[node operator] Add GCP client

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

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

@@ -0,0 +1,59 @@
+package client
+
+import (
+	"context"
+	"errors"
+	"net/http"
+
+	"github.com/edgelesssys/constellation/operators/constellation-node-operator/api/v1alpha1"
+	updatev1alpha1 "github.com/edgelesssys/constellation/operators/constellation-node-operator/api/v1alpha1"
+	"google.golang.org/api/googleapi"
+	computepb "google.golang.org/genproto/googleapis/cloud/compute/v1"
+)
+
+// GetNodeState returns the state of the node.
+func (c *Client) GetNodeState(ctx context.Context, providerID string) (updatev1alpha1.CSPNodeState, error) {
+	project, zone, instanceName, err := splitProviderID(providerID)
+	if err != nil {
+		return "", err
+	}
+	instance, err := c.instanceAPI.Get(ctx, &computepb.GetInstanceRequest{
+		Instance: instanceName,
+		Project:  project,
+		Zone:     zone,
+	})
+	if err != nil {
+		var apiErr *googleapi.Error
+		if errors.As(err, &apiErr) {
+			if apiErr.Code == http.StatusNotFound {
+				return v1alpha1.NodeStateTerminated, nil
+			}
+		}
+		return "", err
+	}
+
+	if instance.Status == nil {
+		return v1alpha1.NodeStateUnknown, nil
+	}
+
+	// reference: https://cloud.google.com/compute/docs/instances/instance-life-cycle
+	switch *instance.Status {
+	case computepb.Instance_PROVISIONING.String():
+		fallthrough
+	case computepb.Instance_STAGING.String():
+		return v1alpha1.NodeStateCreating, nil
+	case computepb.Instance_RUNNING.String():
+		return v1alpha1.NodeStateReady, nil
+	case computepb.Instance_STOPPING.String():
+		fallthrough
+	case computepb.Instance_SUSPENDING.String():
+		fallthrough
+	case computepb.Instance_SUSPENDED.String():
+		fallthrough
+	case computepb.Instance_REPAIRING.String():
+		fallthrough
+	case computepb.Instance_TERMINATED.String(): // this is stopped in GCP terms
+		return v1alpha1.NodeStateStopped, nil
+	}
+	return v1alpha1.NodeStateUnknown, nil
+}