feat(api): create api proxy/ratelimiting/metrics

services/web-proxy/main.go

@@ -0,0 +1,127 @@
+package main
+
+import (
+	"context"
+	"log"
+	"net/http"
+	"net/http/httputil"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/go-redis/redis/v8"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+
+	"web-proxy/redis_rate"
+)
+
+var limiter *redis_rate.Limiter
+
+// todo: be able to raise ratelimits for >1 consumers
+var token2 string
+
+var remotes = map[string]*httputil.ReverseProxy{
+	"api.pluralkit.me":       proxyTo("[fdaa:0:ae33:a7b:8dd7:0:a:2]:8080"),
+	"dash.pluralkit.me":      proxyTo("[fdaa:0:ae33:a7b:8dd7:0:a:2]:8080"),
+	"sentry.pluralkit.me":    proxyTo("[fdaa:0:ae33:a7b:8dd7:0:a:202]:9000"),
+	"plausible.pluralkit.me": proxyTo("[fdaa:0:ae33:a7b:8dd7:0:a:202]:8000"),
+}
+
+func init() {
+	redisHost := requireEnv("REDIS_HOST")
+	redisPassword := requireEnv("REDIS_PASSWORD")
+
+	rdb := redis.NewClient(&redis.Options{
+		Addr:     redisHost,
+		Username: "default",
+		Password: redisPassword,
+	})
+	limiter = redis_rate.NewLimiter(rdb)
+
+	token2 = requireEnv("TOKEN2")
+
+	remotes["dash.pluralkit.me"].ModifyResponse = modifyDashResponse
+}
+
+type ProxyHandler struct{}
+
+func (p ProxyHandler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
+	remote, ok := remotes[r.Host]
+	if !ok {
+		// unknown domains redirect to landing page
+		http.Redirect(rw, r, "https://pluralkit.me", http.StatusFound)
+		return
+	}
+
+	if r.Host == "api.pluralkit.me" {
+		// root
+		if r.URL.Path == "" {
+			// api root path redirects to docs
+			http.Redirect(rw, r, "https://pluralkit.me/api/", http.StatusFound)
+			return
+		}
+
+		// CORS headers
+		rw.Header().Add("Access-Control-Allow-Origin", "*")
+		rw.Header().Add("Access-Control-Request-Method", r.Method)
+		rw.Header().Add("Access-Control-Allow-Credentials", "true")
+		rw.Header().Add("Access-Control-Allow-Headers", "Content-Type, Authorization, sentry-trace")
+		rw.Header().Add("Access-Control-Max-Age", "86400")
+
+		if r.Method == http.MethodOptions {
+			rw.WriteHeader(200)
+			return
+		}
+
+		if is_api_ratelimited(rw, r) {
+			return
+		}
+	}
+
+	startTime := time.Now()
+	r = r.WithContext(context.WithValue(r.Context(), "req-time", startTime))
+
+	remote.ServeHTTP(rw, r)
+}
+
+func logTimeElapsed(resp *http.Response) error {
+	r := resp.Request
+
+	startTime := r.Context().Value("req-time").(time.Time)
+
+	elapsed := time.Since(startTime)
+	metric.With(map[string]string{
+		"domain": r.Host,
+		"method": r.Method,
+		"status": strconv.Itoa(resp.StatusCode),
+		"route":  cleanPath(r.Host, r.URL.Path),
+	}).Observe(elapsed.Seconds())
+
+	log.Printf("[%s %s] \"%s %s%s\" %d - %vms\n", r.Header.Get("Fly-Client-IP"), r.Header.Get("User-Agent"), r.Method, r.Host, r.URL.Path, resp.StatusCode, elapsed.Milliseconds())
+
+	return nil
+}
+
+func modifyDashResponse(resp *http.Response) error {
+	r := resp.Request
+
+	// cache built+hashed dashboard js/css files forever
+	is_dash_static_asset := strings.HasPrefix(r.URL.Path, "/assets/") &&
+		(strings.HasSuffix(r.URL.Path, ".js") || strings.HasSuffix(r.URL.Path, ".css") || strings.HasSuffix(r.URL.Path, ".map"))
+
+	if is_dash_static_asset && resp.StatusCode == 200 {
+		resp.Header.Add("Cache-Control", "max-age: 604800")
+	}
+
+	return logTimeElapsed(resp)
+}
+
+func main() {
+	prometheus.MustRegister(metric)
+
+	http.Handle("/metrics", promhttp.Handler())
+	go http.ListenAndServe(":9091", nil)
+
+	http.ListenAndServe(":8080", ProxyHandler{})
+}