{-# LANGUAGE TemplateHaskell #-} ----------------------------------------------------------------------------- -- | -- Module : NgxExport.Tools.ServiceHookAdaptor -- Copyright : (c) Alexey Radkov 2021 -- License : BSD-style -- -- Maintainer : alexey.radkov@gmail.com -- Stability : experimental -- Portability : non-portable (requires Template Haskell) -- -- A service hook adaptor from the more extra tools collection for -- <http://github.com/lyokha/nginx-haskell-module nginx-haskell-module>. -- ----------------------------------------------------------------------------- module NgxExport.Tools.ServiceHookAdaptor ( -- * Maintaining custom global data in run-time -- $maintainingCustomGlobalData ) where import NgxExport.Tools import Data.ByteString (ByteString) import qualified Data.ByteString.Lazy as L import Control.Monad -- $maintainingCustomGlobalData -- -- This module exports a /simple service/ (in terms of module "NgxExport.Tools") -- __/simpleService_hookAdaptor/__ which sleeps forever. Its sole purpose is to -- serve /service hooks/ for changing global data in all the worker processes in -- run-time. A single service hook adaptor can serve any number of service hooks -- with any type of global data. -- -- Below is a simple example. -- -- ==== File /test_tools_extra_servicehookadaptor.hs/ -- @ -- {-\# LANGUAGE TemplateHaskell, OverloadedStrings \#-} -- -- module TestToolsExtraServiceHookAdaptor where -- -- import NgxExport -- import NgxExport.Tools.ServiceHookAdaptor () -- -- import Data.ByteString (ByteString) -- import qualified Data.ByteString as B -- import qualified Data.ByteString.Lazy as L -- import Data.IORef -- import System.IO.Unsafe -- -- secretWord :: IORef ByteString -- secretWord = unsafePerformIO $ newIORef "" -- {-\# NOINLINE secretWord \#-} -- -- testSecretWord :: ByteString -> IO L.ByteString -- __/testSecretWord/__ v = do -- s <- readIORef secretWord -- return $ if B.null s -- then \"null\" -- else if v == s -- then \"set\" -- else \"unset\" -- 'NgxExport.ngxExportIOYY' 'testSecretWord -- -- changeSecretWord :: ByteString -> IO L.ByteString -- __/changeSecretWord/__ s = do -- writeIORef secretWord s -- return \"The secret word was changed\" -- 'NgxExport.ngxExportServiceHook' \'changeSecretWord -- @ -- -- Here we are going to maintain a /secret word/ of type 'ByteString' in -- run-time. When a worker process starts, the word is empty. The word can be -- changed in run-time by triggering service hook /changeSecretWord/. Client -- requests are managed differently depending on their knowledge of the secret -- which is tested in handler /testSecretWord/. -- -- ==== File /nginx.conf/ -- @ -- user nobody; -- worker_processes 2; -- -- events { -- worker_connections 1024; -- } -- -- error_log \/tmp\/nginx-test-haskell-error.log info; -- -- http { -- default_type application\/octet-stream; -- sendfile on; -- error_log \/tmp\/nginx-test-haskell-error.log; -- access_log \/tmp\/nginx-test-haskell-access.log; -- -- haskell load \/var\/lib\/nginx\/test_tools_extra_servicehookadaptor.so; -- -- haskell_run_service __/simpleService_hookAdaptor/__ $hs_hook_adaptor \'\'; -- -- haskell_service_hooks_zone hooks 32k; -- -- server { -- listen 8010; -- server_name main; -- -- location \/ { -- haskell_run __/testSecretWord/__ $hs_secret_word $arg_s; -- -- if ($hs_secret_word = null) { -- echo_status 503; -- echo \"Try later! The service is not ready!\"; -- break; -- } -- -- if ($hs_secret_word = set) { -- echo_status 200; -- echo \"Congrats! You know the secret word!\"; -- break; -- } -- -- echo_status 404; -- echo \"Hmm, you do not know a secret!\"; -- } -- -- location \/change_sw { -- allow 127.0.0.1; -- deny all; -- -- haskell_service_hook __/changeSecretWord/__ $hs_hook_adaptor $arg_s; -- } -- } -- } -- @ -- -- Notice that service /simpleService_hookAdaptor/ is not shared, however this -- is not such important because shared services must work as well. -- -- ==== A simple test -- After starting Nginx, the secret word service must be not ready. -- -- > $ curl 'http://127.0.0.1:8010/' -- > Try later! The service is not ready! -- -- Let's change the secret word, -- -- > $ curl 'http://127.0.0.1:8010/change_sw?s=secret' -- -- and try again. -- -- > $ curl 'http://127.0.0.1:8010/' -- > Hmm, you do not know a secret! -- > $ curl 'http://127.0.0.1:8010/?s=try1' -- > Hmm, you do not know a secret! -- > $ curl 'http://127.0.0.1:8010/?s=secret' -- > Congrats! You know the secret word! -- -- Change the secret word again. -- -- > $ curl 'http://127.0.0.1:8010/change_sw?s=secret1' -- > $ curl 'http://127.0.0.1:8010/?s=secret' -- > Hmm, you do not know a secret! -- > $ curl 'http://127.0.0.1:8010/?s=secret1' -- > Congrats! You know the secret word! -- -- What if a worker process quits for some reason or crashes? Let's try! -- -- > # ps -ef | grep nginx | grep worker -- > nobody 13869 13868 0 15:43 ? 00:00:00 nginx: worker process -- > nobody 13870 13868 0 15:43 ? 00:00:00 nginx: worker process -- > # kill -QUIT 13869 13870 -- > # ps -ef | grep nginx | grep worker -- > nobody 14223 13868 4 15:56 ? 00:00:00 nginx: worker process -- > nobody 14224 13868 4 15:56 ? 00:00:00 nginx: worker process -- -- > $ curl 'http://127.0.0.1:8010/?s=secret1' -- > Congrats! You know the secret word! -- -- Our secret is still intact! This is because service hooks manage new worker -- processes so well as those that were running when a hook was triggered. hookAdaptor :: ByteString -> Bool -> IO L.ByteString hookAdaptor :: ByteString -> Bool -> IO ByteString hookAdaptor = (ByteString -> IO ByteString) -> ByteString -> Bool -> IO ByteString forall a. (a -> IO ByteString) -> a -> Bool -> IO ByteString ignitionService ((ByteString -> IO ByteString) -> ByteString -> Bool -> IO ByteString) -> (ByteString -> IO ByteString) -> ByteString -> Bool -> IO ByteString forall a b. (a -> b) -> a -> b $ IO ByteString -> ByteString -> IO ByteString forall a b. a -> b -> a const (IO ByteString -> ByteString -> IO ByteString) -> IO ByteString -> ByteString -> IO ByteString forall a b. (a -> b) -> a -> b $ IO () -> IO ByteString forall (f :: * -> *) a b. Applicative f => f a -> f b forever (IO () -> IO ByteString) -> IO () -> IO ByteString forall a b. (a -> b) -> a -> b $ Int -> IO () threadDelaySec (Int -> IO ()) -> Int -> IO () forall a b. (a -> b) -> a -> b $ TimeInterval -> Int toSec (TimeInterval -> Int) -> TimeInterval -> Int forall a b. (a -> b) -> a -> b $ Int -> TimeInterval Hr 24 ngxExportSimpleService 'hookAdaptor SingleShotService