I would like to try simple example of using Prometheus.
I have started simple code, but with few modifications
var addr = flag.String("listen-address", ":8080", "The address to listen on for HTTP requests.")
func main() {
flag.Parse()
http.Handle("/metrics", promhttp.Handler())
http.Handle("/test/{id}", myHandler(promhttp.Handler()))
log.Fatal(http.ListenAndServe(*addr, nil))
}
func myHandler(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "hello, you've hit %s
", r.URL.Path)
next.ServeHTTP(w, r)
})
}
Questions:
metrics and /test/{id} separately. Did I get the idea correctly by creating several handlers and using promhttp.Handler() as middleware?To follow up on @David Maze's answer, the default handler promhttp.Handler is for reporting metrics. (gathers from all registered handlers and reports them on request).
Unfortunately, it is not a generic http middleware that gives you any metrics out of the box.
I have seen many of go's web frameworks have some sort of community prometheus middleware (gin's) that give metrics out of the box (latency, response code, request counts, etc).
The go prometheus client library has examples of how to add metrics to your application.
var (
httpRequests = prometheus.NewCounter(
prometheus.CounterOpts{
Name: "http_requests_total",
Help: "Number of http requests.",
},
)
)
func init() {
// Metrics have to be registered to be exposed:
prometheus.MustRegister(httpRequests)
}
func myHandler(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
httpRequests.Inc()
fmt.Fprintf(w, "hello, you've hit %s
", r.URL.Path)
next.ServeHTTP(w, r)
})
}
As for your second question lots :) Google advocates for monitoring 4 golden signals:
These are
In my experie8inces it has also been helpful to have visibility of all the interactions between your appl8ication and your database (ie the 4 golden signals applied to your database):