{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE NamedFieldPuns #-}
{-# LANGUAGE PatternGuards #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TypeApplications #-}
-- | This module runs a Hiera server that caches Hiera data. There is
-- a huge caveat : only the data files are watched for changes, not the main configuration file.
--
-- A minor bug is that interpolation will not work for inputs containing the % character when it isn't used for interpolation.
module Hiera.Server
( startHiera,
dummyHiera,
HieraQueryType (..),
readQueryType,
HieraQueryFunc,
varSplitter,
HieraVar (..),
mergeWith,
)
where
import Data.Aeson
import qualified Data.Aeson as Aeson
import Data.Aeson.Lens (_Key)
import qualified Data.Attoparsec.Text as AT
import qualified Data.ByteString.Lazy as BS
import qualified Data.ByteString.Lazy.Char8 as BS8
import qualified Data.Either.Strict as S
import qualified Data.FileCache as Cache
import qualified Data.List as List
import qualified Data.Text as Text
import qualified Data.Vector as Vector
import qualified Data.Yaml as Yaml
import Puppet.Language
import qualified System.Directory as Directory
import qualified System.FilePath as FilePath
import System.FilePath.Lens (directory)
import Text.Megaparsec (Parsec, parse, satisfy, sepBy, sepBy1)
import Text.Megaparsec.Char (char, space)
import XPrelude hiding (space)
-- | The different kind of hiera queries.
data HieraQueryType
= -- | The first match in the hierarchy is returned.
QFirst
| -- | Combines array and scalar values to return a merged, flattened array with all duplicate removed.
QUnique
| -- | Combines the keys and values of any number of hashes to return a merged hash.
-- | Use of an Hash to specify the merge behavior
QHash
| QDeep
{ _knockoutPrefix :: Maybe Text,
_sortMerged :: Bool,
_mergeHashArray :: Bool
}
deriving (Show)
readQueryType :: Text -> Maybe HieraQueryType
readQueryType s =
case s of
"first" -> Just QFirst
"unique" -> Just QUnique
"hash" -> Just QHash
_ -> Nothing
-- | The type of the Hiera API function associated to given hierarchy.
type HieraQueryFunc m =
-- | Scope: all variables that Hiera can interpolate (the top level ones are prefixed with '::')
Container PValue ->
-- | The query
Text ->
HieraQueryType ->
ExceptT PrettyError m (Maybe PValue)
data Backend
= YamlBackend FilePath
| JsonBackend FilePath
deriving (Show)
data HieraStringPart
= HPString Text
| HPVariable Text
deriving (Show)
instance Pretty HieraStringPart where
pretty (HPString t) = ppline t
pretty (HPVariable v) = dullred (ppline ("%{" <> v <> "}"))
prettyList = mconcat . map pretty
newtype InterpolableHieraString = InterpolableHieraString
{ getInterpolableHieraString :: [HieraStringPart]
}
deriving (Show)
data HieraVar
= HieraVar (NonEmpty Text)
| HieraFunction (NonEmpty Text) [Text]
deriving (Show, Eq)
varSplitter ::
Text ->
-- | returns variable parts, function arguments
HieraVar
varSplitter v =
case parse parser "dummy" v of
Left _ -> HieraVar (v :| [])
Right hv -> hv
where
parser :: Parsec Void Text HieraVar
parser = do
x : xs <- vpart `sepBy1` char '.'
