Ensure http.Transport defaults are set correctly and resolve IPv6 issue with imctl check run

Taskfile.yml

@@ -94,6 +94,8 @@ tasks:
     deps:
       - go-generate
       - protoc
+    cmds:
+      - task: format
 
   test:
     desc: run short running unit tests that do not need sudo
@@ -191,7 +193,6 @@ tasks:
       - deps
       - generate
     cmds:
-      - task: format
       - goreleaser release --snapshot --skip-publish --rm-dist
 
   release:
@@ -200,7 +201,6 @@ tasks:
       - deps
       - generate
     cmds:
-      - task: format
       - goreleaser release --rm-dist
 
   docs:

cmd/imctl/check.go

@@ -105,7 +105,7 @@ func init() {
 	runCheckCmd.Flags().Uint16Var(&args.HTTPPort, "http-port", uint16(defaultHTTPPort), "Port to connect to for 'http://' requests")
 	runCheckCmd.Flags().Uint16Var(&args.HTTPSPort, "https-port", defaultHTTPSPort, "Port to connect to for 'https://' requests")
 	runCheckCmd.Flags().Uint16Var(&args.DNSPort, "dns-port", defaultDNSPort, "Port to connect to for DNS requests")
-	runCheckCmd.Flags().StringVar(&args.DNSProto, "dns-proto", "tcp4", "Protocol to use for DNS requests one of [tcp, tcp4, tcp6, udp, udp4, udp6]")
+	runCheckCmd.Flags().StringVar(&args.DNSProto, "dns-proto", "tcp", "Protocol to use for DNS requests one of [tcp, tcp4, tcp6, udp, udp4, udp6]")
 	runCheckCmd.Flags().Uint16Var(&args.DoTPort, "dot-port", defaultDoTPort, "Port to use for DoT requests")
 	runCheckCmd.Flags().DurationVar(&args.Timeout, "check-timeout", defaultTimeout, "timeout to execute the check")
 	runCheckCmd.Flags().StringVar(&args.CACertPath, "ca-cert", "", "Path to CA cert file to trust additionally to system cert pool")
@@ -178,38 +178,26 @@ func setupClients(
 	logger logging.Logger,
 	args *runCheckArgs,
 ) (health.HTTPClientForModule, health.ResolverForModule, error) {
-	logger = logger.With(zap.String("target", args.Target))
-	if targetIP := net.ParseIP(args.Target); len(targetIP) == 0 {
-		logger.Debug("target is apparently not an IP - resolving IP address")
-		if addrs, err := net.DefaultResolver.LookupHost(ctx, args.Target); err != nil {
+	target, err := resolveTargetIP(ctx, logger, args.Target)
+	if err != nil {
 		return nil, nil, err
-		} else {
-			logger.Debug("Resolved target addresses", zap.Strings("resolvedAddresses", addrs))
-			//nolint:gosec // no need for cryptographic security when picking a random IP address to contact
-			idx := rand.Intn(len(addrs))
-			logger.Debug("Picked random address", zap.String("newTargetAddress", addrs[idx]))
-			args.Target = addrs[idx]
 	}
-	} else {
-		logger.Debug("target is an IP address - will be set for clients")
-	}
-
 	healthCfg := health.Config{
 		Client: health.ClientsConfig{
 			HTTP: health.Server{
-				IP:   args.Target,
+				IP:   target,
 				Port: args.HTTPPort,
 			},
 			HTTPS: health.Server{
-				IP:   args.Target,
+				IP:   target,
 				Port: args.HTTPSPort,
 			},
 			DNS: health.Server{
-				IP:   args.Target,
+				IP:   target,
 				Port: args.DNSPort,
 			},
 			DoT: health.Server{
-				IP:   args.Target,
+				IP:   target,
 				Port: args.DoTPort,
 			},
 		},
@@ -266,3 +254,29 @@ func addCACertToPool(pool *x509.CertPool) (err error) {
 	pool.AppendCertsFromPEM(buffer.Bytes())
 	return nil
 }
+
+func resolveTargetIP(ctx context.Context, logger logging.Logger, target string) (string, error) {
+	logger = logger.With(zap.String("target", target))
+	if targetIP := net.ParseIP(target); targetIP != nil && len(targetIP) > 0 {
+		logger.Debug("target is an IP address - will be set for clients")
+		return target, nil
+	}
+
+	logger.Debug("target is apparently not an IP - resolving IP address")
+	if addrs, err := net.DefaultResolver.LookupHost(ctx, args.Target); err != nil {
+		return "", err
+	} else {
+		logger.Debug("Resolved target addresses", zap.Strings("resolvedAddresses", addrs))
+		//nolint:gosec // no need for cryptographic security when picking a random IP address to contact
+		pickedAddr := addrs[rand.Intn(len(addrs))]
+		logger.Debug("Picked random address", zap.String("newTargetAddress", pickedAddr))
+		if parsed := net.ParseIP(pickedAddr); parsed == nil {
+			logger.Error("Could not parse resolved IP", zap.String("addr", pickedAddr))
+			return "", errors.New("could not parse resolved IP")
+		} else if parsed.To4() == nil {
+			pickedAddr = fmt.Sprintf("[%s]", pickedAddr)
+		}
+		args.Target = pickedAddr
+	}
+	return target, nil
+}

pkg/health/http_client.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net"
 	gohttp "net/http"
+	"time"
 
 	"golang.org/x/net/http2"
 )
@@ -44,6 +45,10 @@ func HTTPClient(cfg Config, tlsConfig *tls.Config) *gohttp.Client {
 	)
 
 	roundTripper := &gohttp.Transport{
+		MaxIdleConns:          100,
+		IdleConnTimeout:       90 * time.Second,
+		TLSHandshakeTimeout:   10 * time.Second,
+		ExpectContinueTimeout: 1 * time.Second,
 		DialContext: func(ctx context.Context, _, _ string) (net.Conn, error) {
 			return netDialer.DialContext(ctx, "tcp", fmt.Sprintf("%s:%d", httpEndpoint.IP, httpEndpoint.Port))
 		},