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{-| DRBD data collector.

-}

{-

Copyright (C) 2012, 2013 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.DataCollectors.Drbd

  ( main

  , options

  , arguments

  , dcName

  , dcVersion

  , dcFormatVersion

  ) where

import qualified Control.Exception as E

import Control.Monad

import Data.Attoparsec.Text.Lazy as A

import Data.Maybe

import Data.Text.Lazy (pack, unpack)

import Network.BSD (getHostName)

import qualified Text.JSON as J

import qualified Ganeti.BasicTypes as BT

import qualified Ganeti.Constants as C

import Ganeti.Block.Drbd.Parser(drbdStatusParser)

import Ganeti.Block.Drbd.Types(DrbdInstMinor)

import Ganeti.Common

import Ganeti.Confd.Client

import Ganeti.Confd.Types

import Ganeti.DataCollectors.CLI

import Ganeti.DataCollectors.Types

import Ganeti.Utils

-- | The default path of the DRBD status file.

-- It is hardcoded because it is not likely to change.

defaultFile :: FilePath

defaultFile = C.drbdStatusFile

-- | The default setting for the maximum amount of not parsed character to

-- print in case of error.

-- It is set to use most of the screen estate on a standard 80x25 terminal.

-- TODO: add the possibility to set this with a command line parameter.

defaultCharNum :: Int

defaultCharNum = 80*20

-- | The name of this data collector.

dcName :: String

dcName = "drbd"

-- | The version of this data collector.

dcVersion :: DCVersion

dcVersion = DCVerBuiltin

-- | The version number for the data format of this data collector.

dcFormatVersion :: Int

dcFormatVersion = 1

-- * Command line options

options :: IO [OptType]

options =

  return

    [ oDrbdStatus

    , oDrbdPairing

    ]

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

arguments :: [ArgCompletion]

arguments = [ArgCompletion OptComplFile 0 (Just 0)]

-- | Get information about the pairing of DRBD minors and Ganeti instances

-- on the current node. The information is taken from the Confd client

-- or, if a filename is specified, from a JSON encoded file (for testing

-- purposes).

getPairingInfo :: Maybe String -> IO (BT.Result [DrbdInstMinor])

getPairingInfo Nothing = do

  curNode <- getHostName

  client <- getConfdClient Nothing Nothing

  reply <- query client ReqNodeDrbd $ PlainQuery curNode

  return $

    case fmap (J.readJSONs . confdReplyAnswer) reply of

      Just (J.Ok instMinor) -> BT.Ok instMinor

      Just (J.Error msg) -> BT.Bad msg

      Nothing -> BT.Bad "No answer from the Confd server"

getPairingInfo (Just filename) = do

  content <- readFile filename

  return $

    case J.decode content of

      J.Ok instMinor -> BT.Ok instMinor

      J.Error msg -> BT.Bad msg

-- | This function builds a report with the DRBD status.

buildDRBDReport :: FilePath -> Maybe FilePath -> IO DCReport

buildDRBDReport statusFile pairingFile = do

  contents <-

    ((E.try $ readFile statusFile) :: IO (Either IOError String)) >>=

      exitIfBad "reading from file" . either (BT.Bad . show) BT.Ok

  pairingResult <- getPairingInfo pairingFile

  pairing <- exitIfBad "Can't get pairing info" pairingResult

  jsonData <-

    case A.parse (drbdStatusParser pairing) $ pack contents of

      A.Fail unparsedText contexts errorMessage -> exitErr $

        show (Prelude.take defaultCharNum $ unpack unparsedText) ++ "\n"

          ++ show contexts ++ "\n" ++ errorMessage

      A.Done _ drbdStatus -> return $ J.showJSON drbdStatus

  buildReport dcName dcVersion dcFormatVersion jsonData

-- | Main function.

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

main opts args = do

  let statusFile = fromMaybe defaultFile $ optDrbdStatus opts

      pairingFile = optDrbdPairing opts

  unless (null args) . exitErr $ "This program takes exactly zero" ++

                                  " arguments, got '" ++ unwords args ++ "'"

  report <- buildDRBDReport statusFile pairingFile

  putStrLn $ J.encode report