let nms = x :| xs
margs <-
optional
( char '('
*> space
*> (arg `sepBy` (space *> char ',' *> space))
<* space
<* char ')'
)
pure $ case margs of
Nothing -> HieraVar nms
Just args -> HieraFunction nms args
arg = squotev <|> dquotev
vpart = squotev <|> dquotev <|> rawv
rawv = Text.pack <$> some (satisfy (\c -> c /= '.' && c /= '('))
-- TODO, escapes
squotev = Text.pack <$> (char '\'' *> some (satisfy (/= '\'')) <* char '\'')
dquotev = Text.pack <$> (char '"' *> some (satisfy (/= '"')) <* char '"')
resolveString :: Container PValue -> InterpolableHieraString -> Maybe Text
resolveString vars = fmap Text.concat . mapM resolve . getInterpolableHieraString
where
resolve (HPString x) = Just x
resolve (HPVariable v) = vars ^? ix v . _PString
instance FromJSON InterpolableHieraString where
parseJSON (String s) = case parseInterpolableString s of
Right x -> return (InterpolableHieraString x)
Left rr -> fail rr
parseJSON _ = fail "Invalid value type"
-- | An attoparsec parser that turns text into parts that are ready for interpolation.
interpolableString :: AT.Parser [HieraStringPart]
interpolableString = AT.many1 (fmap HPString rawPart <|> fmap HPVariable interpPart)
where
rawPart = AT.takeWhile1 (/= '%')
interpPart = AT.string "%{" *> AT.takeWhile (/= '}') <* AT.char '}'
parseInterpolableString :: Text -> Either String [HieraStringPart]
parseInterpolableString = AT.parseOnly interpolableString
data HieraConfigFile = HieraConfigFile
{ _version :: Int,
_backends :: [Backend],
_hierarchy :: [InterpolableHieraString]
}
deriving (Show)
data QRead = QRead
{ _qvars :: Container PValue,
_qtype :: HieraQueryType,
_qhier :: [Value]
}
makeLenses ''QRead
instance FromJSON HieraConfigFile where
parseJSON =
let mkHiera5 :: Object -> Yaml.Parser HieraConfigFile
mkHiera5 v = do
-- we currently only read the first hierarchy entry to get the hiera path
-- TODO: change the definition of HieraConfigFile to be [(Backend, InterpolableHieraString)]
-- to allow defining a Backend per hierarchies
let paths = Object v ^.. key "hierarchy" . avalues . key "paths" . avalues
path = Object v ^.. key "hierarchy" . avalues . key "path"
hierarchy_value <- case Object v ^? key "hierarchy" . nth 0 of
Just (Object h) -> pure h
_ -> fail "Hiera config should define at least one hierarchy"
datadir <-
hierarchy_value .:? "datadir" >>= \case
Just (String dir) -> pure dir
Just _ -> fail "datadir should be a string"
Nothing -> pure $ Object v ^. key "defaults" . key "datadir" . _String
HieraConfigFile 5 [YamlBackend (toS datadir)] -- TODO: support other backends if needed
<$> mapM parseJSON (paths <> path)
mkHiera3 v =
HieraConfigFile 3
<$> (v .:? ":backends" .!= ["yaml"] >>= mapM mkBackend3)
<*> (v .:? ":hierarchy" .!= [InterpolableHieraString [HPString "common"]])
where
mkBackend3 :: Text -> Yaml.Parser Backend
mkBackend3 name = do
(backendConstructor, skey) <- case name of
"yaml" -> return (YamlBackend, ":yaml")
"json" -> return (JsonBackend, ":json")
_ -> fail ("Unknown backend " <> toS name)
datadir <- case Object v ^? key skey . key ":datadir" of
Just (String dir) -> return dir
Just _ -> fail ":datadir should be a string"
Nothing -> return "/etc/puppet/hieradata"
pure (backendConstructor (toS datadir))
in Aeson.withObject "v3 or v5" $ \o ->
o .:? "version" >>= \case
Just (5 :: Int) -> mkHiera5 o
Just _ -> fail "Hiera configuration version different than 5 is not supported."
Nothing -> mkHiera3 o
type Cache = Cache.FileCacheR String Value
-- | The only method you'll ever need. It runs a Hiera server and gives you a querying function.
