metrics: fix global state reset on policy reload

lib/interface.go

@@ -41,7 +41,7 @@ func (state *State) ChallengeFailed(r *http.Request, reg *challenge.Registration
 	}
 	logger.Warn("challenge failed", "challenge", reg.Name, "err", err, "redirect", redirect)
 
-	state.metrics.Challenge(reg.Name, "fail")
+	metrics.Challenge(reg.Name, "fail")
 }
 
 func (state *State) ChallengePassed(r *http.Request, reg *challenge.Registration, redirect string, logger *slog.Logger) {
@@ -50,7 +50,7 @@ func (state *State) ChallengePassed(r *http.Request, reg *challenge.Registration
 	}
 	logger.Warn("challenge passed", "challenge", reg.Name, "redirect", redirect)
 
-	state.metrics.Challenge(reg.Name, "pass")
+	metrics.Challenge(reg.Name, "pass")
 }
 
 func (state *State) ChallengeIssued(r *http.Request, reg *challenge.Registration, redirect string, logger *slog.Logger) {
@@ -59,23 +59,23 @@ func (state *State) ChallengeIssued(r *http.Request, reg *challenge.Registration
 	}
 	logger.Info("challenge issued", "challenge", reg.Name, "redirect", redirect)
 
-	state.metrics.Challenge(reg.Name, "issue")
+	metrics.Challenge(reg.Name, "issue")
 }
 
 func (state *State) ChallengeChecked(r *http.Request, reg *challenge.Registration, redirect string, logger *slog.Logger) {
-	state.metrics.Challenge(reg.Name, "check")
+	metrics.Challenge(reg.Name, "check")
 }
 
 func (state *State) RuleHit(r *http.Request, name string, logger *slog.Logger) {
-	state.metrics.Rule(name, "hit")
+	metrics.Rule(name, "hit")
 }
 
 func (state *State) RuleMiss(r *http.Request, name string, logger *slog.Logger) {
-	state.metrics.Rule(name, "miss")
+	metrics.Rule(name, "miss")
 }
 
 func (state *State) ActionHit(r *http.Request, name policy.RuleAction, logger *slog.Logger) {
-	state.metrics.Action(name)
+	metrics.Action(name)
 }
 
 func (state *State) Logger(r *http.Request) *slog.Logger {

lib/metrics.go

@@ -40,3 +40,11 @@ func (metrics *stateMetrics) Action(action policy.RuleAction) {
 func (metrics *stateMetrics) Challenge(name, result string) {
 	metrics.challenges.With(prometheus.Labels{"challenge": name, "action": result}).Inc()
 }
+
+func (metrics *stateMetrics) Reset() {
+	metrics.rules.Reset()
+	metrics.actions.Reset()
+	metrics.challenges.Reset()
+}
+
+var metrics = newMetrics()

lib/state.go

@@ -44,8 +44,6 @@ type State struct {
 	close chan struct{}
 
 	Mux *http.ServeMux
-
-	metrics *stateMetrics
 }
 
 func NewState(p policy.Policy, opt settings.Settings, settings policy.StateSettings) (handler http.Handler, err error) {
@@ -53,7 +51,7 @@ func NewState(p policy.Policy, opt settings.Settings, settings policy.StateSetti
 	state.close = make(chan struct{})
 	state.settings = settings
 	state.opt = opt
-	state.metrics = newMetrics()
+	metrics.Reset()
 	state.client = &http.Client{
 		CheckRedirect: func(req *http.Request, via []*http.Request) error {
 			return http.ErrUseLastResponse