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42 lines
1.4 KiB
Markdown
42 lines
1.4 KiB
Markdown
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# servant-ekg
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[](https://travis-ci.org/haskell-servant/servant-ekg)
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# Servant Performance Counters
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This package lets you track peformance counters for each of your Servant endpoints using EKG.
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# Usage
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Servant-EKG knows how to handle all official Servant combinators out of the box.
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## Instrumenting your API
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To use Servant-EKG, you'll need to wrap your WAI application with the Servant-EKG middleware.
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```
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import Network.Wai.Handler.Warp
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import System.Metrics
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import Servant.Ekg
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wrapWithEkg :: Proxy api -> Server api -> IO Application
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wrapWithEkg api server = do
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store <- newStore
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metrics <- newMVar mempty
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return $ monitorEndpoints api store metrics (serve api server)
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main :: IO ()
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main = do
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let api = ...
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server = ...
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app <- wrapWithEkg api server
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run 8080 app
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```
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## Runtime overhead
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Instrumenting your API introduces a non-zero runtime overhead, on the order of 200 - 600 µsec depending upon your machine. It's a good idea to run the benchmarks on your intended production platform to get an idea of how large the overhead will be. You'll need to have `wrk` installed to run the benchmarks.
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In general, the runtime overhead should be effectively negligible if your handlers are issuing network requests, such as to databases. If you have handlers that are small, CPU-only, and requested frequently, you will see a performance hit from Servant-EKG.
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