diff --git a/src/Stackage/Config.hs b/src/Stackage/Config.hs
index 059edab0..2fb57941 100644
--- a/src/Stackage/Config.hs
+++ b/src/Stackage/Config.hs
@@ -1,7 +1,260 @@
-{-# LANGUAGE EmptyDataDecls #-}
+-- | The general Stackage configuration that starts everything off. This should
+-- be smart to falback if there is no stackage.config, instead relying on 
+-- whatever files are available.
+--
+-- If there is no stackage.config, and there is a cabal.config, we
+-- read in those constraints, and if there's a cabal.sandbox.config,
+-- we read any constraints from there and also find the package
+-- database from there, etc. And if there's nothing, we should
+-- probably default to behaving like cabal, possibly with spitting out
+-- a warning that "you should run `stk init` to make things better".
+module Stackage.Config (
+    Config
+  , Settings
+  , getConfig
+  , NotYetImplemented(..)
+  ) where
 
--- |
+import Control.Applicative
+import Control.Exception
+import Control.Monad.Catch
+import Control.Monad.Logger hiding (Loc)
+import Control.Monad.IO.Class
+import Data.Aeson
+import Data.Text (Text)
+import qualified Data.Text as Text
+import Data.Typeable
+import qualified Data.Yaml as Yaml
 
-module Stackage.Config where
+import Filesystem.Loc
 
-data Config
+data Config =
+  Config {configPkgDbLocation :: Loc Absolute Dir
+         ,configSandboxLocation :: Loc Absolute Dir
+         ,configGhcBinLocation :: Loc Absolute Dir
+         ,configCabalBinLocation :: Loc Absolute Dir
+         ,configInDocker :: Bool
+         }
+data Settings = Settings
+
+data NotYetImplemented = NotYetImplemented Text
+  deriving (Show, Typeable)
+instance Exception NotYetImplemented
+
+
+-- Some examples of stackage.config
+
+-- (example 1)
+-- docker: true
+
+-- (example 2)
+-- cabal-sandbox:
+--   lts: 2
+
+-- (example 3)
+-- cabal-sandbox:
+--   nightly: 2015-06-01
+
+-- (example 4)
+-- cabal-sandbox:
+--   custom:
+--     ghc: /home/dan/ghc/ghc-6.12/bin
+--     cabal: /home/dan/.cabal/bin
+--     sandbox: .cabal-sandbox
+
+-- (example 5)
+-- cabal-sandbox:
+--   custom:
+--     ghc: '7.10'
+--     cabal: detect
+--     sandbox: detect
+
+data StackageConfig =
+  StackageConfig
+    { configStackageRoot :: Maybe Text
+    , configStackageHost :: Maybe Text
+    , configBuildStrategy :: BuildStrategy
+    }
+  deriving Show
+
+data BuildStrategy
+  = CabalSandbox CabalSandboxBuildStrategy
+  | Docker DockerBuildStrategy
+  deriving Show
+
+data CabalSandboxBuildStrategy
+  = BuildAgainstLTS LTSBuildStrategy
+  | BuildAgainstNightly NightlyBuildStrategy
+  | BuildAgainstSnapshot SnapshotBuildStrategy
+  | BuildAgainstCustom (CustomBuildStrategy Text)
+  deriving Show
+
+data DockerBuildStrategy =
+  DockerBuildStrategy
+  deriving Show
+
+data LTSBuildStrategy =
+  LTSBuildStrategy
+    { configLTS :: Text
+    }
+  deriving Show
+
+data NightlyBuildStrategy =
+  NightlyBuildStrategy
+    { configNightly :: Text
+    }
+  deriving Show
+
+data SnapshotBuildStrategy =
+  SnapshotBuildStrategy
+    { configSnapshot :: Text
+    }
+  deriving Show
+
+data CustomBuildStrategy a =
+  CustomBuildStrategy
+  { customGhcBinLocation :: a
