Synnefo » snf-ganeti

{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, CPP,

  BangPatterns #-}

{-| Implementation of the RPC client.

-}

{-

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.Rpc

  ( RpcCall

  , RpcResult

  , Rpc

  , RpcError(..)

  , executeRpcCall

  , rpcCallName

  , rpcCallTimeout

  , rpcCallData

  , rpcCallAcceptOffline

  , rpcResultFill

  ) where

import qualified Text.JSON as J

#ifndef NO_CURL

import Network.Curl

#endif

import qualified Ganeti.Constants as C

import Ganeti.Objects

import Ganeti.HTools.Compat

#ifndef NO_CURL

-- | The curl options used for RPC.

curlOpts :: [CurlOption]

curlOpts = [ CurlFollowLocation False

           , CurlCAInfo C.nodedCertFile

           , CurlSSLVerifyHost 0

           , CurlSSLVerifyPeer True

           , CurlSSLCertType "PEM"

           , CurlSSLCert C.nodedCertFile

           , CurlSSLKeyType "PEM"

           , CurlSSLKey C.nodedCertFile

           , CurlConnectTimeout (fromIntegral C.rpcConnectTimeout)

           ]

#endif

-- | Data type for RPC error reporting.

data RpcError

  = CurlDisabledError

  | CurlLayerError Node String

  | JsonDecodeError String

  | OfflineNodeError Node

  deriving Eq

instance Show RpcError where

  show CurlDisabledError =

    "RPC/curl backend disabled at compile time"

  show (CurlLayerError node code) =

    "Curl error for " ++ nodeName node ++ ", error " ++ code

  show (JsonDecodeError msg) =

    "Error while decoding JSON from HTTP response " ++ msg

  show (OfflineNodeError node) =

    "Node " ++ nodeName node ++ " is marked as offline"

rpcErrorJsonReport :: (Monad m) => J.Result a -> m (Either RpcError a)

rpcErrorJsonReport (J.Error x) = return $ Left $ JsonDecodeError x

rpcErrorJsonReport (J.Ok x) = return $ Right x

-- | A generic class for RPC calls.

class (J.JSON a) => RpcCall a where

  -- | Give the (Python) name of the procedure.

  rpcCallName :: a -> String

  -- | Calculate the timeout value for the call execution.

  rpcCallTimeout :: a -> Int

  -- | Prepare arguments of the call to be send as POST.

  rpcCallData :: Node -> a -> String

  -- | Whether we accept offline nodes when making a call.

  rpcCallAcceptOffline :: a -> Bool

  rpcCallData _ = J.encode

-- | A generic class for RPC results with default implementation.

class (J.JSON a) => RpcResult a where

  -- | Create a result based on the received HTTP response.

  rpcResultFill :: (Monad m) => String -> m (Either RpcError a)

  rpcResultFill res = rpcErrorJsonReport $  J.decode res

-- | Generic class that ensures matching RPC call with its respective

-- result.

class (RpcCall a, RpcResult b) => Rpc a b | a -> b

-- | Http Request definition.

data HttpClientRequest = HttpClientRequest

  { requestTimeout :: Int

  , requestUrl :: String

  , requestPostData :: String

  }

-- | Execute the request and return the result as a plain String. When

-- curl reports an error, we propagate it.

executeHttpRequest :: Node -> Either RpcError HttpClientRequest

                   -> IO (Either RpcError String)

executeHttpRequest _ (Left rpc_err) = return $ Left rpc_err

#ifdef NO_CURL

executeHttpRequest _ _ = return $ Left CurlDisabledError

#else

executeHttpRequest node (Right request) = do

  let reqOpts = [ CurlTimeout (fromIntegral $ requestTimeout request)

                , CurlPostFields [requestPostData request]

                ]

      url = requestUrl request

  -- FIXME: This is very similar to getUrl in Htools/Rapi.hs

  (code, !body) <- curlGetString url $ curlOpts ++ reqOpts

  case code of

    CurlOK -> return $ Right body

    _ -> return $ Left $ CurlLayerError node (show code)

#endif

-- | Prepare url for the HTTP request.

prepareUrl :: (RpcCall a) => Node -> a -> String

prepareUrl node call =

  let node_ip = nodePrimaryIp node

      port = snd C.daemonsPortsGanetiNoded

      path_prefix = "https://" ++ (node_ip) ++ ":" ++ (show port) in

  path_prefix ++ "/" ++ rpcCallName call

-- | Create HTTP request for a given node provided it is online,

-- otherwise create empty response.

prepareHttpRequest ::  (RpcCall a) => Node -> a

                   -> Either RpcError HttpClientRequest

prepareHttpRequest node call

  | rpcCallAcceptOffline call ||

    (not $ nodeOffline node) =

      Right $ HttpClientRequest { requestTimeout = rpcCallTimeout call

                                , requestUrl = prepareUrl node call

                                , requestPostData = rpcCallData node call

                                }

  | otherwise = Left $ OfflineNodeError node

-- | Parse the response or propagate the error.

parseHttpResponse :: (Monad m, RpcResult a) => Either RpcError String

                  -> m (Either RpcError a)

parseHttpResponse (Left err) = return $ Left err

parseHttpResponse (Right response) = rpcResultFill response

-- | Execute RPC call for a sigle node.

executeSingleRpcCall :: (Rpc a b) => Node -> a -> IO (Node, Either RpcError b)

executeSingleRpcCall node call = do

  let request = prepareHttpRequest node call

  response <- executeHttpRequest node request

  result <- parseHttpResponse response

  return (node, result)

-- | Execute RPC call for many nodes in parallel.

executeRpcCall :: (Rpc a b) => [Node] -> a -> IO [(Node, Either RpcError b)]

executeRpcCall nodes call =

  sequence $ parMap rwhnf (uncurry executeSingleRpcCall)

               (zip nodes $ repeat call)