Add waitfor logic to test valid restconfig

Signed-off-by: Darren Shepherd <darren@acorn.io>

pkg/restconfig/wait.go

@@ -0,0 +1,45 @@
+package restconfig
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/sirupsen/logrus"
+	"k8s.io/client-go/rest"
+)
+
+func WaitFor(ctx context.Context, cfg *rest.Config) error {
+	ctx, cancel := context.WithTimeout(ctx, 2*time.Minute)
+	defer cancel()
+
+	start := time.Now()
+	log := logrus.WithField("server", cfg.Host)
+	log.Info("Waiting for Kubernetes API to be ready")
+
+	cli, err := rest.UnversionedRESTClientFor(cfg)
+	if err != nil {
+		return err
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			// Return close error along with the last ready error, if any
+			return errors.Join(fmt.Errorf("context closed before %q was ready: %w", cfg.Host, ctx.Err()), err)
+		default:
+		}
+
+		resp := cli.Get().AbsPath("/readyz").Do(ctx)
+		log = log.WithField("elapsed", time.Since(start))
+		if err = resp.Error(); err == nil {
+			log.Info("Kubernetes API ready")
+			break
+		}
+
+		log.WithError(err).Debug("Kubernetes API not ready")
+		time.Sleep(2 * time.Second)
+	}
+	return nil
+}