From 2a5e07aeaf74deefb3985cb82ecf75347dc68ccd Mon Sep 17 00:00:00 2001
From: ynishinaka <96223955+ynishinaka@users.noreply.github.com>
Date: Fri, 10 Jan 2025 17:43:28 +0900
Subject: [PATCH 1/2] Support setting endpoints from environment variables

---
 lib/amazonka-core/src/Amazonka/Endpoint.hs | 37 ++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/lib/amazonka-core/src/Amazonka/Endpoint.hs b/lib/amazonka-core/src/Amazonka/Endpoint.hs
index e835befa513..20218d08399 100644
--- a/lib/amazonka-core/src/Amazonka/Endpoint.hs
+++ b/lib/amazonka-core/src/Amazonka/Endpoint.hs
@@ -9,13 +9,21 @@ module Amazonka.Endpoint
   ( -- * Endpoint
     setEndpoint,
     defaultEndpoint,
+    customEndpoints,
   )
 where
 
 import Amazonka.Data.ByteString
+import Amazonka.Data.Text (toText)
 import Amazonka.Prelude
 import Amazonka.Types
+import qualified Amazonka.Types as Service (Service (abbrev))
 import qualified Data.CaseInsensitive as CI
+import qualified Data.Char as Char
+import qualified Data.List as List
+import qualified Data.Text as Text
+import qualified Network.HTTP.Client as Client
+import qualified System.Environment as Environment
 
 -- | A convenience function for overriding the 'Service' 'Endpoint'.
 --
@@ -95,3 +103,32 @@ defaultEndpoint Service {endpointPrefix = p} r = go (CI.mk p)
         }
 
     reg = toBS r
+
+-- | Retrieve custom endpoints from environment variables:
+--
+-- * @AWS_ENDPOINT_URL@
+-- * @AWS_ENDPOINT_URL_<SERVICE>@
+--
+-- The latter takes precedence over the former.
+customEndpoints :: IO (Service -> Service)
+customEndpoints = do
+  environment <- Environment.getEnvironment
+  let globalUrl = lookup "AWS_ENDPOINT_URL" environment >>= Client.parseUrlThrow
+  let serviceUrls = mapMaybe (\(k, v) -> (,v) . map Char.toLower <$> removePrefix "AWS_ENDPOINT_URL_" k) environment
+  let override s =
+        case lookup (Text.unpack . Text.toLower . toText $ Service.abbrev s) serviceUrls of
+          Just x -> setEndpointMaybe (Client.parseUrlThrow x) s
+          Nothing -> setEndpointMaybe globalUrl s
+  pure override
+  where
+    removePrefix :: String -> String -> Maybe String
+    removePrefix prefix s =
+      if prefix `List.isPrefixOf` s
+        then Just $ drop (length prefix) s
+        else Nothing
+
+    setEndpointMaybe :: Maybe Client.Request -> Service -> Service
+    setEndpointMaybe mreq s =
+      case mreq of
+        Just req -> setEndpoint (Client.secure req) (Client.host req) (Client.port req) s
+        Nothing -> s

From 1900806f883489c387423253516c9262d8d73590 Mon Sep 17 00:00:00 2001
From: ynishinaka <96223955+ynishinaka@users.noreply.github.com>
Date: Fri, 10 Jan 2025 18:05:48 +0900
Subject: [PATCH 2/2] Use MonadIO instead of IO

---
 lib/amazonka-core/src/Amazonka/Endpoint.hs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/amazonka-core/src/Amazonka/Endpoint.hs b/lib/amazonka-core/src/Amazonka/Endpoint.hs
index 20218d08399..66780dfce2c 100644
--- a/lib/amazonka-core/src/Amazonka/Endpoint.hs
+++ b/lib/amazonka-core/src/Amazonka/Endpoint.hs
@@ -110,9 +110,9 @@ defaultEndpoint Service {endpointPrefix = p} r = go (CI.mk p)
 -- * @AWS_ENDPOINT_URL_<SERVICE>@
 --
 -- The latter takes precedence over the former.
-customEndpoints :: IO (Service -> Service)
+customEndpoints :: (MonadIO m) => m (Service -> Service)
 customEndpoints = do
-  environment <- Environment.getEnvironment
+  environment <- liftIO Environment.getEnvironment
   let globalUrl = lookup "AWS_ENDPOINT_URL" environment >>= Client.parseUrlThrow
   let serviceUrls = mapMaybe (\(k, v) -> (,v) . map Char.toLower <$> removePrefix "AWS_ENDPOINT_URL_" k) environment
   let override s =