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{-| Implementation of the iallocator interface.

-}

{-

Copyright (C) 2009, 2010, 2011 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.

-}

module Ganeti.HTools.IAlloc

    ( readRequest

    , runIAllocator

    , processRelocate

    ) where

import Data.Either ()

import Data.Maybe (fromMaybe, isJust)

import Data.List

import Control.Monad

import Text.JSON (JSObject, JSValue(JSArray),

                  makeObj, encodeStrict, decodeStrict, fromJSObject, showJSON)

import System (exitWith, ExitCode(..))

import System.IO

import qualified Ganeti.HTools.Cluster as Cluster

import qualified Ganeti.HTools.Container as Container

import qualified Ganeti.HTools.Group as Group

import qualified Ganeti.HTools.Node as Node

import qualified Ganeti.HTools.Instance as Instance

import qualified Ganeti.Constants as C

import Ganeti.HTools.CLI

import Ganeti.HTools.Loader

import Ganeti.HTools.ExtLoader (loadExternalData)

import Ganeti.HTools.Utils

import Ganeti.HTools.Types

-- | Type alias for the result of an IAllocator call.

type IAllocResult = (String, JSValue, Node.List, Instance.List)

-- | 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.

parseBaseInstance :: String

                  -> JSRecord

                  -> Result (String, Instance.Instance)

parseBaseInstance n a = do

  let extract x = tryFromObj ("invalid data for instance '" ++ n ++ "'") a x

  disk  <- extract "disk_space_total"

  mem   <- extract "memory"

  vcpus <- extract "vcpus"

  tags  <- extract "tags"

  dt    <- extract "disk_template"

  let running = "running"

  return (n, Instance.create n mem disk vcpus running tags True 0 0 dt)

-- | 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

              -> JSRecord  -- ^ The JSON object

              -> Result (String, Instance.Instance)

parseInstance ktn n a = do

  base <- parseBaseInstance n a

  nodes <- fromObj a "nodes"

  pnode <- if null nodes

           then Bad $ "empty node list for instance " ++ n

           else 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)

-- | Parses a node as found in the cluster node list.

parseNode :: NameAssoc   -- ^ The group association

          -> String      -- ^ The node's name

          -> JSRecord    -- ^ The JSON object

          -> Result (String, Node.Node)

parseNode ktg n a = do

  let desc = "invalid data for node '" ++ n ++ "'"

      extract x = tryFromObj desc a x

  offline <- extract "offline"

  drained <- extract "drained"

  guuid   <- extract "group"

  vm_capable  <- annotateResult desc $ maybeFromObj a "vm_capable"

  let vm_capable' = fromMaybe True vm_capable

  gidx <- lookupGroup ktg n guuid

  node <- (if offline || drained || not vm_capable'

           then return $ Node.create n 0 0 0 0 0 0 True gidx

           else do

             mtotal <- extract "total_memory"

             mnode  <- extract "reserved_memory"

             mfree  <- extract "free_memory"

             dtotal <- extract "total_disk"

             dfree  <- extract "free_disk"

             ctotal <- extract "total_cpus"

             return $ Node.create n mtotal mnode mfree

                    dtotal dfree ctotal False gidx)

  return (n, node)

-- | Parses a group as found in the cluster group list.

parseGroup :: String     -- ^ The group UUID

           -> JSRecord   -- ^ The JSON object

           -> Result (String, Group.Group)

parseGroup u a = do

  let extract x = tryFromObj ("invalid data for group '" ++ u ++ "'") a x

  name <- extract "name"

  apol <- extract "alloc_policy"

  return (u, Group.create name u apol)

-- | Top-level parser.

--

-- The result is a tuple of eventual warning messages and the parsed

-- request; if parsing the input data fails, we'll return a 'Bad'

-- value.

parseData :: String -- ^ The JSON message as received from Ganeti

          -> Result ([String], Request) -- ^ Result tuple

parseData body = do

  decoded <- fromJResult "Parsing input IAllocator message" (decodeStrict body)

  let obj = fromJSObject decoded

      extrObj x = tryFromObj "invalid iallocator message" obj x

  -- request parser

  request <- liftM fromJSObject (extrObj "request")

  let extrReq x = tryFromObj "invalid request dict" request x

  -- existing group parsing

  glist <- liftM fromJSObject (extrObj "nodegroups")

  gobj <- mapM (\(x, y) -> asJSObject y >>= parseGroup x . fromJSObject) glist

  let (ktg, gl) = assignIndices gobj

  -- existing node parsing

  nlist <- liftM fromJSObject (extrObj "nodes")

