gce: Add support for bastions

pkg/model/gcemodel/autoscalinggroup.go

@@ -96,7 +96,7 @@ func (b *AutoscalingGroupModelBuilder) buildInstanceTemplate(c *fi.CloudupModelB
 				Preemptible:          fi.PtrTo(fi.ValueOf(ig.Spec.GCPProvisioningModel) == "SPOT"),
 				GCPProvisioningModel: ig.Spec.GCPProvisioningModel,
 
-				HasExternalIP: fi.PtrTo(subnet.Type == kops.SubnetTypePublic || subnet.Type == kops.SubnetTypeUtility),
+				HasExternalIP: fi.PtrTo(subnet.Type == kops.SubnetTypePublic || subnet.Type == kops.SubnetTypeUtility || ig.IsBastion()),
 
 				Scopes: []string{
 					"compute-rw",
@@ -104,13 +104,15 @@ func (b *AutoscalingGroupModelBuilder) buildInstanceTemplate(c *fi.CloudupModelB
 					"logging-write",
 				},
 				Metadata: map[string]fi.Resource{
-					"startup-script": startupScript,
-					//"config": resources/config.yaml $nodeset.Name
 					gcemetadata.MetadataKeyClusterName:           fi.NewStringResource(b.ClusterName()),
 					nodeidentitygce.MetadataKeyInstanceGroupName: fi.NewStringResource(ig.Name),
 				},
 			}
 
+			if startupScript != nil {
+				t.Metadata["startup-script"] = startupScript
+			}
+
 			if ig.Spec.Role == kops.InstanceGroupRoleNode {
 				autoscalerEnvVars := "os_distribution=ubuntu;arch=amd64;os=linux"
 				if strings.HasPrefix(ig.Spec.Image, "cos-cloud/") {
@@ -168,6 +170,9 @@ func (b *AutoscalingGroupModelBuilder) buildInstanceTemplate(c *fi.CloudupModelB
 
 			case kops.InstanceGroupRoleNode:
 				t.Tags = append(t.Tags, b.GCETagForRole(kops.InstanceGroupRoleNode))
+
+			case kops.InstanceGroupRoleBastion:
+				t.Tags = append(t.Tags, b.GCETagForRole(kops.InstanceGroupRoleBastion))
 			}
 			roleLabel := gce.GceLabelNameRolePrefix + ig.Spec.Role.ToLowerString()
 			t.Labels = map[string]string{

pkg/model/gcemodel/external_access.go

@@ -51,6 +51,31 @@ func (b *ExternalAccessModelBuilder) Build(c *fi.CloudupModelBuilderContext) err
 		// This is admittedly a little odd... adding a bastion shuts down direct access to the masters/nodes
 		// But I think we can always add more permissions in this case later, but we can't easily take them away
 		klog.V(2).Infof("bastion is in use; won't configure SSH access to control-plane / worker node instances")
+		network, err := b.LinkToNetwork()
+		if err != nil {
+			return err
+		}
+		b.AddFirewallRulesTasks(c, "ssh-external-to-bastion", &gcetasks.FirewallRule{
+			Lifecycle:    b.Lifecycle,
+			TargetTags:   []string{b.GCETagForRole(kops.InstanceGroupRoleBastion)},
+			Allowed:      []string{"tcp:22"},
+			SourceRanges: b.Cluster.Spec.SSHAccess,
+			Network:      network,
+		})
+		b.AddFirewallRulesTasks(c, "bastion-to-master", &gcetasks.FirewallRule{
+			Lifecycle:  b.Lifecycle,
+			TargetTags: []string{b.GCETagForRole(kops.InstanceGroupRoleControlPlane), b.GCETagForRole("Master")},
+			Allowed:    []string{"tcp:22"},
+			SourceTags: []string{b.GCETagForRole(kops.InstanceGroupRoleBastion)},
+			Network:    network,
+		})
+		b.AddFirewallRulesTasks(c, "bastion-to-node", &gcetasks.FirewallRule{
+			Lifecycle:  b.Lifecycle,
+			TargetTags: []string{b.GCETagForRole(kops.InstanceGroupRoleNode)},
+			Allowed:    []string{"tcp:22"},
+			SourceTags: []string{b.GCETagForRole(kops.InstanceGroupRoleBastion)},
+			Network:    network,
+		})
 	} else {
 		network, err := b.LinkToNetwork()
 		if err != nil {

pkg/model/gcemodel/firewall.go

@@ -180,6 +180,7 @@ func (b *GCEModelContext) AddFirewallRulesTasks(c *fi.CloudupModelBuilderContext
 	ipv4 := *rule
 	ipv4.Name = s(b.NameForFirewallRule(name))
 	ipv4.Family = gcetasks.AddressFamilyIPv4
+	if len(ipv4.SourceTags) == 0 {
 		ipv4.SourceRanges = ipv4SourceRanges
 		if len(ipv4.SourceRanges) == 0 {
 			// This is helpful because empty SourceRanges and SourceTags are interpreted as allow everything,
@@ -187,17 +188,20 @@ func (b *GCEModelContext) AddFirewallRulesTasks(c *fi.CloudupModelBuilderContext
 			ipv4.Disabled = true
 			ipv4.SourceRanges = []string{"0.0.0.0/0"}
 		}
+	}
 	c.AddTask(&ipv4)
 
 	ipv6 := *rule
 	ipv6.Name = s(b.NameForFirewallRule(name + "-ipv6"))
 	ipv6.Family = gcetasks.AddressFamilyIPv6
+	if len(ipv6.SourceTags) == 0 {
 		ipv6.SourceRanges = ipv6SourceRanges
 		if len(ipv6.SourceRanges) == 0 {
 			// We specify explicitly so the rule is in IPv6 mode
 			ipv6.Disabled = true
 			ipv6.SourceRanges = []string{"::/0"}
 		}
+	}
 	var ipv6Allowed []string
 	for _, allowed := range ipv6.Allowed {
 		// Map icmp to icmpv6; easier than maintaining separate lists