Enhance the RAPI backend to accept file:// URLs

This will allow offline testing of this backend (except for the actual
curl part), also in the case where we didn't compile against curl.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>

htools/Ganeti/HTools/Rapi.hs

@@ -30,6 +30,7 @@ module Ganeti.HTools.Rapi
   , parseData
   ) where
 
+import Data.List (isPrefixOf)
 import Data.Maybe (fromMaybe)
 #ifndef NO_CURL
 import Network.Curl
@@ -39,6 +40,7 @@ import Control.Monad
 import Text.JSON (JSObject, fromJSObject, decodeStrict)
 import Text.JSON.Types (JSValue(..))
 import Text.Printf (printf)
+import System.FilePath
 
 import Ganeti.HTools.Loader
 import Ganeti.HTools.Types
@@ -50,6 +52,10 @@ import qualified Ganeti.Constants as C
 
 {-# ANN module "HLint: ignore Eta reduce" #-}
 
+-- | File method prefix.
+filePrefix :: String
+filePrefix = "file://"
+
 -- | Read an URL via curl and return the body if successful.
 getUrl :: (Monad m) => String -> IO (m String)
 
@@ -74,6 +80,11 @@ getUrl url = do
                  url (show code))
 #endif
 
+-- | Helper to convert I/O errors in 'Bad' values.
+ioErrToResult :: IO a -> IO (Result a)
+ioErrToResult ioaction =
+  catch (ioaction >>= return . Ok) (return . Bad . show)
+
 -- | Append the default port if not passed in.
 formatHost :: String -> String
 formatHost master =
@@ -175,9 +186,9 @@ parseCluster obj = do
   return (tags, ipolicy)
 
 -- | Loads the raw cluster data from an URL.
-readData :: String -- ^ Cluster or URL to use as source
-         -> IO (Result String, Result String, Result String, Result String)
-readData master = do
+readDataHttp :: String -- ^ Cluster or URL to use as source
+             -> IO (Result String, Result String, Result String, Result String)
+readDataHttp master = do
   let url = formatHost master
   group_body <- getUrl $ printf "%s/2/groups?bulk=1" url
   node_body <- getUrl $ printf "%s/2/nodes?bulk=1" url
@@ -185,6 +196,24 @@ readData master = do
   info_body <- getUrl $ printf "%s/2/info" url
   return (group_body, node_body, inst_body, info_body)
 
+-- | Loads the raw cluster data from the filesystem.
+readDataFile:: String -- ^ Path to the directory containing the files
+             -> IO (Result String, Result String, Result String, Result String)
+readDataFile path = do
+  group_body <- ioErrToResult $ readFile $ path </> "groups.json"
+  node_body <- ioErrToResult $ readFile $ path </> "nodes.json"
+  inst_body <- ioErrToResult $ readFile $ path </> "instances.json"
+  info_body <- ioErrToResult $ readFile $ path </> "info.json"
+  return (group_body, node_body, inst_body, info_body)
+
+-- | Loads data via either 'readDataFile' or 'readDataHttp'.
+readData :: String -- ^ URL to use as source
+         -> IO (Result String, Result String, Result String, Result String)
+readData url = do
+  if filePrefix `isPrefixOf` url
+    then readDataFile (drop (length filePrefix) url)
+    else readDataHttp url
+
 -- | Builds the cluster data from the raw Rapi content.
 parseData :: (Result String, Result String, Result String, Result String)
           -> Result ClusterData