+  , customCabalBinLocation :: a
+  , customSandboxLocation :: a
+  }
+  deriving Show
+
+
+instance FromJSON LTSBuildStrategy where
+  parseJSON j = parseAsText j <|> parseAsScientific j where
+    parseAsText = withText "LTSBuildStrategy" $ \t -> do
+      let configLTS = t
+      return LTSBuildStrategy{..}
+    -- allows people to not have to quote the lts field
+    parseAsScientific = withScientific "LTSBuildStrategy" $ \s -> do
+      let configLTS = Text.pack $ show s
+      return LTSBuildStrategy{..}
+
+instance FromJSON NightlyBuildStrategy where
+  parseJSON = withText "NightlyBuildStrategy" $ \t -> do
+    let configNightly = t
+    return NightlyBuildStrategy{..}
+
+instance FromJSON SnapshotBuildStrategy where
+  parseJSON = withText "SnapshotBuildStrategy" $ \t -> do
+    let configSnapshot = t
+    return SnapshotBuildStrategy{..}
+
+
+instance FromJSON a => FromJSON (CustomBuildStrategy a) where
+  parseJSON = withObject "CustomBuildStrategy" $ \obj -> do
+    customGhcBinLocation <- obj .: "ghc"
+    customCabalBinLocation <- obj .: "cabal"
+    customSandboxLocation <- obj .: "sandbox"
+    return CustomBuildStrategy{..}
+
+instance FromJSON StackageConfig where
+  parseJSON = withObject "StackageConfig" $ \obj -> do
+    configStackageRoot <- obj .:? "stackage-root" 
+    configStackageHost <- obj .:? "stackage-host"
+    configBuildStrategy <-
+      (Docker <$> obj .: "docker") <|>
+      (CabalSandbox <$> obj .: "cabal-sandbox")
+    return StackageConfig{..}
+
+instance FromJSON DockerBuildStrategy where
+  parseJSON = withBool "DockerBuildStrategy" $ \b ->
+    if b
+      then return DockerBuildStrategy
+      else fail "docker: false"
+
+instance FromJSON CabalSandboxBuildStrategy where
+  parseJSON = withObject "CabalSandboxBuildStrategy" $ \obj ->
+    (BuildAgainstLTS <$> obj .: "lts") <|>
+    (BuildAgainstNightly <$> obj .: "nightly") <|>
+    (BuildAgainstSnapshot <$> obj .: "snapshot") <|>
+    (BuildAgainstCustom <$> obj .: "custom")
+
+parseBuildStrategy :: (MonadLogger m, MonadIO m, MonadThrow m)
+  => CabalSandboxBuildStrategy -> m (CustomBuildStrategy (Loc Absolute Dir))
+parseBuildStrategy (BuildAgainstLTS lts) =
+  resolveLTSSnapshot lts >>= parseBuildStrategy . BuildAgainstSnapshot
+parseBuildStrategy (BuildAgainstNightly nightly) =
+  resolveNightlySnapshot nightly >>= parseBuildStrategy . BuildAgainstSnapshot
+parseBuildStrategy (BuildAgainstSnapshot snapshot) = do
+  customGhcBinLocation <- resolveSnapshotGhcLoc snapshot
+  customCabalBinLocation <- resolveSnapshotCabalLoc snapshot
+  customSandboxLocation <- resolveSnapshotSandboxLoc snapshot
+  return CustomBuildStrategy{..}
+parseBuildStrategy (BuildAgainstCustom custom) = do
+  ghcBinLoc <- resolveCustomGhcLoc (customGhcBinLocation custom)
+  cabalBinLoc <- resolveCustomCabalLoc (customCabalBinLocation custom)
+  sandboxLocation <- resolveCustomSandboxLoc (customSandboxLocation custom)
+  return CustomBuildStrategy
+    { customGhcBinLocation = ghcBinLoc
+    , customCabalBinLocation = cabalBinLoc
+    , customSandboxLocation = sandboxLocation
+    }
+
+-- TODO
+-- Build strategy based on whatever ghc, cabal, and sandbox are visible.
