src/Ganeti/Objects/Disk.hs

{-# LANGUAGE TemplateHaskell, FunctionalDependencies #-}

{-| Implementation of the Ganeti Disk config object.

-}

{-

Copyright (C) 2014 Google Inc.
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-}

module Ganeti.Objects.Disk where

import Control.Applicative ((<*>), (<$>))
import Data.Char (isAsciiLower, isAsciiUpper, isDigit)
import Data.List (isPrefixOf, isInfixOf)
import Language.Haskell.TH.Syntax
import Text.JSON (showJSON, readJSON, JSValue(..))
import qualified Text.JSON as J

import Ganeti.JSON (Container, fromObj)
import Ganeti.THH
import Ganeti.THH.Field
import Ganeti.Types
import Ganeti.Utils.Validate

-- | Constant for the dev_type key entry in the disk config.
devType :: String
devType = "dev_type"

-- | The disk parameters type.
type DiskParams = Container JSValue

-- | An alias for DRBD secrets
type DRBDSecret = String

-- Represents a group name and a volume name.
--
-- From @man lvm@:
--
-- The following characters are valid for VG and LV names: a-z A-Z 0-9 + _ . -
--
-- VG  and LV names cannot begin with a hyphen.  There are also various reserved
-- names that are used internally by lvm that can not be used as LV or VG names.
-- A VG cannot be  called  anything  that exists in /dev/ at the time of
-- creation, nor can it be called '.' or '..'.  A LV cannot be called '.' '..'
-- 'snapshot' or 'pvmove'. The LV name may also not contain the strings '_mlog'
-- or '_mimage'
data LogicalVolume = LogicalVolume { lvGroup :: String
                                   , lvVolume :: String
                                   }
  deriving (Eq, Ord)

instance Show LogicalVolume where
  showsPrec _ (LogicalVolume g v) =
    showString g . showString "/" . showString v

-- | Check the constraints for a VG/LV names (except the @\/dev\/@ check).
instance Validatable LogicalVolume where
  validate (LogicalVolume g v) = do
      let vgn = "Volume group name"
      -- Group name checks
      nonEmpty vgn g
      validChars vgn g
      notStartsDash vgn g
      notIn vgn g [".", ".."]
      -- Volume name checks
      let lvn = "Volume name"
      nonEmpty lvn v
      validChars lvn v
      notStartsDash lvn v
      notIn lvn v [".", "..", "snapshot", "pvmove"]
      reportIf ("_mlog" `isInfixOf` v) $ lvn ++ " must not contain '_mlog'."
      reportIf ("_mimage" `isInfixOf` v) $ lvn ++ "must not contain '_mimage'."
    where
      nonEmpty prefix x = reportIf (null x) $ prefix ++ " must be non-empty"
      notIn prefix x =
        mapM_ (\y -> reportIf (x == y)
                              $ prefix ++ " must not be '" ++ y ++ "'")
      notStartsDash prefix x = reportIf ("-" `isPrefixOf` x)
                                 $ prefix ++ " must not start with '-'"
      validChars prefix x =
        reportIf (not . all validChar $ x)
                 $ prefix ++ " must consist only of [a-z][A-Z][0-9][+_.-]"
      validChar c = isAsciiLower c || isAsciiUpper c || isDigit c
                    || (c `elem` "+_.-")

instance J.JSON LogicalVolume where
  showJSON = J.showJSON . show
  readJSON (J.JSString s) | (g, _ : l) <- break (== '/') (J.fromJSString s) =
    either fail return . evalValidate . validate' $ LogicalVolume g l
  readJSON v = fail $ "Invalid JSON value " ++ show v
                      ++ " for a logical volume"

-- | The disk configuration type. This includes the disk type itself,
-- for a more complete consistency. Note that since in the Python
-- code-base there's no authoritative place where we document the
-- logical id, this is probably a good reference point. There is a bijective
-- correspondence between the 'DiskLogicalId' constructors and 'DiskTemplate'.
data DiskLogicalId
  = LIDPlain LogicalVolume  -- ^ Volume group, logical volume
  | LIDDrbd8 String String Int Int Int (Private DRBDSecret)
  -- ^ NodeA, NodeB, Port, MinorA, MinorB, Secret
  | LIDFile FileDriver String -- ^ Driver, path
  | LIDSharedFile FileDriver String -- ^ Driver, path
  | LIDGluster FileDriver String -- ^ Driver, path
  | LIDBlockDev BlockDriver String -- ^ Driver, path (must be under /dev)
  | LIDRados String String -- ^ Unused, path
  | LIDExt String String -- ^ ExtProvider, unique name
    deriving (Show, Eq)

-- | Mapping from a logical id to a disk type.
lidDiskType :: DiskLogicalId -> DiskTemplate
lidDiskType (LIDPlain {}) = DTPlain
lidDiskType (LIDDrbd8 {}) = DTDrbd8
lidDiskType (LIDFile  {}) = DTFile
lidDiskType (LIDSharedFile  {}) = DTSharedFile
lidDiskType (LIDGluster  {}) = DTGluster
lidDiskType (LIDBlockDev {}) = DTBlock
lidDiskType (LIDRados {}) = DTRbd
lidDiskType (LIDExt {}) = DTExt

