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servant-ekg
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Update to work with LTS-12.x and Servant 0.14

This commit is contained in:
Jesse Kempf 2019-02-11 11:58:45 -08:00 committed by Oleg Grenrus
parent 4a280658d9
commit 9c5a6ce1a3
6 changed files with 92 additions and 29 deletions
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14
.travis.yml
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@ -1,6 +1,6 @@
# This Travis job script has been generated by a script via
#
# haskell-ci '--output=.travis.yml' '--branches=master' 'cabal.project'
# haskell-ci '--output=.travis.yml' '--config=cabal.haskell-ci' 'cabal.project'
#
# For more information, see https://github.com/haskell-CI/haskell-ci
#
@ -115,5 +115,15 @@ script:
# Build without installed constraints for packages in global-db
- rm -f cabal.project.local; ${CABAL} new-build -w ${HC} --disable-tests --disable-benchmarks all;
# REGENDATA ["--output=.travis.yml","--branches=master","cabal.project"]
# Constraint sets
- rm -rf cabal.project.local
# Constraint set servant-0.15
- ${CABAL} new-build -w ${HC} --disable-tests --disable-benchmarks --constraint='servant ==0.15.*' all
# Constraint set servant-0.16
- ${CABAL} new-build -w ${HC} --disable-tests --disable-benchmarks --constraint='servant ==0.16.*' all
# REGENDATA ["--output=.travis.yml","--config=cabal.haskell-ci","cabal.project"]
# EOF

41
README.md Normal file
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@ -0,0 +1,41 @@
# servant-ekg
[![Build Status](https://travis-ci.org/haskell-servant/servant-ekg.png)](https://travis-ci.org/haskell-servant/servant-ekg)
# Servant Performance Counters
This package lets you track peformance counters for each of your Servant endpoints using EKG.
# Usage
Servant-EKG knows how to handle all official Servant combinators out of the box.
## Instrumenting your API
To use Servant-EKG, you'll need to wrap your WAI application with the Servant-EKG middleware.
```
import Network.Wai.Handler.Warp
import System.Metrics
import Servant.Ekg
wrapWithEkg :: Proxy api -> Server api -> IO Application
wrapWithEkg api server = do
store <- newStore
metrics <- newMVar mempty
return $ monitorEndpoints api store metrics (serve api server)
main :: IO ()
main = do
let api = ...
server = ...
app <- wrapWithEkg api server
run 8080 app
```
## Runtime overhead
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.
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.

9
cabal.haskell-ci Normal file
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@ -0,0 +1,9 @@
branches: master
constraint-set servant-0.15
ghc: >= 8.0 && <8.8
constraints: servant ==0.15.*
constraint-set servant-0.16
ghc: >= 8.0 && <8.8
constraints: servant ==0.16.*

13
lib/Servant/Ekg.hs
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@ -4,10 +4,10 @@
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE PolyKinds #-}
module Servant.Ekg where
import Control.Concurrent.MVar
@ -116,6 +116,7 @@ instance (KnownSymbol (path :: Symbol), HasEndpoint (sub :: *))
return (p:end, method)
_ -> Nothing
instance (KnownSymbol (capture :: Symbol), HasEndpoint (sub :: *))
=> HasEndpoint (Capture' mods capture a :> sub) where
getEndpoint _ req =
@ -147,8 +148,10 @@ instance HasEndpoint (sub :: *) => HasEndpoint (QueryFlag h :> sub) where
instance HasEndpoint (sub :: *) => HasEndpoint (ReqBody' mods cts a :> sub) where
getEndpoint _ = getEndpoint (Proxy :: Proxy sub)
#if MIN_VERSION_servant(0,15,0)
instance HasEndpoint (sub :: *) => HasEndpoint (StreamBody' mods framing ct a :> sub) where
getEndpoint _ = getEndpoint (Proxy :: Proxy sub)
#endif
instance HasEndpoint (sub :: *) => HasEndpoint (RemoteHost :> sub) where
getEndpoint _ = getEndpoint (Proxy :: Proxy sub)
@ -168,19 +171,17 @@ instance HasEndpoint (sub :: *) => HasEndpoint (WithNamedContext x y sub) where
instance ReflectMethod method => HasEndpoint (Verb method status cts a) where
getEndpoint _ req = case pathInfo req of
[] | requestMethod req == method -> Just ([], method)
_ -> Nothing
_ -> Nothing
where method = reflectMethod (Proxy :: Proxy method)
instance ReflectMethod method => HasEndpoint (Stream method status framing ct a) where
getEndpoint _ req = case pathInfo req of
[] | requestMethod req == method -> Just ([], method)
_ -> Nothing
_ -> Nothing
where method = reflectMethod (Proxy :: Proxy method)
instance HasEndpoint (Raw) where
instance HasEndpoint Raw where
getEndpoint _ _ = Just ([],"RAW")
#if MIN_VERSION_servant(0,8,1)
instance HasEndpoint (sub :: *) => HasEndpoint (CaptureAll (h :: Symbol) a :> sub) where
getEndpoint _ = getEndpoint (Proxy :: Proxy sub)
#endif