+--defaultBuildStrategy :: (MonadLogger m, MonadIO m, MonadThrow m)
+--  => m (CustomBuildStrategy (Loc Absolute Dir))
+--defaultBuildStrategy = undefined
+
+getStackageConfig :: (MonadLogger m, MonadIO m, MonadThrow m)
+  => m StackageConfig
+getStackageConfig = do
+  mconf <- liftIO $ Yaml.decodeFile "stackage.config"
+  maybe (throwM $ NotYetImplemented "getStackageConfig") return mconf
+
+
+configFromStackageConfig :: (MonadLogger m, MonadIO m, MonadThrow m)
+  => StackageConfig -> m Config
+configFromStackageConfig StackageConfig{..} = do
+  CustomBuildStrategy{..} <- case configBuildStrategy of
+    CabalSandbox strategy -> parseBuildStrategy strategy
+    Docker _ -> throwM $ NotYetImplemented "configFromStackageConfig"
+  let configPkgDbLocation = undefined
+      configSandboxLocation = undefined
+      configGhcBinLocation = undefined
+      configCabalBinLocation = undefined
+      configInDocker = undefined
+  return Config{..}
+
+-- TODO: handle more settings
+-- TODO: handle failure to retrieve StacakgeConfig
+getConfig :: (MonadLogger m,MonadIO m,MonadThrow m)
+          => Settings -> m Config
+getConfig Settings = do
+  stackageConfig <- getStackageConfig
+  configFromStackageConfig stackageConfig
+
+
+resolveLTSSnapshot :: (MonadLogger m, MonadIO m, MonadThrow m)
+  => LTSBuildStrategy -> m SnapshotBuildStrategy
+resolveLTSSnapshot _ = throwM $ NotYetImplemented "resolveLTSSnapshot"
+
+resolveNightlySnapshot :: (MonadLogger m, MonadIO m, MonadThrow m)
+  => NightlyBuildStrategy -> m SnapshotBuildStrategy
+resolveNightlySnapshot _ = throwM $ NotYetImplemented "resolveNightlySnapshot"
+
+
+resolveSnapshotSandboxLoc :: (MonadLogger m, MonadIO m, MonadThrow m)
+  => SnapshotBuildStrategy -> m (Loc Absolute Dir)
+resolveSnapshotSandboxLoc _ = throwM $ NotYetImplemented "resolveSnapshotSandboxLoc"
+
+resolveSnapshotGhcLoc :: (MonadLogger m, MonadIO m, MonadThrow m)
+  => SnapshotBuildStrategy -> m (Loc Absolute Dir)
+resolveSnapshotGhcLoc _ = throwM $ NotYetImplemented "resolveSnapshotGhcLoc"
+
+resolveSnapshotCabalLoc :: (MonadLogger m, MonadIO m, MonadThrow m)
+  => SnapshotBuildStrategy -> m (Loc Absolute Dir)
+resolveSnapshotCabalLoc _ = throwM $ NotYetImplemented "resolveSnapshotCabalLoc"
+
+resolveCustomSandboxLoc :: (MonadLogger m, MonadIO m, MonadThrow m)
+  => Text -> m (Loc Absolute Dir)
+resolveCustomSandboxLoc _ = throwM $ NotYetImplemented "resolveCustomSandboxLoc"
+
+resolveCustomGhcLoc :: (MonadLogger m, MonadIO m, MonadThrow m)
+  => Text -> m (Loc Absolute Dir)
+resolveCustomGhcLoc _ = throwM $ NotYetImplemented "resolveCustomGhcLoc"
+
+resolveCustomCabalLoc :: (MonadLogger m, MonadIO m, MonadThrow m)
+  => Text -> m (Loc Absolute Dir)
+resolveCustomCabalLoc _ = throwM $ NotYetImplemented "resolveCustomCabalLoc"
diff --git a/src/Stackage/Environment.hs b/src/Stackage/Environment.hs
new file mode 100644
index 00000000..16df71bd
--- /dev/null
+++ b/src/Stackage/Environment.hs
@@ -0,0 +1,24 @@
+-- | Handling of environment variables, such as the PATH,
+-- GHC_PACKAGE_SANDBOX, etc.
+module Stackage.Environment where
+
+import Control.Monad.Catch
+import Control.Monad.Logger hiding (Loc)
+import Control.Monad.IO.Class
+import Data.Map (Map)
+import Data.Text (Text)
+
+import Stackage.Config
+
+
+getEnvironmentVariables :: (MonadLogger m,MonadIO m,MonadThrow m)
+                        => Config -> m (Map Text Text)
+getEnvironmentVariables _ = throwM $ NotYetImplemented "getEnvironmentVariables"
+
+getPATH :: (MonadLogger m,MonadIO m,MonadThrow m)
+        => Config -> m Text
+getPATH _ = throwM $ NotYetImplemented "getPATH"
+
+withConfiguredEnvironment :: (MonadLogger m,MonadIO m,MonadThrow m)
+                          => Config -> (m a -> m a) -> m a
+withConfiguredEnvironment _ _ = throwM $ NotYetImplemented "withConfiguredEnvironment"
diff --git a/stackage-common.cabal b/stackage-common.cabal
index 468eb241..749294fa 100644
--- a/stackage-common.cabal
+++ b/stackage-common.cabal
@@ -14,7 +14,13 @@ cabal-version:       >=1.8
 library
   hs-source-dirs:    src/
   ghc-options:       -Wall -O2
+  extensions:        DeriveDataTypeable
+                     RecordWildCards
+                     DataKinds
+                     OverloadedStrings
   exposed-modules:   Stackage.Types
+                     Stackage.Config
+                     Stackage.Environment
                      Stackage.GhcPkg
                      Stackage.GhcPkgId
                      Stackage.PackageName