gce: use per instancegroup serviceaccounts

We no longer set the cloudconfig serviceaccount on new clusters, and
instead use a per-IG setting if this is not set.

pkg/model/gcemodel/autoscalinggroup.go

@@ -156,14 +156,6 @@ func (b *AutoscalingGroupModelBuilder) buildInstanceTemplate(c *fi.ModelBuilderC
 			}
 			t.Subnet = b.LinkToSubnet(subnet)
 
-			if b.Cluster.Spec.CloudConfig.GCEServiceAccount != "" {
-				klog.Infof("VMs using Service Account: %v", b.Cluster.Spec.CloudConfig.GCEServiceAccount)
-				// b.Cluster.Spec.GCEServiceAccount = c.GCEServiceAccount
-			} else {
-				klog.Warning("VMs will be configured to use the GCE default compute Service Account! This is an anti-pattern")
-				klog.Warning("Use a pre-created Service Account with the flag: --gce-service-account=account@projectname.iam.gserviceaccount.com")
-				b.Cluster.Spec.CloudConfig.GCEServiceAccount = "default"
-			}
 			t.ServiceAccounts = append(t.ServiceAccounts, b.LinkToServiceAccount(ig))
 
 			//labels, err := b.CloudTagsForInstanceGroup(ig)

pkg/model/gcemodel/context.go

@@ -26,6 +26,8 @@ import (
 )
 
 type GCEModelContext struct {
+	ProjectID string
+
 	*model.KopsModelContext
 }
 
@@ -103,11 +105,37 @@ func (c *GCEModelContext) NetworkingIsGCERoutes() bool {
 
 // LinkToServiceAccount returns a link to the GCE ServiceAccount object for VMs in the given role
 func (c *GCEModelContext) LinkToServiceAccount(ig *kops.InstanceGroup) *gcetasks.ServiceAccount {
-	// This is a legacy setting because the nodes & control-plane run under the same serviceaccount
-	klog.Warningf("using legacy spec.cloudConfig.gceServiceAccount=%q setting", c.Cluster.Spec.CloudConfig.GCEServiceAccount)
-	return &gcetasks.ServiceAccount{
-		Name:   s("shared"),
-		Email:  &c.Cluster.Spec.CloudConfig.GCEServiceAccount,
-		Shared: fi.Bool(true),
+	if c.Cluster.Spec.CloudConfig.GCEServiceAccount != "" {
+		// This is a legacy setting because the nodes & control-plane run under the same serviceaccount
+		klog.Warningf("using legacy spec.cloudConfig.gceServiceAccount=%q setting", c.Cluster.Spec.CloudConfig.GCEServiceAccount)
+		return &gcetasks.ServiceAccount{
+			Name:   s("shared"),
+			Email:  &c.Cluster.Spec.CloudConfig.GCEServiceAccount,
+			Shared: fi.Bool(true),
+		}
 	}
+
+	role := ig.Spec.Role
+
+	name := ""
+	switch role {
+	case kops.InstanceGroupRoleAPIServer, kops.InstanceGroupRoleMaster:
+		name = "control-plane"
+
+	case kops.InstanceGroupRoleBastion:
+		name = "bastion"
+
+	case kops.InstanceGroupRoleNode:
+		name = "node"
+
+	default:
+		klog.Fatalf("unknown role %q", role)
+	}
+
+	accountID := c.SafeObjectName(name)
+	projectID := c.ProjectID
+
+	email := accountID + "@" + projectID + ".iam.gserviceaccount.com"
+
+	return &gcetasks.ServiceAccount{Name: s(name), Email: s(email)}
 }

pkg/model/gcemodel/service_accounts.go

@@ -17,6 +17,8 @@ limitations under the License.
 package gcemodel
 
 import (
+	"k8s.io/klog/v2"
+	"k8s.io/kops/pkg/apis/kops"
 	"k8s.io/kops/upup/pkg/fi"
 	"k8s.io/kops/upup/pkg/fi/cloudup/gcetasks"
 )
@@ -43,5 +45,84 @@ func (b *ServiceAccountsBuilder) Build(c *fi.ModelBuilderContext) error {
 		return nil
 	}
 
