Bound authentication probe startup synchronization

test/Nuthatch/Probe/Curl.hs

@@ -1,5 +1,6 @@
 module Nuthatch.Probe.Curl
   ( CurlResponse (..)
+  , CurlTransportFailure (..)
   , cookieValue
   , curl
   , curlToFile
@@ -7,6 +8,7 @@ module Nuthatch.Probe.Curl
   , headerValues
   ) where
 
+import           Control.Exception (Exception, throwIO)
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.Char8 as B8
 import           Data.Char (toLower)
@@ -23,6 +25,13 @@ data CurlResponse = CurlResponse
   , curlBody    :: BS.ByteString
   } deriving stock (Eq, Show)
 
+data CurlTransportFailure = CurlTransportFailure
+  { curlTransportExitCode :: Int
+  , curlTransportStderr   :: String
+  } deriving stock (Eq, Show)
+
+instance Exception CurlTransportFailure
+
 curl :: [String] -> IO CurlResponse
 curl arguments =
   withSystemTempDirectory "nuthatch-curl" $ \directory -> do
@@ -56,12 +65,10 @@ runCurl outputPath arguments =
     case exitCode of
       ExitSuccess -> pure ()
       ExitFailure code ->
-        fail
-          ( "curl transport failed with exit "
-          <> show code
-          <> ": "
-          <> stderrText
-          )
+        throwIO CurlTransportFailure
+          { curlTransportExitCode = code
+          , curlTransportStderr = stderrText
+          }
     headers <- parseHeaders <$> BS.readFile headersPath
     pure CurlResponse
       { curlStatus = status