Maint: healthcheck package interface rework

- return concrete struct type
- Add compilation checks for implementations

internal/healthcheck/server.go

@@ -2,21 +2,20 @@ package healthcheck
 
 import (
 	"context"
-	"errors"
 	"net"
-	"net/http"
-	"time"
 
 	"github.com/qdm12/gluetun/internal/configuration"
 	"github.com/qdm12/gluetun/internal/openvpn"
 	"github.com/qdm12/golibs/logging"
 )
 
-type Server interface {
+var _ ServerRunner = (*Server)(nil)
+
+type ServerRunner interface {
 	Run(ctx context.Context, done chan<- struct{})
 }
 
-type server struct {
+type Server struct {
 	logger   logging.Logger
 	handler  *handler
 	resolver *net.Resolver
@@ -24,15 +23,9 @@ type server struct {
 	openvpn  openvpnHealth
 }
 
-type openvpnHealth struct {
-	looper       openvpn.Looper
-	healthyWait  time.Duration
-	healthyTimer *time.Timer
-}
-
 func NewServer(config configuration.Health,
-	logger logging.Logger, openvpnLooper openvpn.Looper) Server {
-	return &server{
+	logger logging.Logger, openvpnLooper openvpn.Looper) *Server {
+	return &Server{
 		logger:   logger,
 		handler:  newHandler(logger),
 		resolver: net.DefaultResolver,
@@ -43,35 +36,3 @@ func NewServer(config configuration.Health,
 		},
 	}
 }
-
-func (s *server) Run(ctx context.Context, done chan<- struct{}) {
-	defer close(done)
-
-	loopDone := make(chan struct{})
-	go s.runHealthcheckLoop(ctx, loopDone)
-
-	server := http.Server{
-		Addr:    s.config.ServerAddress,
-		Handler: s.handler,
-	}
-	serverDone := make(chan struct{})
-	go func() {
-		defer close(serverDone)
-		<-ctx.Done()
-		const shutdownGraceDuration = 2 * time.Second
-		shutdownCtx, cancel := context.WithTimeout(context.Background(), shutdownGraceDuration)
-		defer cancel()
-		if err := server.Shutdown(shutdownCtx); err != nil {
-			s.logger.Error("failed shutting down: " + err.Error())
-		}
-	}()
-
-	s.logger.Info("listening on " + s.config.ServerAddress)
-	err := server.ListenAndServe()
-	if err != nil && !errors.Is(ctx.Err(), context.Canceled) {
-		s.logger.Error(err.Error())
-	}
-
-	<-loopDone
-	<-serverDone
-}