+	doneEmails := make(map[string]bool)
+	for _, ig := range b.InstanceGroups {
+		link := b.LinkToServiceAccount(ig)
+		if fi.BoolValue(link.Shared) {
+			c.EnsureTask(link)
+			continue
+		}
+
+		if doneEmails[*link.Email] {
+			continue
+		}
+		doneEmails[*link.Email] = true
+
+		serviceAccount := &gcetasks.ServiceAccount{
+			Name:      link.Name,
+			Email:     link.Email,
+			Lifecycle: b.Lifecycle,
+		}
+		switch ig.Spec.Role {
+		case kops.InstanceGroupRoleAPIServer, kops.InstanceGroupRoleMaster:
+			serviceAccount.Description = fi.String("kubernetes control-plane instances")
+		case kops.InstanceGroupRoleNode:
+			serviceAccount.Description = fi.String("kubernetes worker nodes")
+		case kops.InstanceGroupRoleBastion:
+			serviceAccount.Description = fi.String("bastion nodes")
+		default:
+			klog.Warningf("unknown instance role %q", ig.Spec.Role)
+		}
+		c.AddTask(serviceAccount)
+
+		role := ig.Spec.Role
+		if role == kops.InstanceGroupRoleAPIServer {
+			// Because these share a serviceaccount, we share a role
+			role = kops.InstanceGroupRoleMaster
+		}
+
+		if err := b.addInstanceGroupServiceAccountPermissions(c, *serviceAccount.Email, role); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (b *ServiceAccountsBuilder) addInstanceGroupServiceAccountPermissions(c *fi.ModelBuilderContext, serviceAccountEmail string, role kops.InstanceGroupRole) error {
+	member := "serviceAccount:" + serviceAccountEmail
+
+	// Ideally we would use a custom role here, but the deletion of a custom role takes 7 days,
+	// which means we can't easily recycle cluster names.
+	// If we can find a solution, we can easily switch to a custom role.
+
+	switch role {
+	case kops.InstanceGroupRoleMaster:
+		// We reuse the GKE role
+		c.AddTask(&gcetasks.ProjectIAMBinding{
+			Name:      s("serviceaccount-control-plane"),
+			Lifecycle: b.Lifecycle,
+
+			Project: s(b.ProjectID),
+			Member:  s(member),
+			Role:    s("roles/container.serviceAgent"),
+		})
+
+	case kops.InstanceGroupRoleNode:
+		// Known permissions:
+		//  * compute.zones.list (to find out region; we could replace this with string manipulation)
+		//  * compute.instances.list (for discovery; we don't need in the case of a load balancer or DNS)
+
+		// We use the GCE viewer role
+
+		c.AddTask(&gcetasks.ProjectIAMBinding{
+			Name:      s("serviceaccount-nodes"),
+			Lifecycle: b.Lifecycle,
+
+			Project: s(b.ProjectID),
+			Member:  s(member),
+			Role:    s("roles/compute.viewer"),
+		})
+	}
 	return nil
 }

pkg/model/gcemodel/storageacl.go

@@ -18,6 +18,7 @@ package gcemodel
 
 import (
 	"fmt"
+	"strings"
 
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/klog/v2"
@@ -40,17 +41,24 @@ type StorageAclBuilder struct {
 var _ fi.ModelBuilder = &NetworkModelBuilder{}
 
 // Build creates the tasks that set up storage acls
-func (b *StorageAclBuilder) Build(c *fi.ModelBuilderContext) error {
-	serviceAccount, err := b.Cloud.ServiceAccount()
-	if err != nil {
-		return fmt.Errorf("error fetching ServiceAccount: %v", err)
-	}
 
