Add config to disable hosts file modification

This change introduces a new configuration setting 'modify-hosts-file'
that allows users to disable CRC's automatic modification of the
/etc/hosts file. The setting defaults to true to maintain backward
compatibility with existing installations.

Author: tricktron

pkg/crc/config/settings.go

@@ -27,6 +27,7 @@ const (
 	ProxyCAFile              = "proxy-ca-file"
 	ConsentTelemetry         = "consent-telemetry"
 	EnableClusterMonitoring  = "enable-cluster-monitoring"
+	ModifyHostsFile          = "modify-hosts-file"
 	KubeAdminPassword        = "kubeadmin-password"
 	DeveloperPassword        = "developer-password"
 	Preset                   = "preset"
@@ -107,6 +108,9 @@ func RegisterSettings(cfg *Config) {
 	cfg.AddSetting(EnableClusterMonitoring, false, ValidateBool, SuccessfullyApplied,
 		"Enable cluster monitoring Operator (true/false, default: false)")
 
+	cfg.AddSetting(ModifyHostsFile, true, ValidateBool, SuccessfullyApplied,
+		"Allow CRC to modify the system hosts file (true/false, default: true)")
+
 	// Telemeter Configuration
 	cfg.AddSetting(ConsentTelemetry, "", validateYesNo, SuccessfullyApplied,
 		"Consent to collection of anonymous usage data (yes/no)")

pkg/crc/config/settings_test.go

@@ -251,6 +251,9 @@ var configDefaultValuesTestArguments = []struct {
 	{
 		EnableClusterMonitoring, false,
 	},
+	{
+		ModifyHostsFile, true,
+	},
 	{
 		ConsentTelemetry, "",
 	},
@@ -331,6 +334,9 @@ var configProvidedValuesTestArguments = []struct {
 	{
 		EnableClusterMonitoring, true,
 	},
+	{
+		ModifyHostsFile, false,
+	},
 	{
 		ConsentTelemetry, "yes",
 	},

pkg/crc/machine/client.go

@@ -64,6 +64,10 @@ func (client *client) networkMode() network.Mode {
 	return crcConfig.GetNetworkMode(client.config)
 }
 
+func (client *client) modifyHostsFile() bool {
+	return client.config.Get(crcConfig.ModifyHostsFile).AsBool()
+}
+
 func (client *client) monitoringEnabled() bool {
 	return client.config.Get(crcConfig.EnableClusterMonitoring).AsBool()
 }

pkg/crc/machine/start.go

@@ -483,8 +483,9 @@ func (client *client) Start(ctx context.Context, startConfig types.StartConfig)
 		SSHRunner: sshRunner,
 		IP:        instanceIP,
 		// TODO: should be more finegrained
-		BundleMetadata: *vm.bundle,
-		NetworkMode:    client.networkMode(),
+		BundleMetadata:  *vm.bundle,
+		NetworkMode:     client.networkMode(),
+		ModifyHostsFile: client.modifyHostsFile(),
 	}
 
 	// Run the DNS server inside the VM
@@ -508,7 +509,11 @@ func (client *client) Start(ctx context.Context, startConfig types.StartConfig)
 	logging.Info("Check DNS query from host...")
 	if err := dns.CheckCRCLocalDNSReachableFromHost(servicePostStartConfig); err != nil {
 		if !client.useVSock() {
-			return nil, errors.Wrap(err, "Failed to query DNS from host")
+			msg := "Failed to query DNS from host"
+			if !servicePostStartConfig.ModifyHostsFile {
+				msg += " (modify-hosts-file=false). Ensure your system DNS/hosts entries resolve the CRC domains."
+			}
+			return nil, errors.Wrap(err, msg)
 		}
 		logging.Warn(fmt.Sprintf("Failed to query DNS from host: %v", err))
 	}

pkg/crc/services/dns/dns_darwin.go

@@ -33,8 +33,12 @@ type resolverFileValues struct {
 
 func runPostStartForOS(serviceConfig services.ServicePostStartConfig) error {
 	// Update /etc/hosts file for host
-	if err := addOpenShiftHosts(serviceConfig); err != nil {
-		return err
+	if serviceConfig.ModifyHostsFile {
+		if err := addOpenShiftHosts(serviceConfig); err != nil {
+			return err
+		}
+	} else {
+		logging.Infof("Skipping hosts file modification because 'modify-hosts-file' is set to false")
 	}
 
 	if serviceConfig.NetworkMode == network.UserNetworkingMode {
@@ -86,7 +90,7 @@ func createResolverFile(instanceIP string, domain string, filename string) (bool
 	}
 
 	path := filepath.Join("/", "etc", "resolver", filename)
-	return crcos.WriteFileIfContentChanged(path, resolverFile.Bytes(), 0644)
+	return crcos.WriteFileIfContentChanged(path, resolverFile.Bytes(), 0o644)
 }
 
 // restartNetwork is required to update the resolver file on OSx.

pkg/crc/services/dns/dns_linux.go

@@ -1,11 +1,18 @@
 package dns
 
 import (
+	"github.com/crc-org/crc/v2/pkg/crc/logging"
 	"github.com/crc-org/crc/v2/pkg/crc/services"
 )
 
 func runPostStartForOS(serviceConfig services.ServicePostStartConfig) error {
 	// We might need to set the firewall here to forward
 	// Update /etc/hosts file for host
-	return addOpenShiftHosts(serviceConfig)
+	if serviceConfig.ModifyHostsFile {
+		return addOpenShiftHosts(serviceConfig)
+	}
+
+	logging.Infof("Skipping hosts file modification because 'modify-hosts-file' is set to false")
+
+	return nil
 }

pkg/crc/services/dns/dns_windows.go

@@ -3,6 +3,7 @@ package dns
 import (
 	"fmt"
 
+	"github.com/crc-org/crc/v2/pkg/crc/logging"
 	"github.com/crc-org/crc/v2/pkg/crc/network"
 	"github.com/crc-org/crc/v2/pkg/crc/services"
 )
@@ -11,5 +12,12 @@ func runPostStartForOS(serviceConfig services.ServicePostStartConfig) error {
 	if serviceConfig.NetworkMode != network.UserNetworkingMode {
 		return fmt.Errorf("only user-mode networking is supported on Windows")
 	}
-	return addOpenShiftHosts(serviceConfig)
+
+	if serviceConfig.ModifyHostsFile {
+		return addOpenShiftHosts(serviceConfig)
+	}
+
+	logging.Infof("Skipping hosts file modification because 'modify-hosts-file' is set to false")
+
+	return nil
 }

pkg/crc/services/services.go

@@ -7,9 +7,10 @@ import (
 )
 
 type ServicePostStartConfig struct {
-	Name           string
-	SSHRunner      *ssh.Runner
-	BundleMetadata bundle.CrcBundleInfo
-	IP             string
-	NetworkMode    network.Mode
+	Name            string
+	SSHRunner       *ssh.Runner
+	BundleMetadata  bundle.CrcBundleInfo
+	IP              string
+	NetworkMode     network.Mode
+	ModifyHostsFile bool
 }