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{-| Cluster rolling maintenance helper.

-}

{-

Copyright (C) 2012 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.Program.Hroller

  ( main

  , options

  , arguments

  ) where

import Control.Applicative

import Control.Monad

import Data.List

import Data.Ord

import qualified Data.IntMap as IntMap

import qualified Ganeti.HTools.Container as Container

import qualified Ganeti.HTools.Node as Node

import qualified Ganeti.HTools.Group as Group

import Ganeti.Common

import Ganeti.HTools.CLI

import Ganeti.HTools.ExtLoader

import Ganeti.HTools.Graph

import Ganeti.HTools.Loader

import Ganeti.Utils

-- | Options list and functions.

options :: IO [OptType]

options = do

  luxi <- oLuxiSocket

  return

    [ luxi

    , oRapiMaster

    , oDataFile

    , oIAllocSrc

    , oOfflineNode

    , oVerbose

    , oQuiet

    , oNoHeaders

    , oSaveCluster

    , oGroup

    , oForce

    ]

-- | The list of arguments supported by the program.

arguments :: [ArgCompletion]

arguments = []

-- | Gather statistics for the coloring algorithms.

-- Returns a string with a summary on how each algorithm has performed,

-- in order of non-decreasing effectiveness, and whether it tied or lost

-- with the previous one.

getStats :: [(String, ColorVertMap)] -> String

getStats colorings = snd . foldr helper (0,"") $ algBySize colorings

    where algostat (algo, cmap) = algo ++ ": " ++ size cmap ++ grpsizes cmap

          size cmap = show (IntMap.size cmap) ++ " "

          grpsizes cmap =

            "(" ++ commaJoin (map (show.length) (IntMap.elems cmap)) ++ ")"

          algBySize = sortBy (flip (comparing (IntMap.size.snd)))

          helper :: (String, ColorVertMap) -> (Int, String) -> (Int, String)

          helper el (0, _) = ((IntMap.size.snd) el, algostat el)

          helper el (old, str)

            | old == elsize = (elsize, str ++ " TIE " ++ algostat el)

            | otherwise = (elsize, str ++ " LOOSE " ++ algostat el)

              where elsize = (IntMap.size.snd) el

-- | Predicate of belonging to a given group restriction.

hasGroup :: Maybe Group.Group -> Node.Node -> Bool

hasGroup Nothing _ = True

hasGroup (Just grp) node = Node.group node == Group.idx grp 

-- | Put the master node last.

-- Reorder a list of lists of nodes such that the master node (if present)

-- is the last node of the last group.

masterLast :: [[Node.Node]] -> [[Node.Node]]

masterLast rebootgroups =

  map (uncurry (++)) . uncurry (++) . partition (null . snd) $

  map (partition (not . Node.isMaster)) rebootgroups

-- | Main function.

main :: Options -> [String] -> IO ()

main opts args = do

  unless (null args) $ exitErr "This program doesn't take any arguments."

  let verbose = optVerbose opts

      maybeExit = if optForce opts then warn else exitErr

  -- Load cluster data. The last two arguments, cluster tags and ipolicy, are

  -- currently not used by this tool.

  ini_cdata@(ClusterData gl fixed_nl ilf _ _) <- loadExternalData opts

  let master_names = map Node.name . filter Node.isMaster . IntMap.elems $

                     fixed_nl

  case master_names of

    [] -> maybeExit "No master node found (maybe not supported by backend)."

    [ _ ] -> return ()

    _ -> exitErr $ "Found more than one master node: " ++  show master_names

  nlf <- setNodeStatus opts fixed_nl

  maybeSaveData (optSaveCluster opts) "original" "before hroller run" ini_cdata

  -- Find the wanted node group, if any.

  wantedGroup <- case optGroup opts of

    Nothing -> return Nothing

    Just name -> case Container.findByName gl name of

      Nothing -> exitErr "Cannot find target group."

      Just grp -> return (Just grp)

  let nodes = IntMap.filter

              (liftA2 (&&) (not . Node.offline) (hasGroup wantedGroup))

              nlf

  -- TODO: fail if instances are running (with option to warn only)

  nodeGraph <- case Node.mkNodeGraph nodes ilf of

                     Nothing -> exitErr "Cannot create node graph"

                     Just g -> return g

  when (verbose > 2) . putStrLn $ "Node Graph: " ++ show nodeGraph

  let colorAlgorithms = [ ("LF", colorLF)

                        , ("Dsatur", colorDsatur)

                        , ("Dcolor", colorDcolor)

                        ]

      colorings = map (\(v,a) -> (v,(colorVertMap.a) nodeGraph)) colorAlgorithms

      smallestColoring =

        (snd . minimumBy (comparing (IntMap.size . snd))) colorings

      idToNode = (`Container.find` nodes)

      nodesRebootGroups =

        map (map idToNode . filter (`IntMap.member` nodes)) $

        IntMap.elems smallestColoring

      outputRebootGroups = masterLast nodesRebootGroups

      outputRebootNames = map (map Node.name) outputRebootGroups

  when (verbose > 1) . putStrLn $ getStats colorings

  unless (optNoHeaders opts) $

         putStrLn "'Node Reboot Groups'"

  mapM_ (putStrLn . commaJoin) outputRebootNames