-- | Builds the extra disk_type field for a given logical id.
lidEncodeType :: DiskLogicalId -> [(String, JSValue)]
lidEncodeType v = [(devType, showJSON . lidDiskType $ v)]

-- | Custom encoder for DiskLogicalId (logical id only).
encodeDLId :: DiskLogicalId -> JSValue
encodeDLId (LIDPlain (LogicalVolume vg lv)) =
  JSArray [showJSON vg, showJSON lv]
encodeDLId (LIDDrbd8 nodeA nodeB port minorA minorB key) =
  JSArray [ showJSON nodeA, showJSON nodeB, showJSON port
          , showJSON minorA, showJSON minorB, showJSON key ]
encodeDLId (LIDRados pool name) = JSArray [showJSON pool, showJSON name]
encodeDLId (LIDFile driver name) = JSArray [showJSON driver, showJSON name]
encodeDLId (LIDSharedFile driver name) =
  JSArray [showJSON driver, showJSON name]
encodeDLId (LIDGluster driver name) = JSArray [showJSON driver, showJSON name]
encodeDLId (LIDBlockDev driver name) = JSArray [showJSON driver, showJSON name]
encodeDLId (LIDExt extprovider name) =
  JSArray [showJSON extprovider, showJSON name]

-- | Custom encoder for DiskLogicalId, composing both the logical id
-- and the extra disk_type field.
encodeFullDLId :: DiskLogicalId -> (JSValue, [(String, JSValue)])
encodeFullDLId v = (encodeDLId v, lidEncodeType v)

-- | Custom decoder for DiskLogicalId. This is manual for now, since
-- we don't have yet automation for separate-key style fields.
decodeDLId :: [(String, JSValue)] -> JSValue -> J.Result DiskLogicalId
decodeDLId obj lid = do
  dtype <- fromObj obj devType
  case dtype of
    DTDrbd8 ->
      case lid of
        JSArray [nA, nB, p, mA, mB, k] ->
          LIDDrbd8
            <$> readJSON nA
            <*> readJSON nB
            <*> readJSON p
            <*> readJSON mA
            <*> readJSON mB
            <*> readJSON k
        _ -> fail "Can't read logical_id for DRBD8 type"
    DTPlain ->
      case lid of
        JSArray [vg, lv] -> LIDPlain <$>
          (LogicalVolume <$> readJSON vg <*> readJSON lv)
        _ -> fail "Can't read logical_id for plain type"
    DTFile ->
      case lid of
        JSArray [driver, path] ->
          LIDFile
            <$> readJSON driver
            <*> readJSON path
        _ -> fail "Can't read logical_id for file type"
    DTSharedFile ->
      case lid of
        JSArray [driver, path] ->
          LIDSharedFile
            <$> readJSON driver
            <*> readJSON path
        _ -> fail "Can't read logical_id for shared file type"
    DTGluster ->
      case lid of
        JSArray [driver, path] ->
          LIDGluster
            <$> readJSON driver
            <*> readJSON path
        _ -> fail "Can't read logical_id for shared file type"
    DTBlock ->
      case lid of
        JSArray [driver, path] ->
          LIDBlockDev
            <$> readJSON driver
            <*> readJSON path
        _ -> fail "Can't read logical_id for blockdev type"
    DTRbd ->
      case lid of
        JSArray [driver, path] ->
          LIDRados
            <$> readJSON driver
            <*> readJSON path
        _ -> fail "Can't read logical_id for rdb type"
    DTExt ->
      case lid of
        JSArray [extprovider, name] ->
          LIDExt
            <$> readJSON extprovider
            <*> readJSON name
        _ -> fail "Can't read logical_id for extstorage type"
    DTDiskless ->
      fail "Retrieved 'diskless' disk."

-- | Disk data structure.

$(buildObjectWithForthcoming "Disk" "disk" $
  [ customField 'decodeDLId 'encodeFullDLId ["dev_type"] $
      simpleField "logical_id"    [t| DiskLogicalId   |]
  , defaultField  [| [] |]
      $ simpleField "children" (return . AppT ListT . ConT $ mkName "Disk")
  , defaultField  [| [] |] $ simpleField "nodes" [t| [String] |]
  , defaultField [| "" |] $ simpleField "iv_name" [t| String |]
  , simpleField "size" [t| Int |]
  , defaultField [| DiskRdWr |] $ simpleField "mode" [t| DiskMode |]
  , optionalField $ simpleField "name" [t| String |]
  , optionalField $ simpleField "spindles" [t| Int |]
  , optionalField $ simpleField "params" [t| DiskParams |]
  ]
  ++ uuidFields
  ++ serialFields
  ++ timeStampFields)

instance UuidObject Disk where
  uuidOf = diskUuid

instance ForthcomingObject Disk where
  isForthcoming = diskForthcoming

-- | Determines whether a disk or one of his children has the given logical id
-- (determined by the volume group name and by the logical volume name).
-- This can be true only for DRBD or LVM disks.
includesLogicalId :: LogicalVolume -> Disk -> Bool
includesLogicalId lv disk =
  case diskLogicalId disk of
    Just (LIDPlain lv') -> lv' == lv
    Just (LIDDrbd8 {}) ->
      any (includesLogicalId lv) $ diskChildren disk
    _ -> False