add role assumption option

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add optional `--role-arn` flag to specify the role ARN to assume when interacting with Route53.
+
 ## [0.9.2] - 2024-08-26
 
 ### Added

README.md

@@ -1,6 +1,26 @@
 # dns-operator-route53
 
-`dns-operator-route53` is a controller, which runs once per management Cluster. It's responsible for creating the following DNS Records per `cluster`:
+`dns-operator-route53` is a controller, which runs once per management Cluster and watches for `Cluster` resources. It creates DNS records in Route53 for each `Cluster` in the management Cluster.
+
+## credentials
+
+`dns-operator-route53` has to communicate with AWS Route53 API.
+Therefore it needs to be configured with a set of AWS IAM credentials.
+
+```yaml
+aws:
+  accessKeyID: accesskey # AWS Access Key ID for the IAM user
+  secretAccessKey: secretkey # AWS Secret Access Key for the IAM user
+  roleARN: "" # AWS Role ARN for the IAM role to assume - optional but recommended
+```
+
+The `roleARN` is optional but recommended.
+If it is set, the operator will assume the role before interacting with Route53 using a set of temporary credentials.
+In this case, the IAM user is only used to assume the role and does not need to have any permissions to interact with Route53.
+
+## dns records
+
+`dns-operator-route53` is responsible for creating the following DNS Records per `cluster`:
 
 * `A`: `api.<clustername>.test.gigantic.io` (points to the kubernetes API IP of a `cluster`)
 * `A`: `bastion1.<clustername>.test.gigantic.io` (points to the bastion Host IP of a `cluster` - only on `OpenStack` yet)
@@ -121,4 +141,4 @@ By using the `aws` cli it's sometimes helpful to get the current created Route53
            }
        ]
    }
-   ```
+   ```

controllers/cluster_controller.go

@@ -44,6 +44,7 @@ type ClusterReconciler struct {
 
 	BaseDomain        string
 	ManagementCluster string
+	RoleArn           string
 	StaticBastionIP   string
 }
 
@@ -92,6 +93,7 @@ func (r *ClusterReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ct
 		Cluster:               cluster,
 		InfrastructureCluster: infraCluster,
 		ManagementCluster:     r.ManagementCluster,
+		RoleArn:               r.RoleArn,
 		StaticBastionIP:       r.StaticBastionIP,
 	})
 	if err != nil {

helm/dns-operator-route53/templates/deployment.yaml

@@ -39,6 +39,9 @@ spec:
         - --enable-leader-election
         - --base-domain={{ .Values.baseDomain }}
         - --management-cluster={{ .Values.managementCluster }}
+        {{ if .Values.aws.roleARN -}}
+        - --role-arn={{ .Values.aws.roleARN }}
+        {{- end }}
         {{ if .Values.staticBastionIP -}}
         - --static-bastion-ip={{ .Values.staticBastionIP }}
         {{- end }}

helm/dns-operator-route53/values.yaml

@@ -1,6 +1,7 @@
 aws:
   accessKeyID: accesskey
   secretAccessKey: secretkey
+  roleARN: ""
 
 project:
   branch: "[[ .Branch ]]"

main.go

@@ -52,6 +52,7 @@ func main() {
 		enableLeaderElection bool
 		managementCluster    string
 		metricsAddr          string
+		roleArn              string
 		staticBastionIP      string
 	)
 
@@ -62,6 +63,7 @@ func main() {
 
 	flag.StringVar(&baseDomain, "base-domain", "", "Domain for which to create the DNS entries, e.g. customer.gigantic.io.")
 	flag.StringVar(&managementCluster, "management-cluster", "", "Name of the management cluster.")
+	flag.StringVar(&roleArn, "role-arn", "", "ARN of the role to assume for the AWS API calls.")
 	flag.StringVar(&staticBastionIP, "static-bastion-ip", "", "IP address of static bastion machine for all clusters.")
 
 	flag.Parse()
@@ -93,6 +95,7 @@ func main() {
 		Client:            mgr.GetClient(),
 		BaseDomain:        baseDomain,
 		ManagementCluster: managementCluster,
+		RoleArn:           roleArn,
 		StaticBastionIP:   staticBastionIP,
 	}).SetupWithManager(mgr); err != nil {
 		setupLog.Error(err, "unable to create controller", "controller", "Cluster")

pkg/cloud/scope/clients.go

@@ -1,9 +1,7 @@
 package scope
 
 import (
-	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/awserr"
-	"github.com/aws/aws-sdk-go/aws/credentials"
 	"github.com/aws/aws-sdk-go/aws/request"
 	"github.com/aws/aws-sdk-go/service/route53"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -21,7 +19,7 @@ type AWSClients struct {
 
 // NewRoute53Client creates a new Route53 API client for a given session
 func NewRoute53Client(session cloud.Session, target runtime.Object) *route53.Route53 {
-	Route53Client := route53.New(session.Session(), &aws.Config{Credentials: credentials.NewSharedCredentials("", "")})
+	Route53Client := route53.New(session.Session(), nil)
 	Route53Client.Handlers.Build.PushFrontNamed(getUserAgentHandler())
 	Route53Client.Handlers.CompleteAttempt.PushFront(awsmetrics.CaptureRequestMetrics("dns-operator-route53"))
 	Route53Client.Handlers.Complete.PushBack(recordAWSPermissionsIssue(target))

pkg/cloud/scope/cluster.go

@@ -4,8 +4,11 @@ import (
 	"context"
 	"fmt"
 
+	"github.com/aws/aws-sdk-go/aws"
 	awsclient "github.com/aws/aws-sdk-go/aws/client"
+	"github.com/aws/aws-sdk-go/aws/credentials"
 	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/sts"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/client-go/rest"
 	capi "sigs.k8s.io/cluster-api/api/v1beta1"
@@ -31,6 +34,7 @@ type ClusterScopeParams struct {
 	Cluster               *capi.Cluster
 	InfrastructureCluster *unstructured.Unstructured
 	ManagementCluster     string
+	RoleArn               string
 	StaticBastionIP       string
 }
 
@@ -50,9 +54,36 @@ func NewClusterScope(ctx context.Context, params ClusterScopeParams) (*ClusterSc
 		return nil, microerror.Mask(err)
 	}
 
-	return &ClusterScope{
-		session: awsSession,
+	if params.RoleArn != "" {
+		// Assume Role
+		stsSvc := sts.New(awsSession)
+
+		assumeRoleOutput, err := stsSvc.AssumeRole(&sts.AssumeRoleInput{
+			RoleArn:         aws.String(params.RoleArn),
+			RoleSessionName: aws.String(fmt.Sprintf("dns-operator-route53-%s-%s", params.ManagementCluster, params.Cluster.GetName())),
+		})
+		if err != nil {
+			return nil, microerror.Mask(err)
+		}
 
+		// Use the temporary credentials from the AssumeRole response
+		creds := credentials.NewStaticCredentials(
+			*assumeRoleOutput.Credentials.AccessKeyId,
+			*assumeRoleOutput.Credentials.SecretAccessKey,
+			*assumeRoleOutput.Credentials.SessionToken,
+		)
+
+		// Create a new session with the assumed role credentials
+		awsSession, err = session.NewSession(&aws.Config{
+			Credentials: creds,
+		})
+		if err != nil {
+			return nil, microerror.Mask(err)
+		}
+	}
+
+	return &ClusterScope{
+		session:           awsSession,
 		baseDomain:        params.BaseDomain,
 		cluster:           params.Cluster,
 		infraCluster:      params.InfrastructureCluster,