core: metrics v2 (#1370)

* outposts: add ldap metrics, move ping to 9100

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

* outpost: add flow_executor metrics

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

* use port 9300 for metrics, add core metrics port

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

* outposts/controllers/k8s: add service monitor creation support

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

internal/web/proxy.go

@@ -0,0 +1,69 @@
+package web
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"goauthentik.io/internal/utils/web"
+)
+
+func (ws *WebServer) configureProxy() {
+	// Reverse proxy to the application server
+	u, _ := url.Parse("http://localhost:8000")
+	director := func(req *http.Request) {
+		req.URL.Scheme = u.Scheme
+		req.URL.Host = u.Host
+		if _, ok := req.Header["User-Agent"]; !ok {
+			// explicitly disable User-Agent so it's not set to default value
+			req.Header.Set("User-Agent", "")
+		}
+		if req.TLS != nil {
+			req.Header.Set("X-Forwarded-Proto", "https")
+		}
+	}
+	rp := &httputil.ReverseProxy{Director: director}
+	rp.ErrorHandler = ws.proxyErrorHandler
+	rp.ModifyResponse = ws.proxyModifyResponse
+	ws.m.PathPrefix("/akprox").HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		if ws.ProxyServer != nil {
+			before := time.Now()
+			ws.ProxyServer.Handle(rw, r)
+			Requests.With(prometheus.Labels{
+				"dest": "embedded_outpost",
+			}).Observe(float64(time.Since(before)))
+			return
+		}
+		ws.proxyErrorHandler(rw, r, fmt.Errorf("proxy not running"))
+	})
+	ws.m.PathPrefix("/").HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		host := web.GetHost(r)
+		before := time.Now()
+		if ws.ProxyServer != nil {
+			if ws.ProxyServer.HandleHost(host, rw, r) {
+				Requests.With(prometheus.Labels{
+					"dest": "embedded_outpost",
+				}).Observe(float64(time.Since(before)))
+				return
+			}
+		}
+		Requests.With(prometheus.Labels{
+			"dest": "py",
+		}).Observe(float64(time.Since(before)))
+		ws.log.WithField("host", host).Trace("routing to application server")
+		rp.ServeHTTP(rw, r)
+	})
+}
+
+func (ws *WebServer) proxyErrorHandler(rw http.ResponseWriter, req *http.Request, err error) {
+	ws.log.WithError(err).Warning("proxy error")
+	rw.WriteHeader(http.StatusBadGateway)
+}
+
+func (ws *WebServer) proxyModifyResponse(r *http.Response) error {
+	r.Header.Set("server", "authentik")
+	return nil
+}