-- | All IO exceptions are thrown directly including ParsingException.
startHiera :: String -> FilePath -> IO (HieraQueryFunc IO)
startHiera layer fp =
Yaml.decodeFileEither fp >>= \case
Left (Yaml.AesonException "Error in $: Hiera configuration version different than 5 is not supported.") -> do
logInfoStr ("Detect a hiera configuration format in " <> fp <> " at version 4. This format is not recognized. Using a dummy hiera.")
pure dummyHiera
Left ex -> panic (show ex)
Right cfg@HieraConfigFile {..} -> do
logInfoStr ("Detect a hiera " <> layer <> " configuration format in " <> fp <> " at version " <> show _version)
query cfg fp <$> Cache.newFileCache
-- | A dummy hiera function that will be used when hiera is not detected.
dummyHiera :: (Monad m) => HieraQueryFunc m
dummyHiera _ _ _ = pure Nothing
exceptt :: (Applicative m) => Except r a -> ExceptT r m a
exceptt = ExceptT . pure . runExcept
query :: HieraConfigFile -> FilePath -> Cache -> HieraQueryFunc IO
query HieraConfigFile {_version, _backends, _hierarchy} fp cache vars hquery qt = do
-- step 1, resolve hierarchies
let searchin = do
mhierarchy <- resolveString vars <$> _hierarchy
Just h <- [mhierarchy]
backend <- _backends
let decodeInfo :: (FilePath -> IO (Either String Value), String, String)
decodeInfo =
case backend of
JsonBackend dir -> (fmap Aeson.eitherDecode' . BS.readFile, dir, ".json")
YamlBackend dir -> (fmap (_Left %~ show) . Yaml.decodeFileEither, dir, ".yaml")
pure (decodeInfo, toS h)
-- step 2, read all the files, returning a raw data structure
mvals <- liftIO $ forM searchin $ \((decodefunction, datadir, extension), h) -> do
let extension' =
if snd (FilePath.splitExtension h) == ".yaml"
then ""
else extension
filename = basedir <> datadir <> "/" <> h <> extension'
basedir = case datadir of
'/' : _ -> mempty
_ -> fp ^. directory <> "/"
querycache = do
efilecontent <- Cache.query cache filename (strictifyEither <$> decodefunction filename)
case efilecontent of
S.Left r -> do
logWarningStr $ "Hiera: error when reading file " <> filename <> ": " <> r
pure Nothing
S.Right val -> pure (Just val)
ifM
(Directory.doesFileExist filename)
querycache
(pure Nothing)
let vals = catMaybes mvals
-- step 3, query through all the results
liftIO $ logDebugStr ("Looking up '" <> toS hquery <> "' with backends " <> List.unwords (fmap show _backends))
exceptt $ runReaderT (recursiveQuery hquery []) (QRead vars qt vals)
type QM a = ReaderT QRead (Except PrettyError) a
checkLoop :: Text -> [Text] -> QM ()
checkLoop x xs =
when (x `elem` xs) (throwError ("Loop in hiera: " <> fromString (Text.unpack (Text.intercalate ", " (x : xs)))))
-- a helper function that removes prefix and suffix
textBetween ::
-- | prefix
Text ->
-- | suffix
Text ->
Text ->
Maybe Text
textBetween pr su = Text.stripPrefix pr >=> Text.stripSuffix su
recursiveQuery :: Text -> [Text] -> QM (Maybe PValue)
recursiveQuery curquery prevqueries =
case varSplitter curquery of
HieraFunction _ _ -> throwError "Hiera functions not yet handled here (A)"
HieraVar (varname :| allkeys) -> do
checkLoop varname prevqueries
rawlookups <- mapMaybe (preview (key (varname ^. _Key))) <$> view qhier
let lookupKeys keys v =
case keys of
[] -> pure v
k : ks ->
case v of
Object hs ->
case hs ^? ix k of
Nothing -> Nothing
Just v' -> lookupKeys ks v'
_ -> Nothing
