Feature: faster healthcheck, fix #283

internal/healthcheck/handler.go

@@ -1,21 +1,25 @@
 package healthcheck
 
 import (
-	"net"
+	"errors"
 	"net/http"
+	"sync"
 
 	"github.com/qdm12/golibs/logging"
 )
 
 type handler struct {
-	logger   logging.Logger
-	resolver *net.Resolver
+	logger      logging.Logger
+	healthErr   error
+	healthErrMu sync.RWMutex
 }
 
-func newHandler(logger logging.Logger, resolver *net.Resolver) http.Handler {
+var errHealthcheckNotRunYet = errors.New("healthcheck did not run yet")
+
+func newHandler(logger logging.Logger) *handler {
 	return &handler{
-		logger:   logger,
-		resolver: resolver,
+		logger:    logger,
+		healthErr: errHealthcheckNotRunYet,
 	}
 }
 
@@ -24,11 +28,22 @@ func (h *handler) ServeHTTP(responseWriter http.ResponseWriter, request *http.Re
 		http.Error(responseWriter, "method not supported for healthcheck", http.StatusBadRequest)
 		return
 	}
-	err := healthCheck(request.Context(), h.resolver)
-	if err != nil {
+	if err := h.getErr(); err != nil {
 		h.logger.Error(err)
 		http.Error(responseWriter, err.Error(), http.StatusInternalServerError)
 		return
 	}
 	responseWriter.WriteHeader(http.StatusOK)
 }
+
+func (h *handler) setErr(err error) {
+	h.healthErrMu.Lock()
+	defer h.healthErrMu.Unlock()
+	h.healthErr = err
+}
+
+func (h *handler) getErr() (err error) {
+	h.healthErrMu.RLock()
+	defer h.healthErrMu.RUnlock()
+	return h.healthErr
+}