  nobj <- mapM (\(x,y) ->

                    asJSObject y >>= parseNode ktg x . fromJSObject) nlist

  let (ktn, nl) = assignIndices nobj

  -- existing instance parsing

  ilist <- extrObj "instances"

  let idata = fromJSObject ilist

  iobj <- mapM (\(x,y) ->

                    asJSObject y >>= parseInstance ktn x . fromJSObject) idata

  let (kti, il) = assignIndices iobj

  -- cluster tags

  ctags <- extrObj "cluster_tags"

  cdata1 <- mergeData [] [] [] [] (ClusterData gl nl il ctags)

  let (msgs, fix_nl) = checkData (cdNodes cdata1) (cdInstances cdata1)

      cdata = cdata1 { cdNodes = fix_nl }

      map_n = cdNodes cdata

      map_i = cdInstances cdata

      map_g = cdGroups cdata

  optype <- extrReq "type"

  rqtype <-

      case () of

        _ | optype == C.iallocatorModeAlloc ->

              do

                rname     <- extrReq "name"

                req_nodes <- extrReq "required_nodes"

                inew      <- parseBaseInstance rname request

                let io = snd inew

                return $ Allocate io req_nodes

          | optype == C.iallocatorModeReloc ->

              do

                rname     <- extrReq "name"

                ridx      <- lookupInstance kti rname

                req_nodes <- extrReq "required_nodes"

                ex_nodes  <- extrReq "relocate_from"

                ex_idex   <- mapM (Container.findByName map_n) ex_nodes

                return $ Relocate ridx req_nodes (map Node.idx ex_idex)

          | optype == C.iallocatorModeChgGroup ->

              do

                rl_names <- extrReq "instances"

                rl_insts <- mapM (liftM Instance.idx .

                                  Container.findByName map_i) rl_names

                gr_uuids <- extrReq "target_groups"

                gr_idxes <- mapM (liftM Group.idx .

                                  Container.findByName map_g) gr_uuids

                return $ ChangeGroup rl_insts gr_idxes

          | optype == C.iallocatorModeNodeEvac ->

              do

                rl_names <- extrReq "instances"

                rl_insts <- mapM (Container.findByName map_i) rl_names

                let rl_idx = map Instance.idx rl_insts

                rl_mode <- extrReq "evac_mode"

                return $ NodeEvacuate rl_idx rl_mode

          | otherwise -> fail ("Invalid request type '" ++ optype ++ "'")

  return (msgs, Request rqtype cdata)

-- | Formats the result into a valid IAllocator response message.

formatResponse :: Bool     -- ^ Whether the request was successful

               -> String   -- ^ Information text

               -> JSValue  -- ^ The JSON encoded result

               -> String   -- ^ The full JSON-formatted message

formatResponse success info result =

    let

        e_success = ("success", showJSON success)

        e_info = ("info", showJSON info)

        e_result = ("result", result)

    in encodeStrict $ makeObj [e_success, e_info, e_result]

-- | Flatten the log of a solution into a string.

describeSolution :: Cluster.AllocSolution -> String

describeSolution = intercalate ", " . Cluster.asLog

-- | Convert allocation/relocation results into the result format.

formatAllocate :: Instance.List -> Cluster.AllocSolution -> Result IAllocResult

formatAllocate il as = do

  let info = describeSolution as

  case Cluster.asSolution as of

    Nothing -> fail info

    Just (nl, inst, nodes, _) ->

        do

          let il' = Container.add (Instance.idx inst) inst il

          return (info, showJSON $ map Node.name nodes, nl, il')

-- | Convert a node-evacuation/change group result.

formatNodeEvac :: Group.List

               -> Node.List

               -> Instance.List

               -> (Node.List, Instance.List, Cluster.EvacSolution)

               -> Result IAllocResult

formatNodeEvac gl nl il (fin_nl, fin_il, es) =

    let iname = Instance.name . flip Container.find il

        nname = Node.name . flip Container.find nl

        gname = Group.name . flip Container.find gl

        fes = map (\(idx, msg) -> (iname idx, msg)) $ Cluster.esFailed es

        mes = map (\(idx, gdx, ndxs) -> (iname idx, gname gdx, map nname ndxs))

              $ Cluster.esMoved es

        failed = length fes

        moved  = length mes

        info = show failed ++ " instances failed to move and " ++ show moved ++

               " were moved successfully"

    in Ok (info, showJSON (mes, fes, Cluster.esOpCodes es), fin_nl, fin_il)

-- | Runs relocate for a single instance.

