Need to reset counters after recovery

caddytest/integration/reverseproxy_test.go

@@ -350,6 +350,8 @@ func TestReverseProxyHealthCheck(t *testing.T) {
 			health_port 2021
 			health_interval 10ms
 			health_timeout 100ms
+			health_passes 1
+			health_fails 1
 		}
 	}
 	`, "caddyfile")

modules/caddyhttp/reverseproxy/healthchecks.go

@@ -389,7 +389,7 @@ func (h *Handler) doActiveHealthCheck(dialInfo DialInfo, hostAddr string, upstre
 	}
 
 	markUnhealthy := func() {
-		// count failures
+		// increment failures and then check if it has reached the threshold to mark unhealthy
 		err := upstream.Host.countHealthFail(1)
 		if err != nil {
 			h.HealthChecks.Active.logger.Error("could not count active health failure",
@@ -401,12 +401,13 @@ func (h *Handler) doActiveHealthCheck(dialInfo DialInfo, hostAddr string, upstre
 			// dispatch an event that the host newly became unhealthy
 			if upstream.setHealthy(false) {
 				h.events.Emit(h.ctx, "unhealthy", map[string]any{"host": hostAddr})
+				upstream.Host.resetHealth()
 			}
 		}
 	}
 
 	markHealthy := func() {
-		// count passes
+		// increment passes and then check if it has reached the threshold to be healthy
 		err := upstream.Host.countHealthPass(1)
 		if err != nil {
 			h.HealthChecks.Active.logger.Error("could not count active health pass",
@@ -417,6 +418,7 @@ func (h *Handler) doActiveHealthCheck(dialInfo DialInfo, hostAddr string, upstre
 		if upstream.Host.HealthPasses() >= h.HealthChecks.Active.Passes {
 			if upstream.setHealthy(true) {
 				h.events.Emit(h.ctx, "healthy", map[string]any{"host": hostAddr})
+				upstream.Host.resetHealth()
 			}
 		}
 	}

modules/caddyhttp/reverseproxy/hosts.go

@@ -202,6 +202,12 @@ func (h *Host) countHealthFail(delta int) error {
 	return nil
 }
 
+// resetHealth resets the health check counters.
+func (h *Host) resetHealth() {
+	atomic.StoreInt64(&h.healthPasses, 0)
+	atomic.StoreInt64(&h.healthFails, 0)
+}
+
 // healthy returns true if the upstream is not actively marked as unhealthy.
 // (This returns the status only from the "active" health checks.)
 func (u *Upstream) healthy() bool {