func NewHealthController(startTime time.Time, commit string, roshiURI string) Controller {
	return &healthController{
		startTime: startTime,
		commit:    commit,
		roshi:     roshiURI,
	}
}
NewHealthController returns a controller that will display metrics to /metrics
package api
import (
	"bytes"
	"net/http"
	"time"
	log "github.com/Sirupsen/logrus"
	"github.com/julienschmidt/httprouter"
	metrics "github.com/rcrowley/go-metrics"
)
type healthController struct {
	baseController
	startTime time.Time
	commit    string
	roshi     string
}
type heartbeatResponse struct {
	Commit string `json:"commit"`
	Uptime string `json:"uptime"`
}