[node operator] Add GCP client

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

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

@@ -0,0 +1,47 @@
+package client
+
+import (
+	"fmt"
+	"math"
+	"regexp"
+	"strconv"
+)
+
+var (
+	numberedNameRegex       = regexp.MustCompile(`^(.+)-(\d+)$`)
+	instanceTemplateIDRegex = regexp.MustCompile(`projects/([^/]+)/global/instanceTemplates/([^/]+)`)
+)
+
+// generateInstanceTemplateName generates a unique name for an instance template by incrementing a counter.
+// The name is in the format <prefix>-<counter>.
+func generateInstanceTemplateName(last string) (string, error) {
+	if len(last) > 0 && last[len(last)-1] == '-' {
+		return last + "1", nil
+	}
+	matches := numberedNameRegex.FindStringSubmatch(last)
+	if len(matches) != 3 {
+		return last + "-1", nil
+	}
+	n, err := strconv.Atoi(matches[2])
+	if err != nil {
+		return "", err
+	}
+	if n < 1 || n == math.MaxInt {
+		return "", fmt.Errorf("invalid counter: %v", n)
+	}
+	return matches[1] + "-" + strconv.Itoa(n+1), nil
+}
+
+// splitInstanceTemplateID splits an instance template ID into its project and name components.
+func splitInstanceTemplateID(instanceTemplateID string) (project, templateName string, err error) {
+	matches := instanceTemplateIDRegex.FindStringSubmatch(instanceTemplateID)
+	if len(matches) != 3 {
+		return "", "", fmt.Errorf("error splitting instanceTemplateID: %v", instanceTemplateID)
+	}
+	return matches[1], matches[2], nil
+}
+
+// joinInstanceTemplateURI joins a project and template name into an instance template URI.
+func joinInstanceTemplateURI(project, templateName string) string {
+	return fmt.Sprintf("https://www.googleapis.com/compute/v1/projects/%v/global/instanceTemplates/%v", project, templateName)
+}