IAlloc.hs 5.36 KB
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{-| Implementation of the iallocator interface.

-}

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{-

Copyright (C) 2009 Google Inc.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.

-}

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module Ganeti.HTools.IAlloc
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    ( parseData
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    , formatResponse
    ) where

import Data.Either ()
import Control.Monad
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import Text.JSON (JSObject, JSValue(JSBool, JSString, JSArray),
                  makeObj, encodeStrict, decodeStrict,
                  fromJSObject, toJSString)
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import qualified Ganeti.HTools.Container as Container
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import qualified Ganeti.HTools.Node as Node
import qualified Ganeti.HTools.Instance as Instance
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import Ganeti.HTools.Loader
import Ganeti.HTools.Utils
import Ganeti.HTools.Types
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-- | Parse the basic specifications of an instance.
--
-- Instances in the cluster instance list and the instance in an
-- 'Allocate' request share some common properties, which are read by
-- this function.
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parseBaseInstance :: String
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                  -> [(String, JSValue)]
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                  -> Result (String, Instance.Instance)
parseBaseInstance n a = do
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  disk <- fromObj "disk_space_total" a
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  mem <- fromObj "memory" a
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  vcpus <- fromObj "vcpus" a
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  let running = "running"
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  return (n, Instance.create n mem disk vcpus running 0 0)
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-- | Parses an instance as found in the cluster instance listg.
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parseInstance :: NameAssoc        -- ^ The node name-to-index association list
              -> String           -- ^ The name of the instance
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              -> [(String, JSValue)] -- ^ The JSON object
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              -> Result (String, Instance.Instance)
parseInstance ktn n a = do
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  base <- parseBaseInstance n a
  nodes <- fromObj "nodes" a
  pnode <- readEitherString $ head nodes
  pidx <- lookupNode ktn n pnode
  let snodes = tail nodes
  sidx <- (if null snodes then return Node.noSecondary
           else readEitherString (head snodes) >>= lookupNode ktn n)
  return (n, Instance.setBoth (snd base) pidx sidx)
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-- | Parses a node as found in the cluster node list.
parseNode :: String           -- ^ The node's name
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          -> [(String, JSValue)] -- ^ The JSON object
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          -> Result (String, Node.Node)
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parseNode n a = do
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  offline <- fromObj "offline" a
  drained <- fromObj "drained" a
  node <- (if offline || drained
           then return $ Node.create n 0 0 0 0 0 0 True
           else do
             mtotal <- fromObj "total_memory" a
             mnode  <- fromObj "reserved_memory" a
             mfree  <- fromObj "free_memory"  a
             dtotal <- fromObj "total_disk"   a
             dfree  <- fromObj "free_disk"    a
             ctotal <- fromObj "total_cpus"   a
             return $ Node.create n mtotal mnode mfree
                    dtotal dfree ctotal False)
  return (n, node)
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-- | Top-level parser.
parseData :: String         -- ^ The JSON message as received from Ganeti
          -> Result Request -- ^ A (possible valid) request
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parseData body = do
  decoded <- fromJResult $ decodeStrict body
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  let obj = fromJSObject decoded
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  -- request parser
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  request <- liftM fromJSObject (fromObj "request" obj)
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  rname <- fromObj "name" request
  -- existing node parsing
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  nlist <- liftM fromJSObject (fromObj "nodes" obj)
  nobj <- mapM (\(x,y) -> asJSObject y >>= parseNode x . fromJSObject) nlist
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  let (ktn, nl) = assignIndices nobj
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  -- existing instance parsing
  ilist <- fromObj "instances" obj
  let idata = fromJSObject ilist
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  iobj <- mapM (\(x,y) ->
                    asJSObject y >>= parseInstance ktn x . fromJSObject) idata
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  let (kti, il) = assignIndices iobj
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  (map_n, map_i, csf) <- mergeData [] (nl, il)
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  req_nodes <- fromObj "required_nodes" request
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  optype <- fromObj "type" request
  rqtype <-
      case optype of
        "allocate" ->
            do
              inew <- parseBaseInstance rname request
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              let io = snd inew
              return $ Allocate io req_nodes
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        "relocate" ->
            do
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              ridx <- lookupInstance kti rname
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              ex_nodes <- fromObj "relocate_from" request
              let ex_nodes' = map (stripSuffix $ length csf) ex_nodes
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              ex_idex <- mapM (Container.findByName map_n) ex_nodes'
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              return $ Relocate ridx req_nodes (map Node.idx ex_idex)
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        other -> fail ("Invalid request type '" ++ other ++ "'")
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  return $ Request rqtype map_n map_i csf
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-- | Formats the response into a valid IAllocator response message.
formatResponse :: Bool     -- ^ Whether the request was successful
               -> String   -- ^ Information text
               -> [String] -- ^ The list of chosen nodes
               -> String   -- ^ The JSON-formatted message
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formatResponse success info nodes =
    let
        e_success = ("success", JSBool success)
        e_info = ("info", JSString . toJSString $ info)
        e_nodes = ("nodes", JSArray $ map (JSString . toJSString) nodes)
    in encodeStrict $ makeObj [e_success, e_info, e_nodes]