+func (b *StorageAclBuilder) Build(c *fi.ModelBuilderContext) error {
 	if featureflag.GoogleCloudBucketACL.Enabled() {
+		if b.Cluster.Spec.CloudConfig.GCEServiceAccount == "" {
+			return fmt.Errorf("featureflag GoogleCloudBucketACL not supported with per-instancegroup GCEServiceAccount")
+		}
+
+		klog.Warningf("featureflag GoogleCloudBucketACL is no longer recommended; use per-instancegroup GCEServiceAccounts instead")
+
+		gceDefaultServiceAccount, err := b.Cloud.ServiceAccount()
+		if err != nil {
+			return fmt.Errorf("error fetching default ServiceAccount: %w", err)
+		}
+
 		clusterPath := b.Cluster.Spec.ConfigBase
 		p, err := vfs.Context.BuildVfsPath(clusterPath)
 		if err != nil {
-			return fmt.Errorf("cannot parse cluster path %q: %v", clusterPath, err)
+			return fmt.Errorf("cannot parse cluster path %q: %w", clusterPath, err)
 		}
 
 		switch p := p.(type) {
@@ -62,7 +70,7 @@ func (b *StorageAclBuilder) Build(c *fi.ModelBuilderContext) error {
 				Name:      s("serviceaccount-statestore-list"),
 				Lifecycle: b.Lifecycle,
 				Bucket:    s(p.Bucket()),
-				Entity:    s("user-" + serviceAccount),
+				Entity:    s("user-" + gceDefaultServiceAccount),
 				Role:      s("READER"),
 			})
 		}
@@ -80,27 +88,121 @@ func (b *StorageAclBuilder) Build(c *fi.ModelBuilderContext) error {
 
