a lot easier to
 use.

-- 
Ticket URL: <http://allmydata.org/trac/tahoe/ticket/648#comment:1>
tahoe-lafs <http://allmydata.org>
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