internal: add internal healthchecking to prevent websocket errors

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

internal/gounicorn/gounicorn.go

@@ -1,10 +1,13 @@
 package gounicorn
 
 import (
+	"net/http"
 	"os"
 	"os/exec"
+	"time"
 
 	log "github.com/sirupsen/logrus"
+	"goauthentik.io/internal/outpost/ak"
 )
 
 type GoUnicorn struct {
@@ -12,6 +15,7 @@ type GoUnicorn struct {
 	p       *exec.Cmd
 	started bool
 	killed  bool
+	alive   bool
 }
 
 func NewGoUnicorn() *GoUnicorn {
@@ -20,6 +24,7 @@ func NewGoUnicorn() *GoUnicorn {
 		log:     logger,
 		started: false,
 		killed:  false,
+		alive:   false,
 	}
 	g.initCmd()
 	return g
@@ -35,6 +40,10 @@ func (g *GoUnicorn) initCmd() {
 	g.p.Stderr = os.Stderr
 }
 
+func (g *GoUnicorn) IsRunning() bool {
+	return g.alive
+}
+
 func (g *GoUnicorn) Start() error {
 	if g.killed {
 		g.log.Debug("Not restarting gunicorn since we're killed")
@@ -44,9 +53,38 @@ func (g *GoUnicorn) Start() error {
 		g.initCmd()
 	}
 	g.started = true
+	go g.healthcheck()
 	return g.p.Run()
 }
 
+func (g *GoUnicorn) healthcheck() {
+	g.log.Debug("starting healthcheck")
+	h := &http.Client{
+		Transport: ak.NewUserAgentTransport("goauthentik.io go proxy healthcheck", http.DefaultTransport),
+	}
+	check := func() bool {
+		res, err := h.Get("http://localhost:8000/-/health/live/")
+		if err == nil && res.StatusCode == 204 {
+			g.alive = true
+			return true
+		}
+		return false
+	}
+
+	// Default healthcheck is every 1 second on startup
+	// once we've been healthy once, increase to 30 seconds
+	for range time.Tick(time.Second) {
+		if check() {
+			g.log.Info("backend is alive, backing off with healthchecks")
+			break
+		}
+		g.log.Debug("backend not alive yet")
+	}
+	for range time.Tick(30 * time.Second) {
+		check()
+	}
+}
+
 func (g *GoUnicorn) Kill() {
 	g.killed = true
 	err := g.p.Process.Kill()