IAlloc.hs 5.27 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
                  -> JSObject JSValue
                  -> 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
  let running = "running"
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  return $ (n, Instance.create n mem disk running 0 0)
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-- | Parses an instance as found in the cluster instance list.
parseInstance :: NameAssoc        -- ^ The node name-to-index association list
              -> String           -- ^ The name of the instance
              -> JSObject 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
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    nodes <- fromObj "nodes" a
    pnode <- readEitherString $ head nodes
    pidx <- lookupNode ktn n pnode
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    let snodes = tail nodes
    sidx <- (if null snodes then return Node.noSecondary
             else (readEitherString $ head snodes) >>= lookupNode ktn n)
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    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
          -> JSObject JSValue -- ^ The JSON object
          -> Result (String, Node.Node)
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parseNode n a = do
    let name = n
    offline <- fromObj "offline" a
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    drained <- fromObj "drained" a
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    node <- (case offline of
               True -> return $ Node.create name 0 0 0 0 0 True
               _ -> 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
                 return $ Node.create n mtotal mnode mfree
                        dtotal dfree (offline || drained))
    return (name, 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
  let obj = decoded
  -- request parser
  request <- fromObj "request" obj
  rname <- fromObj "name" request
  -- existing node parsing
  nlist <- fromObj "nodes" obj
  let ndata = fromJSObject nlist
  nobj <- (mapM (\(x,y) -> asJSObject y >>= parseNode x)) ndata
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  let (ktn, nl) = assignIndices nobj
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  -- existing instance parsing
  ilist <- fromObj "instances" obj
  let idata = fromJSObject ilist
  iobj <- (mapM (\(x,y) -> asJSObject y >>= parseInstance ktn x)) idata
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  let (kti, il) = assignIndices iobj
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  (map_n, map_i, csf) <- mergeData (nl, il)
  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 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]