[node operator] Add GCP client

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

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

@@ -0,0 +1,29 @@
+package client
+
+import (
+	"fmt"
+	"regexp"
+)
+
+var instanceGroupIDRegex = regexp.MustCompile(`^projects/([^/]+)/zones/([^/]+)/instanceGroupManagers/([^/]+)$`)
+
+// splitInstanceGroupID splits an instance group ID into core components.
+func splitInstanceGroupID(instanceGroupID string) (project, zone, instanceGroup string, err error) {
+	matches := instanceGroupIDRegex.FindStringSubmatch(instanceGroupID)
+	if len(matches) != 4 {
+		return "", "", "", fmt.Errorf("error splitting instanceGroupID: %v", instanceGroupID)
+	}
+	return matches[1], matches[2], matches[3], nil
+}
+
+// generateInstanceName generates a random instance name.
+func generateInstanceName(baseInstanceName string, random prng) (string, error) {
+	letters := []byte("abcdefghijklmnopqrstuvwxyz0123456789")
+	const uidLen = 4
+	uid := make([]byte, 0, uidLen)
+	for i := 0; i < uidLen; i++ {
+		n := random.Intn(len(letters))
+		uid = append(uid, letters[n])
+	}
+	return baseInstanceName + "-" + string(uid), nil
+}