fix: [CI-21435]: Add Windows network recovery for hotpool VMs

handler/health.go

@@ -37,6 +37,7 @@ func HandleHealth() http.HandlerFunc {
 			checkDuration := getConnectivityCheckDuration(r.URL.Query())
 			err := checkInternetConnectivity(checkDuration)
 			if err != nil {
+				attemptNetworkRecovery()
 				WriteError(w, err)
 				return
 			}

handler/network_recovery_other.go

@@ -0,0 +1,10 @@
+// Copyright 2022 Drone.IO Inc. All rights reserved.
+// Use of this source code is governed by the Polyform License
+// that can be found in the LICENSE file.
+
+//go:build !windows
+
+package handler
+
+// attemptNetworkRecovery is a no-op on non-Windows platforms.
+func attemptNetworkRecovery() {}

handler/network_recovery_windows.go

@@ -0,0 +1,53 @@
+// Copyright 2022 Drone.IO Inc. All rights reserved.
+// Use of this source code is governed by the Polyform License
+// that can be found in the LICENSE file.
+
+//go:build windows
+
+package handler
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+	"time"
+
+	"github.com/sirupsen/logrus"
+)
+
+// attemptNetworkRecovery tries to restore Windows network connectivity
+// after GCE suspend/resume by renewing DHCP, flushing DNS, syncing clock,
+// and re-adding DNS servers.
+func attemptNetworkRecovery() {
+	logrus.Infoln("Attempting Windows network recovery after connectivity failure")
+	start := time.Now()
+
+	cmds := []struct {
+		name string
+		args []string
+	}{
+		{"ipconfig", []string{"/renew"}},
+		{"ipconfig", []string{"/flushdns"}},
+		{"w32tm", []string{"/resync", "/nowait"}},
+		{"netsh", []string{"interface", "ipv4", "add", "dnsserver", "Ethernet", "8.8.8.8", "index=1"}},
+		{"netsh", []string{"interface", "ipv4", "add", "dnsserver", "Ethernet", "1.1.1.1", "index=2"}},
+	}
+
+	var errors []string
+	for _, c := range cmds {
+		out, err := exec.Command(c.name, c.args...).CombinedOutput()
+		if err != nil {
+			msg := fmt.Sprintf("%s %s failed: %v (output: %s)", c.name, strings.Join(c.args, " "), err, strings.TrimSpace(string(out)))
+			errors = append(errors, msg)
+			logrus.Warnln(msg)
+		}
+	}
+
+	if len(errors) > 0 {
+		logrus.WithField("errors", len(errors)).WithField("elapsed", time.Since(start)).
+			Warnln("Network recovery completed with some errors")
+	} else {
+		logrus.WithField("elapsed", time.Since(start)).
+			Infoln("Network recovery completed successfully")
+	}
+}