Implement graceful shutdown of client

Install handlers for SIGTERM and command line interrupt.

cmd/signerclient/main.go

@@ -24,7 +24,9 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"os/signal"
 	"strings"
+	"syscall"
 
 	"github.com/sirupsen/logrus"
 	"gopkg.in/yaml.v3"
@@ -150,7 +152,21 @@ func startClient(configFile string, logger *logrus.Logger) error {
 
 	logger.Info("setup complete, starting client operation")
 
-	if err = signerClient.Run(context.Background()); err != nil {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
+
+	go func() {
+		<-c
+
+		logger.Info("received shutdown signal")
+
+		cancel()
+	}()
+
+	if err = signerClient.Run(ctx); err != nil {
 		return fmt.Errorf("error in client: %w", err)
 	}
 

go.mod

@@ -3,7 +3,7 @@ module git.cacert.org/cacert-gosignerclient
 go 1.19
 
 require (
-	git.cacert.org/cacert-gosigner v0.0.0-20221203104439-bc81ab84cb4a
+	git.cacert.org/cacert-gosigner v0.0.0-20221203123337-46407b368528
 	github.com/balacode/go-delta v0.1.0
 	github.com/shamaton/msgpackgen v0.3.0
 	github.com/sirupsen/logrus v1.9.0

go.sum

@@ -6,6 +6,8 @@ git.cacert.org/cacert-gosigner v0.0.0-20221202173159-afe7d23c9b6f h1:VcIwyogvdmY
 git.cacert.org/cacert-gosigner v0.0.0-20221202173159-afe7d23c9b6f/go.mod h1:OGIB5wLUhJiBhTzSXReOhGxuy7sT5VvyOyT8Ux8EGyw=
 git.cacert.org/cacert-gosigner v0.0.0-20221203104439-bc81ab84cb4a h1:yX3lhEoBQkUKu23xggAzAeYWuziCkRYktSjsAOfNGHY=
 git.cacert.org/cacert-gosigner v0.0.0-20221203104439-bc81ab84cb4a/go.mod h1:OGIB5wLUhJiBhTzSXReOhGxuy7sT5VvyOyT8Ux8EGyw=
+git.cacert.org/cacert-gosigner v0.0.0-20221203123337-46407b368528 h1:W1K/YiNp8ganr2GuOpoNC+ZcaVsG15tczpNuvAjHn+U=
+git.cacert.org/cacert-gosigner v0.0.0-20221203123337-46407b368528/go.mod h1:OGIB5wLUhJiBhTzSXReOhGxuy7sT5VvyOyT8Ux8EGyw=
 github.com/balacode/go-delta v0.1.0 h1:pwz4CMn06P2bIaIfAx3GSabMPwJp/Ww4if+7SgPYa3I=
 github.com/balacode/go-delta v0.1.0/go.mod h1:wLNrwTI3lHbPBvnLzqbHmA7HVVlm1u22XLvhbeA6t3o=
 github.com/balacode/zr v1.0.0/go.mod h1:pLeSAL3DhZ9L0JuiRkUtIX3mLOCtzBLnDhfmykbSmkE=

internal/client/client.go

@@ -91,44 +91,81 @@ type Client struct {
 }
 
 func (c *Client) Run(ctx context.Context) error {
-	protocolErrors := make(chan error)
-	framerErrors := make(chan error)
+	const componentCount = 4
+
+	protocolErrors, framerErrors := make(chan error), make(chan error)
+
+	subCtx, cancel := context.WithCancel(ctx)
+	wg := sync.WaitGroup{}
+	wg.Add(componentCount)
+
+	defer func() {
+		cancel()
+		c.logger.Info("context canceled, waiting for shutdown of components")
+		wg.Wait()
+		c.logger.Info("shutdown complete")
+	}()
 
 	go func(f protocol.Framer) {
-		framerErrors <- f.ReadFrames(ctx, c.port, c.in)
+		defer wg.Done()
+
+		err := f.ReadFrames(subCtx, c.port, c.in)
+
+		c.logger.Info("frame reading stopped")
+
+		select {
+		case framerErrors <- err:
+		case <-subCtx.Done():
+		}
 	}(c.framer)
 
 	go func(f protocol.Framer) {
-		framerErrors <- f.WriteFrames(ctx, c.port, c.out)
+		defer wg.Done()
+
+		err := f.WriteFrames(subCtx, c.port, c.out)
+
+		c.logger.Info("frame writing stopped")
+
+		select {
+		case framerErrors <- err:
+		case <-subCtx.Done():
+		}
 	}(c.framer)
 
 	go func() {
+		defer wg.Done()
+
 		clientProtocol := protocol.NewClient(c.handler, c.commands, c.in, c.out, c.logger)
 
-		protocolErrors <- clientProtocol.Handle(ctx)
+		err := clientProtocol.Handle(subCtx)
+
+		c.logger.Info("client protocol stopped")
+
+		select {
+		case protocolErrors <- err:
+		case <-subCtx.Done():
+		}
 	}()
 
-	ctx, cancelCommandLoop := context.WithCancel(ctx)
+	go func() {
+		defer wg.Done()
+
+		c.commandLoop(subCtx)
 
-	go c.commandLoop(ctx)
+		c.logger.Info("client command loop stopped")
+	}()
 
 	for {
 		select {
 		case <-ctx.Done():
-			cancelCommandLoop()
-
 			return nil
 		case err := <-framerErrors:
-			cancelCommandLoop()
-
 			if err != nil {
 				return fmt.Errorf("error from framer: %w", err)
 			}
 
 			return nil
 		case err := <-protocolErrors:
-			cancelCommandLoop()
-
 			if err != nil {
 				return fmt.Errorf("error from protocol: %w", err)
 			}