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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.Function

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.Instance as Instance

import qualified Ganeti.HTools.Group as Group

import Ganeti.BasicTypes

import Ganeti.Common

import Ganeti.HTools.CLI

import Ganeti.HTools.ExtLoader

import Ganeti.HTools.Graph

import Ganeti.HTools.Loader

import Ganeti.HTools.Types

import Ganeti.Utils

-- | Options list and functions.

options :: IO [OptType]

options = do

  luxi <- oLuxiSocket

  return

    [ luxi

    , oRapiMaster

    , oDataFile

    , oIAllocSrc

    , oOfflineNode

    , oOfflineMaintenance

    , oVerbose

    , oQuiet

    , oNoHeaders

    , oNodeTags

    , oSaveCluster

    , oGroup

    , oSkipNonRedundant

    , oIgnoreNonRedundant

    , oForce

    , oOneStepOnly

    ]

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

arguments :: [ArgCompletion]

arguments = []

-- | Compute the result of moving an instance to a different node.

move :: Idx -> Ndx -> (Node.List, Instance.List)

        -> OpResult (Node.List, Instance.List)

move idx new_ndx (nl, il) = do

  let new_node = Container.find new_ndx nl

      inst = Container.find idx il

      old_ndx = Instance.pNode inst

      old_node = Container.find old_ndx nl

  new_node' <- Node.addPriEx True new_node inst

  let old_node' = Node.removePri old_node inst

      inst' = Instance.setPri inst new_ndx

      nl' = Container.addTwo old_ndx old_node' new_ndx new_node' nl

      il' = Container.add idx inst' il

  return (nl', il')

-- | Move an instance to one of the candidate nodes mentioned.

locateInstance :: Idx -> [Ndx] -> (Node.List, Instance.List)

                  -> Result (Node.List, Instance.List)

locateInstance idx ndxs conf =

  msum $ map (opToResult . flip (move idx) conf) ndxs

-- | Move a list of instances to some of the candidate nodes mentioned.

locateInstances :: [Idx] -> [Ndx] -> (Node.List, Instance.List)

                   -> Result (Node.List, Instance.List)

locateInstances idxs ndxs conf =

  foldM (\ cf idx -> locateInstance idx ndxs cf) conf idxs

-- | Greedily move the non-redundant instances away from a list of nodes.

-- The arguments are the list of nodes to be cleared, a list of nodes the

-- instances can be moved to, and an initial configuration. Returned is a

-- list of nodes that can be cleared simultaneously and the configuration

-- after these nodes are cleared.

clearNodes :: [Ndx] -> [Ndx] -> (Node.List, Instance.List)

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

clearNodes [] _ conf = return ([], conf)

clearNodes (ndx:ndxs) targets conf = withFirst `mplus` withoutFirst where

  withFirst = do

     let othernodes = delete ndx targets

     conf' <- locateInstances (nonRedundant conf ndx) othernodes conf

     (ndxs', conf'') <- clearNodes ndxs othernodes conf'

     return (ndx:ndxs', conf'')

  withoutFirst = clearNodes ndxs targets conf

-- | Parition a list of nodes into chunks according cluster capacity.

partitionNonRedundant :: [Ndx] -> [Ndx] -> (Node.List, Instance.List)

                         -> Result [[Ndx]]

partitionNonRedundant [] _ _ = return []

partitionNonRedundant ndxs targets conf = do

  (grp, _) <- clearNodes ndxs targets conf

  guard . not . null $ grp

  let remaining = ndxs \\ grp

  part <- partitionNonRedundant remaining targets conf

  return $ grp : part

-- | 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

-- | Predicate of having at least one tag in a given set.

hasTag :: Maybe [String] -> Node.Node -> Bool

hasTag Nothing _ = True

hasTag (Just tags) node = not . null $ Node.nTags node `intersect` tags

-- | From a cluster configuration, get the list of non-redundant instances

-- of a node.

nonRedundant :: (Node.List, Instance.List) -> Ndx -> [Idx]

nonRedundant (nl, il) ndx =

  filter (not . Instance.hasSecondary . flip Container.find  il) $

  Node.pList (Container.find ndx nl)

-- | Within a cluster configuration, decide if the node hosts non-redundant

-- Instances.

noNonRedundant :: (Node.List, Instance.List) -> Node.Node -> Bool

noNonRedundant conf = null . nonRedundant conf . Node.idx

-- | 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 (foldl (liftA2 (&&)) (const True)

                             [ not . Node.offline

                             , if optSkipNonRedundant opts

                                  then noNonRedundant (nlf, ilf)

                                  else const True

                             , hasTag $ optNodeTags opts

                             , hasGroup wantedGroup ])

              nlf

      mkGraph = if optOfflineMaintenance opts

                   then Node.mkNodeGraph

                   else Node.mkRebootNodeGraph nlf

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

  nodeGraph <- case mkGraph 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 = IntMap.elems $

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

      allNdx = map Node.idx $ Container.elems nlf

      splitted = mapM (\ grp -> partitionNonRedundant grp allNdx (nlf,ilf))

                 smallestColoring

  rebootGroups <- if optIgnoreNonRedundant opts

                     then return smallestColoring

                     else case splitted of

                            Ok splitgroups -> return $ concat splitgroups

                            Bad _ -> exitErr "Not enough capacity to move\ 

                                             \ non-redundant instances"

  let idToNode = (`Container.find` nodes)

      nodesRebootGroups =

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

      outputRebootGroups = masterLast .

                           sortBy (flip compare `on` length) $

                           nodesRebootGroups

      outputRebootNames = map (map Node.name) outputRebootGroups

  when (verbose > 1) . putStrLn $ getStats colorings

  if optOneStepOnly opts

     then do

       unless (optNoHeaders opts) $

              putStrLn "'First Reboot Group'"

       case outputRebootNames of

         [] -> return ()

         y : _ -> mapM_ putStrLn y

     else do

       unless (optNoHeaders opts) $

              putStrLn "'Node Reboot Groups'"

       mapM_ (putStrLn . commaJoin) outputRebootNames