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Hooking up golang Revel with Newrelic



There is a go client for newrelic called GoRelic

So that's pretty easy to hookup with any go app.

However it was just a little bit trickier to hook up the Http metrics part with Revel.
That is because Revel does not really offer an way (AFAIK) to directly wrap the handler such as:
http.HandleFunc("/", agent.WrapHTTPHandlerFunc(handler))


Besides I want to monitor all requests, so anyway here is how I hook it up.

init.go of the revel app
package app

import (
  "log"
  "time"

  "github.com/robfig/revel"
  "github.com/yvasiyarov/go-metrics"
  "github.com/yvasiyarov/gorelic"
)

// Need to keep a variable for the gerelic agent
var agent *gorelic.Agent

func init() {

  initGorelic()

  revel.Filters = []revel.Filter{
    gorelicFilter, // We add a custom filter
   // ... all the other revel filters
  }

}

// initGorelic Initializes the Gorelic agent
func initGorelic() {

  // Note I load NEWRELIC_LICENSE from a  config file not shown here. Only start gorelic if a license id resent.
  if len(NEWRELIC_LICENSE) > 0 {
    log.Print("Starting newrelic daemon.")
    agent = gorelic.NewAgent()
    agent.NewrelicLicense = NEWRELIC_LICENSE
    agent.NewrelicName = "YourAppName"
    agent.NewrelicPollInterval = 180
    agent.Verbose = true

    // "Manually" init the http timer (will be used in gorelicFilter)
    agent.CollectHTTPStat = true
    agent.HTTPTimer = metrics.NewTimer()

    agent.Run()
  } else {
    log.Print("!! Newrelic license missing from config file -> Not started")
  }
}

// Filter to capture HTTP metrics for gorelic
var gorelicFilter = func(c *revel.Controller, fc []revel.Filter) {
  startTime := time.Now()
  defer func() {
    if agent != nil {
      agent.HTTPTimer.UpdateSince(startTime)
    }
  }()
  fc[0](c, fc[1:])
}


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