diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright IIJ Innovation Institute Inc. (c) 2020
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of IIJ Innovation Institute Inc. nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/README.md b/README.md
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--- /dev/null
+++ b/README.md
@@ -0,0 +1,1 @@
+# hedis-envy
diff --git a/Setup.hs b/Setup.hs
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--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/hedis-envy.cabal b/hedis-envy.cabal
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--- /dev/null
+++ b/hedis-envy.cabal
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+cabal-version:      2.2
+name:               hedis-envy
+version:            0.1.0.0
+description:        Provides FromEnv instance for ConnectInfo of hedis
+homepage:           https://github.com/igrep/hedis-envy#readme
+bug-reports:        https://github.com/igrep/hedis-envy/issues
+author:             IIJ Innovation Institute, Inc.
+maintainer:         yuji-yamamoto@iij.ad.jp
+copyright:          2020 IIJ Innovation Institute, Inc.
+license:            BSD-3-Clause
+license-file:       LICENSE
+build-type:         Simple
+category:           Database,System
+extra-source-files: README.md
+
+source-repository head
+  type: git
+  location: https://github.com/igrep/hedis-envy
+
+library
+  exposed-modules:
+    Database.Redis.Envy
+    Database.Redis.Envy.Instance
+  build-depends:
+    , base >=4.7 && <5
+    , hedis >= 0.12
+    , envy >= 2.0
+    , time
+    , scientific
+  default-language: Haskell2010
+  hs-source-dirs:  src
diff --git a/src/Database/Redis/Envy.hs b/src/Database/Redis/Envy.hs
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--- /dev/null
+++ b/src/Database/Redis/Envy.hs
@@ -0,0 +1,93 @@
+module Database.Redis.Envy
+  ( connectInfoFromEnv
+  , connectInfoFromEnvWithDefault
+  , parsePortId
+  ) where
+
+
+import           Data.Foldable   (asum)
+import           Data.Scientific (Scientific)
+import           Data.Time       (NominalDiffTime)
+import           Data.Typeable   (Typeable)
+import qualified Database.Redis  as R
+import           System.Envy     (Parser, Var, env, envMaybe, fromVar, toVar,
+                                  (.!=))
+import           Text.Read       (readMaybe)
+
+
+newtype ReadShowVar a = ReadShowVar { unReadShowVar :: a }
+
+instance (Typeable a, Show a, Read a) => Var (ReadShowVar a) where
+  toVar = show . unReadShowVar
+  fromVar = fmap ReadShowVar . readMaybe
+
+
+-- | Get 'R.ConnectInfo' from these environment variables:
+--
+-- * @REDIS_HOST@:            'R.connectHost'
+-- * @REDIS_PORT_ID@:         'R.connectPort'
+-- * @REDIS_AUTH@:            'R.connectAuth'
+-- * @REDIS_DATABASE_INDEX@:  'R.connectDatabase'
+-- * @REDIS_MAX_CONNECTIONS@: 'R.connectMaxConnections'
+-- * @REDIS_MAX_IDLE_TIME@:   'R.connectMaxIdleTime'
+-- * @REDIS_TIMEOUT@:         'R.connectTimeout'
+--
+-- The corresponding field of 'R.defaultConnectInfo' is used as the default value.
+--
+-- NOTE: 'R.connectTLSParams' is NOT supported.
+-- This is hard to express as environment variables.
+connectInfoFromEnv :: Parser R.ConnectInfo
+connectInfoFromEnv = connectInfoFromEnvWithDefault R.defaultConnectInfo
+
+-- | A variant of 'connectInfoFromEnv' which you can provide the
+-- default value by yourself.
+--
+-- This is necessary to implement the instance of 'Env.FromEnv' for
+-- 'R.ConnectInfo' correctly.
+connectInfoFromEnvWithDefault :: R.ConnectInfo -> Parser R.ConnectInfo
+connectInfoFromEnvWithDefault def = R.ConnInfo
+  <$> envMaybe "REDIS_HOST" .!= R.connectHost def
+  <*> pPortId
+  <*> env "REDIS_AUTH" .!= R.connectAuth def
+  <*> envMaybe "REDIS_DATABASE_INDEX" .!= R.connectDatabase def
+  <*> envMaybe "REDIS_MAX_CONNECTIONS" .!= R.connectMaxConnections def
+  <*>
+    (fmap nominalDiffTimeFromVal <$> envMaybe "REDIS_MAX_IDLE_TIME")
+      .!= R.connectMaxIdleTime def
+  <*> timeout
+  <*> pure (R.connectTLSParams def)
+ where
+  nominalDiffTimeFromVal :: ReadShowVar Scientific -> NominalDiffTime
+  nominalDiffTimeFromVal = realToFrac . unReadShowVar
+
+  timeout :: Parser (Maybe NominalDiffTime)
+  timeout =
+    maybe
+      (R.connectTimeout def)
+      (Just . nominalDiffTimeFromVal)
+      <$> envMaybe "REDIS_TIMEOUT"
+
+  pPortId =
+    maybe
+      (pure (R.connectPort def))
+      parsePortId
+      =<< envMaybe "REDIS_PORT_ID"
+
+
+-- | Parse the value of @REDIS_PORT_ID@.
+-- The value must be a port number or the absolute path to the UNIX domain
+-- socket.
+--
+-- Internally used by 'connectInfoFromEnv'
+parsePortId
+  :: String -- ^ Value of environment variable
+  -> Parser R.PortID
+parsePortId envVarVal = maybe (fail emsg) pure $ asum
+  [ R.PortNumber <$> readMaybe envVarVal
+  , R.UnixSocket <$> parsePath envVarVal
+  ]
+ where
+  parsePath path@('/': _) = Just path
+  parsePath _other        = Nothing
+  emsg =
+    "The value of PortID must be a number (TCP port), or an absolute path to the UNIX domain socket!"
diff --git a/src/Database/Redis/Envy/Instance.hs b/src/Database/Redis/Envy/Instance.hs
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--- /dev/null
+++ b/src/Database/Redis/Envy/Instance.hs
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+{-# OPTIONS_GHC -Wno-orphans #-}
+
+module Database.Redis.Envy.Instance () where
+
+
+import qualified Database.Redis      as R
+import           Database.Redis.Envy
+import           System.Envy         (FromEnv, fromEnv)
+
+
+instance FromEnv R.ConnectInfo where
+  fromEnv Nothing    = connectInfoFromEnv
+  fromEnv (Just def) = connectInfoFromEnvWithDefault def