Add shutdown endpoint to internal Keyper API

rolling-shutter/keyper/kprapi/http.go

@@ -31,6 +31,13 @@ func (srv *server) Ping(w http.ResponseWriter, _ *http.Request) {
 	_, _ = w.Write([]byte("pong"))
 }
 
+func (srv *server) Shutdown(_ http.ResponseWriter, _ *http.Request) {
+	srv.shutdownSig <- struct{}{}
+	// We still want to return here and thus return 200 to the caller after this.
+	// Not immediately closing open connctions is taken care
+	// of by the graceful shutdown of the http server.
+}
+
 func (srv *server) GetDecryptionKey(w http.ResponseWriter, r *http.Request, eon int, epochID kproapi.EpochID) {
 	ctx := r.Context()
 	db := database.New(srv.dbpool)

rolling-shutter/keyper/kprapi/kprapi.go

@@ -17,6 +17,7 @@ import (
 	"github.com/rs/zerolog/log"
 
 	"github.com/shutter-network/rolling-shutter/rolling-shutter/keyper/kproapi"
+	"github.com/shutter-network/rolling-shutter/rolling-shutter/medley"
 	"github.com/shutter-network/rolling-shutter/rolling-shutter/medley/retry"
 	"github.com/shutter-network/rolling-shutter/rolling-shutter/medley/service"
 	"github.com/shutter-network/rolling-shutter/rolling-shutter/p2pmsg"
@@ -33,16 +34,18 @@ type Config interface {
 }
 
 type server struct {
-	dbpool *pgxpool.Pool
-	config Config
-	p2p    P2PMessageSender
+	dbpool      *pgxpool.Pool
+	config      Config
+	p2p         P2PMessageSender
+	shutdownSig chan struct{}
 }
 
 func NewHTTPService(dbpool *pgxpool.Pool, config Config, p2p P2PMessageSender) service.Service {
 	return &server{
-		dbpool: dbpool,
-		config: config,
-		p2p:    p2p,
+		dbpool:      dbpool,
+		config:      config,
+		p2p:         p2p,
+		shutdownSig: make(chan struct{}),
 	}
 }
 
@@ -90,7 +93,12 @@ func (srv *server) Start(ctx context.Context, runner service.Runner) error {
 		Handler:           srv.setupRouter(),
 		ReadHeaderTimeout: 5 * time.Second,
 	}
+	runner.Defer(func() { close(srv.shutdownSig) })
+
 	runner.Go(httpServer.ListenAndServe)
+	runner.Go(func() error {
+		return srv.waitShutdown(ctx)
+	})
 	runner.Go(func() error {
 		<-ctx.Done()
 		shutdownCtx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
@@ -100,6 +108,24 @@ func (srv *server) Start(ctx context.Context, runner service.Runner) error {
 	return nil
 }
 
+func (srv *server) waitShutdown(ctx context.Context) error {
+	for {
+		select {
+		case _, ok := <-srv.shutdownSig:
+			if !ok {
+				// channel close without a send
+				// means we want to stop the shutdown waiter
+				// but not stop execution
+				return nil
+			}
+			return medley.ErrShutdownRequested
+		case <-ctx.Done():
+			// we canceled somewhere else
+			return nil
+		}
+	}
+}
+
 func (srv *server) setupAPIRouter(swagger *openapi3.T) http.Handler {
 	router := chi.NewRouter()
 

rolling-shutter/keyper/kproapi/oapi.yaml

@@ -16,6 +16,13 @@ paths:
       operationId: ping
       parameters:
 
+  /shutdown:
+    post:
+      description: |
+        Shut down the server
+      operationId: shutdown
+      parameters:
+
   /eons:
     get:
       description: |

rolling-shutter/medley/medley.go

@@ -26,6 +26,8 @@ const receiptPollInterval = 500 * time.Millisecond
 
 var errAddressNotFound = errors.New("address not found")
 
+var ErrShutdownRequested = errors.New("shutdown requested from user")
+
 // FindAddressIndex returns the index of the given address inside the slice of addresses or returns
 // an error, if the slice does not contain the given address.
 func FindAddressIndex(addresses []common.Address, addr common.Address) (int, error) {

rolling-shutter/medley/service/service.go

@@ -3,13 +3,16 @@ package service
 
 import (
 	"context"
+	"errors"
 	"os"
 	"os/signal"
 	"sync"
 	"syscall"
 
 	"github.com/rs/zerolog/log"
 	"golang.org/x/sync/errgroup"
+
+	"github.com/shutter-network/rolling-shutter/rolling-shutter/medley"
 )
 
 type Runner interface {
@@ -100,6 +103,11 @@ func RunWithSighandler(ctx context.Context, services ...Service) error {
 		log.Info().Msg("bye")
 		return nil
 	}
+	if errors.Is(err, medley.ErrShutdownRequested) {
+		log.Info().Msg("user shut down service")
+		log.Info().Msg("bye")
+		return nil
+	}
 
 	return err
 }