Add file provider

Author: ntnn

examples/file/README.md

@@ -0,0 +1,18 @@
+# file
+
+The file provider reads kubeconfig files from the local filesystem.
+
+It provides clusters named after the context name in the kubeconfig file.
+
+This example reads kubeconfig files at the specified paths and lists the
+collected clusters.
+
+## Example
+
+With a single kind cluster defined in `~/.kube/config`:
+
+```bash
+$ go run . -paths ~/.kube/config
+Clusters:
+- kind-kind
+```

examples/file/go.mod

@@ -0,0 +1,52 @@
+module sigs.k8s.io/multicluster-runtime/examples/file
+
+go 1.24.0
+
+replace sigs.k8s.io/multicluster-runtime => ../..
+
+require sigs.k8s.io/multicluster-runtime v0.0.0-00010101000000-000000000000
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/emicklei/go-restful/v3 v3.11.0 // indirect
+	github.com/evanphx/json-patch/v5 v5.9.11 // indirect
+	github.com/fxamacker/cbor/v2 v2.7.0 // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/go-openapi/jsonpointer v0.21.0 // indirect
+	github.com/go-openapi/jsonreference v0.20.2 // indirect
+	github.com/go-openapi/swag v0.23.0 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/google/gnostic-models v0.6.9 // indirect
+	github.com/google/go-cmp v0.7.0 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/josharian/intern v1.0.0 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/mailru/easyjson v0.7.7 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/x448/float16 v0.8.4 // indirect
+	golang.org/x/net v0.38.0 // indirect
+	golang.org/x/oauth2 v0.27.0 // indirect
+	golang.org/x/sys v0.31.0 // indirect
+	golang.org/x/term v0.30.0 // indirect
+	golang.org/x/text v0.23.0 // indirect
+	golang.org/x/time v0.9.0 // indirect
+	google.golang.org/protobuf v1.36.5 // indirect
+	gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect
+	gopkg.in/inf.v0 v0.9.1 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+	k8s.io/api v0.33.0 // indirect
+	k8s.io/apimachinery v0.33.0 // indirect
+	k8s.io/client-go v0.33.0 // indirect
+	k8s.io/klog/v2 v2.130.1 // indirect
+	k8s.io/kube-openapi v0.0.0-20250318190949-c8a335a9a2ff // indirect
+	k8s.io/utils v0.0.0-20241104100929-3ea5e8cea738 // indirect
+	sigs.k8s.io/controller-runtime v0.21.0 // indirect
+	sigs.k8s.io/json v0.0.0-20241010143419-9aa6b5e7a4b3 // indirect
+	sigs.k8s.io/randfill v1.0.0 // indirect
+	sigs.k8s.io/structured-merge-diff/v4 v4.6.0 // indirect
+	sigs.k8s.io/yaml v1.4.0 // indirect
+)

examples/file/go.sum

@@ -0,0 +1,87 @@
+/*
+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 main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"os/signal"
+	"strings"
+	"syscall"
+	"time"
+
+	"sigs.k8s.io/multicluster-runtime/providers/file"
+)
+
+var (
+	fPaths    = flag.String("paths", "", "Comma-separated list of file paths to process (can be files or directories), defaults to current directory")
+	fGlobs    = flag.String("globs", "", "Comma-separated list of glob patterns to match files")
+	fContinue = flag.Bool("continue", false, "Continue processing and listing files until cancelled")
+)
+
+func printClusters(clusters []string) {
+	if len(clusters) == 0 {
+		fmt.Println("No clusters found.")
+		return
+	}
+	fmt.Println("Clusters:")
+	for _, cluster := range clusters {
+		fmt.Printf("- %s\n", cluster)
+	}
+}
+
+func main() {
+	flag.Parse()
+
+	ctx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	defer cancel()
+
+	provider, err := file.New(file.Options{
+		Paths:           strings.Split(*fPaths, ","),
+		KubeconfigGlobs: strings.Split(*fGlobs, ","),
+	})
+	if err != nil {
+		fmt.Printf("Error creating provider: %v\n", err)
+		return
+	}
+
+	if err := provider.RunOnce(ctx); err != nil {
+		fmt.Printf("Error running provider once: %v\n", err)
+		return
+	}
+
+	printClusters(provider.ClusterNames())
+
+	if *fContinue {
+		go func() {
+			if err := provider.Run(ctx); err != nil {
+				fmt.Printf("Error running provider continuously: %v\n", err)
+				return
+			}
+		}()
+
+		for range time.Tick(1 * time.Second) {
+			if ctx.Err() != nil {
+				fmt.Println("Context cancelled, stopping...")
+				break
+			}
+
+			printClusters(provider.ClusterNames())
+		}
+	}
+}

examples/file/main.go

@@ -18,6 +18,7 @@ require (
 	k8s.io/klog/v2 v2.130.1
 	k8s.io/utils v0.0.0-20241104100929-3ea5e8cea738
 	sigs.k8s.io/controller-runtime v0.21.0
+	sigs.k8s.io/randfill v1.0.0
 	sigs.k8s.io/yaml v1.4.0
 )
 
