How to Add Prometheus Metrics to Open API Mux in Golang

Yo buddy,

So, guess what? You wanna add Prometheus metrics to your Open API Mux in Golang. Umm, sounds like a wild party, right? Imagine a bunch of metrics dancing around telling you what’s happening in your app while you chill and sip some lemonade. Sounds fun, huh? Let’s dive into this whimsical adventure together.

Let’s get started with the seven steps to make it happen. Ready? Here we go!

Step One: Install the Go Client for Prometheus

First thing first, We gotta grab that shiny Go client for Prometheus. It’s like bringing snacks to a party – it just makes everything better, right? So fire up your terminal and type `go get github.com/prometheus/client_golang/prometheus`.

Boom! You got it! Now your app can talk to Prometheus like best buds.

Step Two: Create Your Metrics

Now it’s time to create some metrics. You can think of them as your app’s Twitter updates. “Hey world! I just processed another request!” So in your code, you wanna say something like:

“`go
var (
requestCount = prometheus.NewCounterVec(prometheus.CounterOpts{
Name: “http_requests_total”,
Help: “Total number of HTTP requests.”,
}, []string{“method”, “endpoint”})
)
“`

And don’t forget to register them with:

“`go
prometheus.MustRegister(requestCount)
“`

Your code is now ready to spill the beans about how many requests it’s handling.

Step Three: Set Up Your HTTP Handler

Alrighty then, time to set up an HTTP handler that knows how to deal with those fancy metrics. It’s basically telling the server, “Hey dude, when someone asks for /metrics, show ‘em what we got!” Look here:

“`go
http.Handle(“/metrics”, promhttp.Handler())
“`

That way when Prometheus comes knocking on your door like “Yo let me see those metrics,” it’ll be able to check ‘em out.

Step Four: Initialize Your Mux Router

Mux is like the bouncer at the bar making sure only the cool kids get in. So, you’ve got this cool router thing going on; let’s set that up real easy peasy:

“`go
r := mux.NewRouter()
“`

Then slap on some routes ’cause what’s a party without guests?

Step Five: Add Middleware for Metrics

We all love middleware—but not that kind where they serve bad pizza at meetings. This is cooler! You should create some middleware that records when requests come in.

Here’s a fun example:

“`go
func metricsMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Count requests
requestCount.WithLabelValues(r.Method, r.URL.Path).Inc()

next.ServeHTTP(w, r) // Let’s pass it along
})
}
“`

Now every time someone walks in through our router door, we count them!

Step Six: Hook It All Up

Put everything together now. I mean like a huge traffic jam of code coming together into sweet harmony. Your main function should look something like this:

“`go
func main() {
r := mux.NewRouter()

r.Use(metricsMiddleware)

r.Handle(“/metrics”, promhttp.Handler())

log.Fatal(http.ListenAndServe(“:8080”, r))
}
“`

Bam! Just hit run and watch those metrics fluff around all happy-like.

Step Seven: Celebrate With A Browser Visit

You did it! Now let’s see if Prometheus is working its magic by visiting `http://localhost:8080/metrics`. If everything went well—like a perfectly executed high five—you’ll see all those lovely numbers and stats parading around!

Okay now before I send you off into coding bliss, let’s tackle some FAQ madness.

Question: What even are Prometheus metrics?
Answer: Think of them as little notes about how your program is doing; they tell everyone what’s happening behind the scenes so you can keep track.

Question: Do I need an actual PhD to understand these metrics?
Answer: Nah man! If you can order pizza on the phone, you’re golden!

Question: Can I add more metrics later?
Answer: Absolutely! It’s kinda like adding toppings onto a pizza; just do what feels right!

Question: What if my app crashes while I’m doing this?
Answer: That happens even when you’re trying to tie shoelaces sometimes! Just stay calm and fix it like a pro!

Question: Is there a max number of requests my app can handle?
Answer: Well it’s not a reality TV show; depends on hardware but usually you’ll surprise yourself!

Question: What if I have no idea what’s happening half the time?
Answer: Welcome to coding life! You’re not alone in that boat buddy!

Question: Can I throw confetti when my metrics work?
Answer: Of course! Confetti makes everything better—just don’t let it mess up your keyboard ok?

And there ya go pal! You’ve added Prometheous metrics and became one step closer to being the coolest coder ever. Now go out there and make those numbers dance!