--

-- This is wrapper over the 'Cluster.tryNodeEvac' function that is run

-- with a single instance (ours), and further it checks that the

-- result it got (in the nodes field) is actually consistent, as

-- tryNodeEvac is designed to output primarily an opcode list, not a

-- node list.

processRelocate :: Group.List      -- ^ The group list

                -> Node.List       -- ^ The node list

                -> Instance.List   -- ^ The instance list

                -> Idx             -- ^ The index of the instance to move

                -> Int             -- ^ The number of nodes required

                -> [Ndx]           -- ^ Nodes which should not be used

                -> Result (Node.List, Instance.List, [Ndx]) -- ^ Solution list

processRelocate gl nl il idx 1 exndx = do

  let orig = Container.find idx il

      sorig = Instance.sNode orig

  when (exndx /= [sorig]) $

       -- FIXME: we can't use the excluded nodes here; the logic is

       -- already _but only partially_ implemented in tryNodeEvac...

       fail $ "Unsupported request: excluded nodes not equal to\

              \ instance's secondary node (" ++ show sorig ++ " versus " ++

              show exndx ++ ")"

  (nl', il', esol) <- Cluster.tryNodeEvac gl nl il ChangeSecondary [idx]

  nodes <- case lookup idx (Cluster.esFailed esol) of

             Just msg -> fail msg

             Nothing ->

                 case lookup idx (map (\(a, _, b) -> (a, b))

                                  (Cluster.esMoved esol)) of

                   Nothing ->

                       fail "Internal error: lost instance idx during move"

                   Just n -> return n

  let inst = Container.find idx il'

      pnode = Instance.pNode inst

      snode = Instance.sNode inst

  when (snode == sorig) $

       fail "Internal error: instance didn't change secondary node?!"

  when (snode == pnode) $

       fail "Internal error: selected primary as new secondary?!"

  nodes' <- if nodes == [pnode, snode]

            then return [snode] -- only the new secondary is needed

            else fail $ "Internal error: inconsistent node list (" ++

                 show nodes ++ ") versus instance nodes (" ++ show pnode ++

                 "," ++ show snode ++ ")"

  return (nl', il', nodes')

processRelocate _ _ _ _ reqn _ =

  fail $ "Exchange " ++ show reqn ++ " nodes mode is not implemented"

formatRelocate :: (Node.List, Instance.List, [Ndx])

               -> Result IAllocResult

formatRelocate (nl, il, ndxs) =

    let nodes = map (`Container.find` nl) ndxs

        names = map Node.name nodes

    in Ok ("success", showJSON names, nl, il)

-- | Process a request and return new node lists.

processRequest :: Request -> Result IAllocResult

processRequest request =

  let Request rqtype (ClusterData gl nl il _) = request

  in case rqtype of

       Allocate xi reqn ->

           Cluster.tryMGAlloc gl nl il xi reqn >>= formatAllocate il

       Relocate idx reqn exnodes ->

           processRelocate gl nl il idx reqn exnodes >>= formatRelocate

       ChangeGroup gdxs idxs ->

           Cluster.tryChangeGroup gl nl il idxs gdxs >>=

                  formatNodeEvac gl nl il

       NodeEvacuate xi mode ->

           Cluster.tryNodeEvac gl nl il mode xi >>=

                  formatNodeEvac gl nl il

-- | Reads the request from the data file(s).

readRequest :: Options -> [String] -> IO Request

readRequest opts args = do

  when (null args) $ do

         hPutStrLn stderr "Error: this program needs an input file."

         exitWith $ ExitFailure 1

  input_data <- readFile (head args)

  r1 <- case parseData input_data of

          Bad err -> do

            hPutStrLn stderr $ "Error: " ++ err

            exitWith $ ExitFailure 1

          Ok (fix_msgs, rq) -> maybeShowWarnings fix_msgs >> return rq

  (if isJust (optDataFile opts) ||  (not . null . optNodeSim) opts

   then do

     cdata <- loadExternalData opts

     let Request rqt _ = r1

     return $ Request rqt cdata

   else return r1)

-- | Main iallocator pipeline.

runIAllocator :: Request -> (Maybe (Node.List, Instance.List), String)

runIAllocator request =

  let (ok, info, result, cdata) =

          case processRequest request of

            Ok (msg, r, nl, il) -> (True, "Request successful: " ++ msg, r,

                                    Just (nl, il))

            Bad msg -> (False, "Request failed: " ++ msg, JSArray [], Nothing)

      rstring = formatResponse ok info result

  in (cdata, rstring)