[node operator] Add GCP client

Signed-off-by: Malte Poll <mp@edgeless.systems>

operators/constellation-node-operator/internal/gcp/client/scalinggroup.go

@@ -0,0 +1,118 @@
+package client
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	computepb "google.golang.org/genproto/googleapis/cloud/compute/v1"
+)
+
+// GetScalingGroupImage returns the image URI of the scaling group.
+func (c *Client) GetScalingGroupImage(ctx context.Context, scalingGroupID string) (string, error) {
+	instanceTemplate, err := c.getScalingGroupTemplate(ctx, scalingGroupID)
+	if err != nil {
+		return "", err
+	}
+	return instanceTemplateSourceImage(instanceTemplate)
+}
+
+// SetScalingGroupImage sets the image URI of the scaling group.
+func (c *Client) SetScalingGroupImage(ctx context.Context, scalingGroupID, imageURI string) error {
+	project, zone, instanceGroupName, err := splitInstanceGroupID(scalingGroupID)
+	if err != nil {
+		return err
+	}
+	// get current template
+	instanceTemplate, err := c.getScalingGroupTemplate(ctx, scalingGroupID)
+	if err != nil {
+		return err
+	}
+	// check if template already uses the same image
+	oldImageURI, err := instanceTemplateSourceImage(instanceTemplate)
+	if err != nil {
+		return err
+	}
+	if oldImageURI == imageURI {
+		return nil
+	}
+
+	// clone template with desired image
+	if instanceTemplate.Name == nil {
+		return fmt.Errorf("instance template of scaling group %q has no name", scalingGroupID)
+	}
+	instanceTemplate.Properties.Disks[0].InitializeParams.SourceImage = &imageURI
+	newTemplateName, err := generateInstanceTemplateName(*instanceTemplate.Name)
+	if err != nil {
+		return err
+	}
+	instanceTemplate.Name = &newTemplateName
+	op, err := c.instanceTemplateAPI.Insert(ctx, &computepb.InsertInstanceTemplateRequest{
+		Project:                  project,
+		InstanceTemplateResource: instanceTemplate,
+	})
+	if err != nil {
+		return fmt.Errorf("cloning instance template: %w", err)
+	}
+	if err := op.Wait(ctx); err != nil {
+		return fmt.Errorf("waiting for cloned instance template: %w", err)
+	}
+
+	newTemplateURI := joinInstanceTemplateURI(project, newTemplateName)
+	// update instance group manager to use new template
+	op, err = c.instanceGroupManagersAPI.SetInstanceTemplate(ctx, &computepb.SetInstanceTemplateInstanceGroupManagerRequest{
+		InstanceGroupManager: instanceGroupName,
+		Project:              project,
+		Zone:                 zone,
+		InstanceGroupManagersSetInstanceTemplateRequestResource: &computepb.InstanceGroupManagersSetInstanceTemplateRequest{
+			InstanceTemplate: &newTemplateURI,
+		},
+	})
+	if err != nil {
+		return fmt.Errorf("setting instance template: %w", err)
+	}
+	if err := op.Wait(ctx); err != nil {
+		return fmt.Errorf("waiting for setting instance template: %w", err)
+	}
+	return nil
+}
+
+func (c *Client) getScalingGroupTemplate(ctx context.Context, scalingGroupID string) (*computepb.InstanceTemplate, error) {
+	project, zone, instanceGroupName, err := splitInstanceGroupID(scalingGroupID)
+	if err != nil {
+		return nil, err
+	}
+	instanceGroupManager, err := c.instanceGroupManagersAPI.Get(ctx, &computepb.GetInstanceGroupManagerRequest{
+		InstanceGroupManager: instanceGroupName,
+		Project:              project,
+		Zone:                 zone,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("getting instance group manager %q: %w", instanceGroupName, err)
+	}
+	if instanceGroupManager.InstanceTemplate == nil {
+		return nil, fmt.Errorf("instance group manager %q has no instance template", instanceGroupName)
+	}
+	instanceTemplateProject, instanceTemplateName, err := splitInstanceTemplateID(uriNormalize(*instanceGroupManager.InstanceTemplate))
+	if err != nil {
+		return nil, fmt.Errorf("splitting instance template name: %w", err)
+	}
+	instanceTemplate, err := c.instanceTemplateAPI.Get(ctx, &computepb.GetInstanceTemplateRequest{
+		InstanceTemplate: instanceTemplateName,
+		Project:          instanceTemplateProject,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("getting instance template %q: %w", instanceTemplateName, err)
+	}
+	return instanceTemplate, nil
+}
+
+func instanceTemplateSourceImage(instanceTemplate *computepb.InstanceTemplate) (string, error) {
+	if instanceTemplate.Properties == nil ||
+		len(instanceTemplate.Properties.Disks) == 0 ||
+		instanceTemplate.Properties.Disks[0].InitializeParams == nil ||
+		instanceTemplate.Properties.Disks[0].InitializeParams.SourceImage == nil {
+		return "", errors.New("instance template has no source image")
+	}
+	return uriNormalize(*instanceTemplate.Properties.Disks[0].InitializeParams.SourceImage), nil
+}