rlookups <- mapM (resolveValue (varname : prevqueries)) rawlookups
let lookups = mapMaybe (lookupKeys (allkeys ^.. traversed . _Key)) rlookups
case traverse Aeson.fromJSON lookups of
Aeson.Error rr -> throwError ("Something horrible happened in recursiveQuery: " <> fromString rr)
Aeson.Success [] ->
if null rlookups
then return Nothing
else throwError ("Could not lookup " <> fromString (Text.unpack curquery) <> " in " <> PrettyError (list (map (fromString . BS8.unpack . encode) rlookups)))
Aeson.Success (x : xs) -> do
qt <- view qtype
Just <$> foldM (mergeWith qt) x xs
resolveValue :: [Text] -> Value -> QM Value
resolveValue prevqueries value =
case value of
String t | Just alias <- Text.stripPrefix "%{alias('" t >>= Text.stripSuffix "')}" -> do
mr <- recursiveQuery alias (("alias:" <> alias) : prevqueries)
case mr of
Nothing -> throwError ("Could not alias " <> fromString (Text.unpack alias))
Just r -> pure (toJSON r)
String t -> String <$> resolveText prevqueries t
Array arr -> Array <$> mapM (resolveValue prevqueries) arr
Object hh -> Object <$> mapM (resolveValue prevqueries) hh
_ -> return value
resolveText :: [Text] -> Text -> QM Text
resolveText prevqueries t =
case parseInterpolableString t of
Right qparts -> Text.concat <$> mapM (resolveStringPart prevqueries) qparts
Left _ -> return t
resolveStringPart :: [Text] -> HieraStringPart -> QM Text
resolveStringPart prevqueries sp =
case sp of
HPString s -> return s
HPVariable "" -> return ""
HPVariable varname -> do
let rc vars val =
case vars of
[] -> pure val
v : vs -> case val of
PHash m -> m ^? ix v >>= rc vs
_ -> Nothing
extractFunction txt =
textBetween (txt <> "('") "')" varname
<|> textBetween (txt <> "(\"") "\")" varname
r <- case extractFunction "lookup" <|> extractFunction "hiera" <|> extractFunction "alias" of
Just lk -> recursiveQuery lk prevqueries
Nothing -> do
vmap <- view qvars
case varSplitter varname of
HieraVar (mvar :| svars) -> pure (vmap ^? ix mvar >>= rc svars)
HieraFunction (fname :| []) args ->
case fname of
"literal" ->
case args of
[x] -> pure (Just (PString x))
_ -> throwError "The literal function expects a single argument"
_ -> throwError ("Unknown function " <> fromString (Text.unpack fname))
HieraFunction (fname :| xs) _ ->
throwError
( "Malformed function name: "
<> fromString (Text.unpack (Text.intercalate "." (fname : xs)))
)
case r of
Just (PString v) -> return v
Just (PNumber s) -> pure (scientific2text s)
Just pvalue -> throwError (PrettyError ("Variable lookup for " <> fromString (Text.unpack varname) <> " did not return a string, but " <> pretty pvalue))
_ -> throwError ("Could not lookup variable " <> fromString (Text.unpack varname))
mergeWith :: (MonadError PrettyError m) => HieraQueryType -> PValue -> PValue -> m PValue
mergeWith qt cur new =
case qt of
QFirst -> return cur
QUnique ->
let getArray x = case x of
PArray array -> Vector.toList array
_ -> [x]
curarray = getArray cur
newarray = getArray new
in case new of
PHash _ -> throwError "Tried to merge a hash"
_ -> return (PArray (Vector.fromList (List.nub (curarray ++ newarray))))
QHash -> case (cur, new) of
(PHash curh, PHash newh) -> return (PHash (curh <> newh))
_ -> throwError (PrettyError ("Tried to merge things that are not hashes: " <> ppline (show cur) <+> ppline (show new)))
QDeep {} -> throwError "deep queries not supported"