 		buckets := sets.NewString()
 		for _, p := range writeablePaths {
-			if gcsPath, ok := p.(*vfs.GSPath); ok {
-				bucket := gcsPath.Bucket()
-				if buckets.Has(bucket) {
-					continue
-				}
-
-				klog.Warningf("adding bucket level write ACL to gs://%s to support etcd backup", bucket)
-
-				c.AddTask(&gcetasks.StorageBucketAcl{
-					Name:      s("serviceaccount-backup-readwrite-" + bucket),
-					Lifecycle: b.Lifecycle,
-					Bucket:    s(bucket),
-					Entity:    s("user-" + serviceAccount),
-					Role:      s("WRITER"),
-				})
-
-				buckets.Insert(bucket)
-			} else {
+			gcsPath, ok := p.(*vfs.GSPath)
+			if !ok {
 				klog.Warningf("unknown path, can't apply IAM policy: %q", p)
+				continue
 			}
+
+			bucket := gcsPath.Bucket()
+			if buckets.Has(bucket) {
+				continue
+			}
+			buckets.Insert(bucket)
+
+			klog.Warningf("adding bucket level write ACL to gs://%s to support etcd backup", bucket)
+
+			c.AddTask(&gcetasks.StorageBucketAcl{
+				Name:      s("serviceaccount-backup-readwrite-" + bucket),
+				Lifecycle: b.Lifecycle,
+				Bucket:    s(bucket),
+				Entity:    s("user-" + gceDefaultServiceAccount),
+				Role:      s("WRITER"),
+			})
+		}
+
+		return nil
+	}
+
+	type serviceAccountRole struct {
+		Email string
+		Role  kops.InstanceGroupRole
+	}
+	serviceAccountRoles := make(map[serviceAccountRole]bool)
+
+	for _, ig := range b.InstanceGroups {
+		serviceAccount := b.LinkToServiceAccount(ig)
+
+		email := *serviceAccount.Email
+		serviceAccountRoles[serviceAccountRole{Email: email, Role: ig.Spec.Role}] = true
+	}
+
+	for serviceAccountRole := range serviceAccountRoles {
+		role := serviceAccountRole.Role
+
+		nodeRole, err := iam.BuildNodeRoleSubject(role, false)
+		if err != nil {
+			return err
+		}
+
+		buckets := sets.NewString()
+
+		writeablePaths, err := iam.WriteableVFSPaths(b.Cluster, nodeRole)
+		if err != nil {
+			return err
+		}
+		for _, p := range writeablePaths {
+			gcsPath, ok := p.(*vfs.GSPath)
+			if !ok {
+				klog.Warningf("unknown path, can't apply IAM policy: %q", p)
+				continue
+			}
+
+			bucket := gcsPath.Bucket()
+			if buckets.Has(bucket) {
+				continue
+			}
+			buckets.Insert(bucket)
+
+			nameForTask := strings.ToLower(string(role))
+
+			klog.Warningf("adding bucket level write IAM for role %q to gs://%s to support etcd backup", bucket, role)
+
+			c.AddTask(&gcetasks.StorageBucketIAM{
+				Name:      s("objectadmin-" + bucket + "-serviceaccount-" + nameForTask),
+				Lifecycle: b.Lifecycle,
+				Bucket:    s(bucket),
+				Member:    s("serviceAccount:" + serviceAccountRole.Email),
+				Role:      s("roles/storage.objectAdmin"),
+			})
+		}
+
+		// Add bucket read permissions if we need to read from the bucket
+		readablePaths, err := iam.ReadableStatePaths(b.Cluster, nodeRole)
+		if err != nil {
+			return err
+		}
+		if len(readablePaths) != 0 {
+			p, err := vfs.Context.BuildVfsPath(b.Cluster.Spec.ConfigStore)
+			if err != nil {
+				return fmt.Errorf("cannot parse VFS path %q: %v", b.Cluster.Spec.ConfigStore, err)
+			}
+
+			gcsPath, ok := p.(*vfs.GSPath)
+			if !ok {
+				klog.Warningf("unknown path, can't apply IAM policy: %q", p)
+				continue
+			}
+			bucket := gcsPath.Bucket()
+			if buckets.Has(bucket) {
+				// Already marked as writeable; we can skip
+				continue
+			}
+			buckets.Insert(bucket)
+
+			nameForTask := strings.ToLower(string(role))
+
+			klog.Warningf("adding bucket level read IAM to gs://%s for role %q", bucket, role)
+
+			c.AddTask(&gcetasks.StorageBucketIAM{
+				Name:      s("objectviewer-" + bucket + "-serviceaccount-" + nameForTask),
+				Lifecycle: b.Lifecycle,
+				Bucket:    s(bucket),
+				Member:    s("serviceAccount:" + serviceAccountRole.Email),
+				Role:      s("roles/storage.objectViewer"),
+			})
 		}
 	}
+
 	return nil
 }

upup/pkg/fi/cloudup/apply_cluster.go

@@ -589,6 +589,7 @@ func (c *ApplyClusterCmd) Run(ctx context.Context) error {
 			)
 		case kops.CloudProviderGCE:
 			gceModelContext := &gcemodel.GCEModelContext{
+				ProjectID:        project,
 				KopsModelContext: modelContext,
 			}
 

upup/pkg/fi/cloudup/new_cluster.go

@@ -367,10 +367,6 @@ func setupVPC(opt *NewClusterOptions, cluster *api.Cluster) error {
 			// TODO remove this logging?
 			klog.Infof("VMs will be configured to use specified Service Account: %v", opt.GCEServiceAccount)
 			cluster.Spec.CloudConfig.GCEServiceAccount = opt.GCEServiceAccount
-		} else {
-			klog.Warning("VMs will be configured to use the GCE default compute Service Account! This is an anti-pattern")
-			klog.Warning("Use a pre-created Service Account with the flag: --gce-service-account=account@projectname.iam.gserviceaccount.com")
-			cluster.Spec.CloudConfig.GCEServiceAccount = "default"
 		}
 
 	case api.CloudProviderOpenstack: