Merge pull request #283 from zoominsoftware/feat/healthcheck-endpoint

Add config "healthcheck-path" to respond 200 on

ChangeLog.md

@@ -1,5 +1,7 @@
 ## 2.1.3
 
+* Add `healthcheck-path` global config for Keter-only healthchecks. PR #283
+
 * Fix config keys `unknown-host-response-file` and `missing-host-response-file`
   accidentally flipped. PR #282
 * In case reading any one of `*-host-response-file` fails, keter now logs a warning,

etc/keter-config.yaml

@@ -21,14 +21,15 @@ listeners:
       session: true
 
 # User to run applications as
-
 # setuid: ubuntu
 
 # Get the user's IP address from x-forwarded-for. Useful when sitting behind a
 # load balancer like Amazon ELB.
-
 # ip-from-header: true
 
+# If set, this path will respond 200 OK to requests on any vhost
+# healthcheck-path: /keter-health
+
 # Control the port numbers assigned via APPROOT
 # external-http-port: 8080
 # external-https-port: 450

keter.cabal

@@ -114,6 +114,7 @@ library
     Keter.Yaml.FilePath
 
   other-modules:    Keter.Aeson.KeyHelper
+                    Paths_keter
   ghc-options:      -Wall
   c-sources:        cbits/process-tracker.c
   hs-source-dirs:   src

src/Keter/Config/V10.hs

@@ -114,6 +114,7 @@ data KeterConfig = KeterConfig
     , kconfigProxyException       :: !(Maybe F.FilePath)
 
     , kconfigRotateLogs           :: !Bool
+    , kconfigHealthcheckPath      :: !(Maybe Text)
     }
 
 instance ToCurrent KeterConfig where
@@ -134,6 +135,7 @@ instance ToCurrent KeterConfig where
         , kconfigMissingHostResponse = Nothing
         , kconfigProxyException = Nothing
         , kconfigRotateLogs = True
+        , kconfigHealthcheckPath = Nothing
         }
       where
         getSSL Nothing = V.empty
@@ -162,6 +164,7 @@ defaultKeterConfig = KeterConfig
         , kconfigMissingHostResponse = Nothing
         , kconfigProxyException = Nothing
         , kconfigRotateLogs = True
+        , kconfigHealthcheckPath = Nothing
         }
 
 instance ParseYamlFile KeterConfig where
@@ -187,6 +190,7 @@ instance ParseYamlFile KeterConfig where
             <*> o .:? "missing-host-response-file"
             <*> o .:? "proxy-exception-response-file"
             <*> o .:? "rotate-logs" .!= True
+            <*> o .:? "app-crash-hook"
 
 -- | Whether we should force redirect to HTTPS routes.
 type RequiresSecure = Bool
@@ -317,7 +321,7 @@ instance ToCurrent RedirectConfig where
 
 instance ParseYamlFile RedirectConfig where
     parseYamlFile _ = withObject "RedirectConfig" $ \o -> RedirectConfig
-        <$> (Set.map CI.mk <$> ((o .: "hosts" <|> (Set.singleton <$> (o .: "host")))))
+        <$> (Set.map CI.mk <$> (o .: "hosts" <|> Set.singleton <$> o .: "host"))
         <*> o .:? "status" .!= 303
         <*> o .: "actions"
         <*> o .:? "ssl" .!= SSLFalse

src/Keter/Proxy.hs

@@ -60,6 +60,7 @@ import           System.FilePath            (FilePath)
 import           Control.Monad.Logger
 import           Control.Exception          (SomeException)
 import           Network.HTTP.Types                (mkStatus,
+                                                    status200,
                                                     status301, status302,
                                                     status303, status307,
                                                     status404, status502)
@@ -76,6 +77,9 @@ import qualified Network.TLS as TLS
 import qualified System.Directory as Dir
 import Keter.Context
 
+import           Data.Version (showVersion)
+import qualified Paths_keter as Pkg
+
 #if !MIN_VERSION_http_reverse_proxy(0,6,0)
 defaultWaiProxySettings = def
 #endif
@@ -91,6 +95,7 @@ data ProxySettings = MkProxySettings
   , psManager        :: !Manager
   , psIpFromHeader   :: Bool
   , psConnectionTimeBound :: Int
+  , psHealthcheckPath :: !(Maybe ByteString)
   , psUnknownHost    :: ByteString -> ByteString
   , psMissingHost    :: ByteString
   , psProxyException :: ByteString
@@ -107,6 +112,7 @@ makeSettings hostman = do
     -- configuration option is in milliseconds
     let psConnectionTimeBound = kconfigConnectionTimeBound * 1000
     let psIpFromHeader = kconfigIpFromHeader
+    let psHealthcheckPath = encodeUtf8 <$> kconfigHealthcheckPath
     pure $ MkProxySettings{..}
     where
         psHostLookup = HostMan.lookupAction hostman . CI.mk
@@ -178,6 +184,10 @@ withClient isSecure = do
 
 
     getDest :: ProxySettings -> Wai.Request -> IO (LocalWaiProxySettings, WaiProxyResponse)
+    -- respond to healthckecks, regardless of Host header value and presence
+    getDest MkProxySettings{..} req | psHealthcheckPath == Just (Wai.rawPathInfo req)
+      = return (defaultLocalWaiProxySettings, WPRResponse healthcheckResponse)
+    -- inspect Host header to determine which App to proxy to
     getDest cfg@MkProxySettings{..} req =
         case Wai.requestHeaderHost req of
             Nothing -> do
@@ -303,6 +313,13 @@ handleProxyException handleException onexceptBody except req respond = do
   handleException req except
   respond $ missingHostResponse onexceptBody
 
+healthcheckResponse :: Wai.Response
+healthcheckResponse = Wai.responseBuilder
+    status200
+    [("Content-Type", "text/plain; charset=utf-8")]
+    $ "Keter " <> (copyByteString . S8.pack . showVersion) Pkg.version
+               <> " is doing okay!\n"
+
 defaultProxyException :: ByteString
 defaultProxyException = "<!DOCTYPE html>\n<html><head><title>Welcome to Keter</title></head><body><h1>Welcome to Keter</h1><p>There was a proxy error, check the keter logs for details.</p></body></html>"
 

test/Spec.hs

@@ -98,4 +98,5 @@ headThenPostNoCrash = do
       , psProxyException = ""
       , psIpFromHeader   = False
       , psConnectionTimeBound = 5 * 60 * 1000
+      , psHealthcheckPath = Nothing
       }