[kwokctl] Support for getting default configuration from remote

cmd/kwokctl/main.go

@@ -40,7 +40,14 @@ func main() {
 	ctx := signals.SetupSignalContext()
 	ctx, logger := log.InitFlags(ctx, flagset)
 
-	ctx, err := config.InitFlags(ctx, flagset)
+	err := config.FetchDefaultConfig(ctx)
+	if err != nil {
+		logger.Warn("Fetch default config",
+			"err", err,
+		)
+	}
+
+	ctx, err = config.InitFlags(ctx, flagset)
 	if err != nil {
 		_, _ = os.Stderr.Write([]byte(flagset.FlagUsages()))
 		logger.Error("Init config flags", err)

pkg/config/default_config.go

@@ -0,0 +1,74 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package config
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+
+	"sigs.k8s.io/kwok/pkg/consts"
+	"sigs.k8s.io/kwok/pkg/log"
+	"sigs.k8s.io/kwok/pkg/utils/file"
+	"sigs.k8s.io/kwok/pkg/utils/path"
+)
+
+func FetchDefaultConfig(ctx context.Context) error {
+	fullPath := path.Join(WorkDir, consts.ConfigName)
+	if file.Exists(fullPath) {
+		return nil
+	}
+
+	logger := log.FromContext(ctx)
+
+	logger.Info("Fetch default config from remote",
+		"url", consts.KwokctlDefaultConfigURL,
+		"path", path.RelFromHome(fullPath),
+	)
+
+	err := file.MkdirAll(WorkDir)
+	if err != nil {
+		return err
+	}
+
+	f, err := file.Open(fullPath)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		_ = f.Close()
+	}()
+
+	resp, err := http.Get(consts.KwokctlDefaultConfigURL)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		_ = resp.Body.Close()
+	}()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("status code %d", resp.StatusCode)
+	}
+
+	_, err = io.Copy(f, resp.Body)
+	if err != nil {
+		return err
+	}
+	return nil
+}

pkg/consts/consts.go

@@ -28,6 +28,9 @@ var (
 	BinaryPrefix = "https://github.com/kubernetes-sigs/kwok/releases/download"
 	ImagePrefix  = "registry.k8s.io/kwok"
 
+	// KwokctlDefaultConfigURL is the URL from which kwokctl will fetch the default configuration when started for the first time
+	KwokctlDefaultConfigURL = "https://kwok.sigs.k8s.io/config/0.7/kwok.yaml"
+
 	// PreRelease is the pre-release version of the project.
 	// It will be overwritten during the `make build` process.
 	PreRelease = "alpha"

site/static/config/0.7/kwok.yaml

@@ -0,0 +1,4 @@
+apiVersion: config.kwok.x-k8s.io/v1alpha1
+kind: KwokctlConfiguration
+options:
+  kubeVersion: v1.32.2