Add graceful shutdown to ocsp server for docker.

cli/ocspserve/ocspserve.go

@@ -2,10 +2,14 @@
 package ocspserve
 
 import (
+	"context"
 	"errors"
 	"net"
 	"net/http"
+	"os"
+	"os/signal"
 	"strconv"
+	"time"
 
 	"github.com/cloudflare/cfssl/cli"
 	"github.com/cloudflare/cfssl/log"
@@ -56,7 +60,42 @@ func ocspServerMain(args []string, c cli.Config) error {
 
 	addr := net.JoinHostPort(c.Address, strconv.Itoa(c.Port))
 	log.Info("Now listening on ", addr)
-	return http.ListenAndServe(addr, nil)
+
+	server := &http.Server{Addr: addr, Handler: nil}
+
+	//gracefull shutdown on SIGTERM or SIGINT
+	//see issue https://github.com/golang/go/issues/19541
+	//see https://play.golang.org/p/LdXUYyzDxY
+	exit := make(chan struct{})
+	quit := make(chan os.Signal, 1) //use buffered version due to vet false positive . Could be unbuffered in [email protected]
+	signal.Notify(quit, os.Interrupt)
+
+	go func() {
+		defer func() {
+			if err := recover(); err != nil {
+				log.Infof("recovered: %+v\n", err)
+			}
+		}()
+		<-quit
+		d := time.Now().Add(60 * time.Second) // deadline 5s max
+		ctx, cancel := context.WithDeadline(context.Background(), d)
+
+		defer cancel()
+
+		log.Info("Shutting down server...")
+		if err := server.Shutdown(ctx); err != nil {
+			log.Fatalf("could not shutdown: %v", err)
+		}
+		close(exit)
+	}()
+	err := server.ListenAndServe()
+	<-exit
+
+	if err != http.ErrServerClosed {
+		log.Fatalf("listen: %s\n", err)
+	}
+
+	return err
 }
 
 // Command assembles the definition of Command 'ocspserve'