8
servant-ekg.cabal
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@ -1,6 +1,6 @@
cabal-version: >=1.10
name: servant-ekg
version: 0.2.1.0
version: 0.2.2.0
synopsis: Helpers for using ekg with servant
description: Helpers for using ekg with servant, e.g.. counters per endpoint.
license: BSD3
@ -24,13 +24,13 @@ library
hs-source-dirs: lib
build-depends:
base >=4.9 && <4.13
, ekg-core >=0.1.1.6 && <0.2
, ekg-core >=0.1.1.4 && <0.2
, http-types >=0.12.2 && <0.13
, servant >=0.15 && <0.17
, servant >=0.14 && <0.17
, text >=1.2.3.0 && <1.3
, time >=1.6.0.1 && <1.9
, unordered-containers >=0.2.9.0 && <0.3
, wai >=3.2.2 && <3.3
, wai >=3.2.0 && <3.3
default-language: Haskell2010

36
test/Servant/EkgSpec.hs
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@ -1,28 +1,34 @@
{-# LANGUAGE CPP #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
module Servant.EkgSpec (spec) where
import Control.Concurrent
import Data.Aeson
import Data.Monoid
import qualified Data.HashMap.Strict as H
import Data.Monoid ((<>))
import Data.Proxy
import qualified Data.HashMap.Strict as H
import Data.Text
import GHC.Generics
import Network.HTTP.Client (defaultManagerSettings, newManager)
import Network.HTTP.Client (defaultManagerSettings,
newManager)
import Network.Wai
import Network.Wai.Handler.Warp
import Servant
import Servant.Client
import Servant.Test.ComprehensiveAPI (comprehensiveAPI)
#if MIN_VERSION_servant(0,15,0)
import Servant.Test.ComprehensiveAPI (comprehensiveAPI)
#else
import Servant.API.Internal.Test.ComprehensiveAPI (comprehensiveAPI)
#endif
import System.Metrics
import qualified System.Metrics.Counter as Counter
import qualified System.Metrics.Counter as Counter
import Test.Hspec
import Servant.Ekg
@ -38,7 +44,7 @@ spec = describe "servant-ekg" $ do
let getEp :<|> postEp :<|> deleteEp = client testApi
it "collects number of request" $ do
it "collects number of request" $
withApp $ \port mvar -> do
mgr <- newManager defaultManagerSettings
let runFn :: ClientM a -> IO (Either ClientError a)
@ -101,11 +107,7 @@ server = helloH :<|> postGreetH :<|> deleteGreetH
postGreetH = return
#if MIN_VERSION_servant(0,8,0)
deleteGreetH _ = return NoContent
#else
deleteGreetH _ = return ()
#endif
-- Turn the server into a WAI app. 'serve' is provided by servant,
-- more precisely by the Servant.Server module.