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{-| Small module holding program definitions.
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-}
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{-
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Copyright (C) 2011, 2012 Google Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA.
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-}
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module Ganeti.HTools.Program.Main
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  ( personalities
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  , main
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  ) where
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import Control.Exception
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import Control.Monad (guard)
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import Data.Char (toLower)
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import System.Environment
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import System.IO
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import System.IO.Error (isDoesNotExistError)
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import Ganeti.Common (formatCommands, PersonalityList)
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import Ganeti.HTools.CLI (Options, parseOpts, genericOpts)
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import qualified Ganeti.HTools.Program.Hail as Hail
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import qualified Ganeti.HTools.Program.Hbal as Hbal
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import qualified Ganeti.HTools.Program.Hcheck as Hcheck
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import qualified Ganeti.HTools.Program.Hscan as Hscan
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import qualified Ganeti.HTools.Program.Hspace as Hspace
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import qualified Ganeti.HTools.Program.Hinfo as Hinfo
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import qualified Ganeti.HTools.Program.Hroller as Hroller
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import Ganeti.Utils
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-- | Supported binaries.
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personalities :: PersonalityList Options
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personalities =
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  [ ("hail",    (Hail.main,    Hail.options,    Hail.arguments,
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                 "Ganeti IAllocator plugin that implements the instance\
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                 \ placement and movement using the same algorithm as\
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                 \ hbal(1)"))
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  , ("hbal",    (Hbal.main,    Hbal.options,    Hbal.arguments,
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                 "cluster balancer that looks at the current state of\
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                 \ the cluster and computes a series of steps designed\
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                 \ to bring the cluster into a better state"))
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  , ("hcheck",  (Hcheck.main,  Hcheck.options,  Hcheck.arguments,
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                "cluster checker; prints information about cluster's\
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                \ health and checks whether a rebalance done using\
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                \ hbal would help"))
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  , ("hscan",   (Hscan.main,   Hscan.options,   Hscan.arguments,
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                "tool for scanning clusters via RAPI and saving their\
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                \ data in the input format used by hbal(1) and hspace(1)"))
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  , ("hspace",  (Hspace.main,  Hspace.options,  Hspace.arguments,
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                "computes how many additional instances can be fit on a\
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                \ cluster, while maintaining N+1 status."))
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  , ("hinfo",   (Hinfo.main,   Hinfo.options,   Hinfo.arguments,
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                "cluster information printer; it prints information\
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                \ about the current cluster state and its residing\
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                \ nodes/instances"))
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  , ("hroller", (Hroller.main, Hroller.options, Hroller.arguments,
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                "cluster rolling maintenance helper; it helps scheduling\
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                \ node reboots in a manner that doesn't conflict with the\
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                \ instances' topology"))
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  ]
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-- | Display usage and exit.
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usage :: String -> IO ()
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usage name = do
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  hPutStrLn stderr $ "Unrecognised personality '" ++ name ++ "'."
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  hPutStrLn stderr "This program must be installed under one of the following\
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                   \ names:"
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  hPutStrLn stderr . unlines $ formatCommands personalities
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  exitErr "Please either rename/symlink the program or set\n\
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          \the environment variable HTOOLS to the desired role."
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main :: IO ()
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main = do
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  binary <- catchJust (guard . isDoesNotExistError)
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            (getEnv "HTOOLS") (const getProgName)
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  let name = map toLower binary
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  case name `lookup` personalities of
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    Nothing -> usage name
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    Just (fn, options, arguments, _) -> do
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         cmd_args <- getArgs
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         real_options <- options
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         (opts, args) <- parseOpts cmd_args name (real_options ++ genericOpts)
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                           arguments
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         fn opts args