@@ -67,6 +68,5 @@ require (
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	k8s.io/kube-openapi v0.0.0-20250318190949-c8a335a9a2ff // indirect
 	sigs.k8s.io/json v0.0.0-20241010143419-9aa6b5e7a4b3 // indirect
-	sigs.k8s.io/randfill v1.0.0 // indirect
 	sigs.k8s.io/structured-merge-diff/v4 v4.6.0 // indirect
 )

go.mod

@@ -0,0 +1,135 @@
+/*
+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 file
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+
+	"sigs.k8s.io/controller-runtime/pkg/cluster"
+)
+
+type clusters map[string]cluster.Cluster
+
+func (p *Provider) loadClusters() (clusters, error) {
+	filepaths, err := p.collectPaths(p.opts.Paths)
+	if err != nil {
+		return nil, err
+	}
+
+	kubeCtxs := map[string]*rest.Config{}
+	for _, filepath := range filepaths {
+		fileKubeCtxs, err := readFile(filepath)
+		if err != nil {
+			p.log.Error(err, "failed to read kubeconfig file", "file", filepath)
+			continue
+		}
+		for name, kubeCtx := range fileKubeCtxs {
+			if _, exists := kubeCtxs[name]; exists {
+				p.log.Error(nil, "duplicate context name found", "context", name, "file", filepath)
+				continue
+			}
+			kubeCtxs[name] = kubeCtx
+		}
+	}
+
+	return p.fromContexts(kubeCtxs), nil
+}
+
+func (p *Provider) collectPaths(paths []string) ([]string, error) {
+	filepaths := make([]string, 0, len(paths))
+
+	for _, path := range paths {
+		if path == "" {
+			continue
+		}
+
+		stat, err := os.Stat(path)
+		if err != nil {
+			if os.IsNotExist(err) {
+				p.log.Info("path does not exist, skipping", "path", path)
+				continue
+			}
+			return nil, fmt.Errorf("failed to stat path %q: %w", path, err)
+		}
+
+		if !stat.IsDir() {
+			filepaths = append(filepaths, path)
+			continue
+		}
+
+		filepaths = append(filepaths, p.matchKubeconfigGlobs(path)...)
+	}
+
+	return filepaths, nil
+}
+
+func (p *Provider) matchKubeconfigGlobs(dirpath string) []string {
+	matches := []string{}
+
+	for _, glob := range p.opts.KubeconfigGlobs {
+		globMatches, err := filepath.Glob(filepath.Join(dirpath, glob))
+		if err != nil {
+			p.log.Error(err, "failed to glob files", "dirpath", dirpath, "glob", glob)
+			continue
+		}
+		matches = append(matches, globMatches...)
+	}
+
+	return matches
+}
+
+func readFile(filepath string) (map[string]*rest.Config, error) {
+	config, err := clientcmd.LoadFromFile(filepath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to load kubeconfig from file %q: %w", filepath, err)
+	}
+
+	ret := make(map[string]*rest.Config, len(config.Contexts))
+	for name := range config.Contexts {
+		restConfig, err := clientcmd.NewNonInteractiveClientConfig(*config, name, &clientcmd.ConfigOverrides{}, nil).ClientConfig()
+		if err != nil {
+			return nil, fmt.Errorf("failed to create rest config for context %q: %w", name, err)
+		}
+		ret[name] = restConfig
+	}
+
+	return ret, nil
+}
+
+func (p *Provider) fromContexts(kubeCtxs map[string]*rest.Config) clusters {
+	c := make(map[string]cluster.Cluster, len(kubeCtxs))
+
+	for name, kubeCtx := range kubeCtxs {
+		cl, err := cluster.New(kubeCtx)
+		if err != nil {
+			p.log.Error(err, "failed to create cluster", "context", name)
+			continue
+		}
+		if _, ok := c[name]; ok {
+			p.log.Error(nil, "duplicate context name found", "context", name)
+			continue
+		}
+		c[name] = cl
+	}
+
+	return c
+}

providers/file/clusters.go

@@ -0,0 +1,47 @@
+/*
+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 file
+
+import (
+	"testing"
+
+	logf "sigs.k8s.io/controller-runtime/pkg/log"
+	"sigs.k8s.io/controller-runtime/pkg/log/zap"
+	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestBuilder(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "File Provider Suite")
+}
+
+var _ = BeforeSuite(func() {
+	logf.SetLogger(zap.New(zap.WriteTo(GinkgoWriter), zap.UseDevMode(true)))
+
+	// The file provider is designed to work with local files and
+	// directories, so we don't need envtest.
+
+	// Prevent the metrics listener being created
+	metricsserver.DefaultBindAddress = "0"
+})
+
+var _ = AfterSuite(func() {
+	metricsserver.DefaultBindAddress = ":8080"
+})