License	BSD3
Stability	experimental
Safe Haskell	None
Language	Haskell2010

Network.Wai.Metrics

Description

A WAI middleware to collect the following EKG metrics from compatible web servers:

number of requests (counter wai.request_count)
number of response by status code, broken down class (count wai.response_status_xxx)
latency distribution (distribution wai.latency_distribution)

Here's an example of reading these metrics from a Scotty server, and displaying them with EKG.

-- Compile with GHC option `-with-rtsopts=-T` for GC metrics
import Web.Scotty
import Control.Applicative
import System.Remote.Monitoring (serverMetricStore, forkServer)
import Network.Wai.Metrics

main :: IO()
main = do
  store <- serverMetricStore <$> forkServer "localhost" 8000
  waiMetrics <- registerWaiMetrics store
  scotty 3000 $ do
    middleware (metrics waiMetrics)
    get "/" $ html "Ping"

Now have a look at your local EKG instance and display the request count by clicking on 'wai.request_count'.

WAI metrics can also be stored in a bare EKG store, with no UI and no GC metrics. Use ekg-core's newStore function.

Compatible web servers include the following:

Yesod
Scotty
Spock
Servant
Warp

Synopsis

Documentation

registerWaiMetrics :: Store -> IO WaiMetrics Source

Register in EKG a number of metrics related to web server activity using empty namespace.

```
wai.request_count
```
```
wai.response_status_1xx
```
```
wai.response_status_2xx
```
```
wai.response_status_3xx
```
```
wai.response_status_4xx
```
```
wai.response_status_5xx
```
```
wai.latency_distribution
```

registerNamedWaiMetrics :: Text -> Store -> IO WaiMetrics Source

Register in EKG a number of metrics related to web server activity with a namespace.

```
namespace.wai.request_count
```
```
namespace.wai.response_status_1xx
```
```
namespace.wai.response_status_2xx
```
```
namespace.wai.response_status_3xx
```
```
namespace.wai.response_status_4xx
```
```
namespace.wai.response_status_5xx
```
```
namespace.wai.latency_distribution
```

data WaiMetrics Source

The metrics to feed in WAI and register in EKG.

Constructors

WaiMetrics
Fields requestCounter :: Counter latencyDistribution :: Distribution statusCode100Counter :: Counter statusCode200Counter :: Counter statusCode300Counter :: Counter statusCode400Counter :: Counter statusCode500Counter :: Counter

metrics :: WaiMetrics -> Middleware Source

Create a middleware to be added to a WAI-based webserver.