✨ Add file provider for kubeconfig on the filesystem

.github/workflows/ci.yml

@@ -27,6 +27,8 @@ jobs:
           - providers/cluster-api
           - examples/cluster-inventory-api
           - providers/cluster-inventory-api
+          - examples/file
+          - providers/file
     name: golangci-lint [${{ matrix.working-directory }}]
     steps:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # tag=v5.0.0

examples/file/README.md

@@ -0,0 +1,51 @@
+# file
+
+The file provider reads kubeconfig files from the local filesystem.
+
+It provides clusters named after the filepath and context name.
+
+This example lists configmaps in the clusters discovered by the file
+provider.
+
+## Example
+
+With a single kind cluster (`kind-kind` defined in `~/.kube/config`:
+
+```bash
+$ go run . -kubeconfig ~/.kube/config
+2025-08-13T11:28:01+02:00       INFO    file-cluster-provider   file cluster provider initialized       {"kubeconfigFiles": ["/home/user/.kube/config"], "kubeconfigDirs": [], "kubeconfigGlobs": [""]}
+2025-08-13T11:28:01+02:00       INFO    controller-runtime.metrics      Starting metrics server
+2025-08-13T11:28:01+02:00       INFO    Starting Controller     {"controller": "multicluster-configmaps", "controllerGroup": "", "controllerKind": "ConfigMap"}
+2025-08-13T11:28:01+02:00       INFO    Starting workers        {"controller": "multicluster-configmaps", "controllerGroup": "", "controllerKind": "ConfigMap", "worker count": 1}
+2025-08-13T11:28:01+02:00       INFO    controller-runtime.metrics      Serving metrics server  {"bindAddress": ":8080", "secure": false}
+2025-08-13T11:28:01+02:00       INFO    file-cluster-provider   adding cluster  {"name": "/home/user/.kube/config+kind-kind"}
+2025-08-13T11:28:01+02:00       INFO    Starting EventSource    {"controller": "multicluster-configmaps", "controllerGroup": "", "controllerKind": "ConfigMap", "source": "func source: 0x172ca20"}
+2025-08-13T11:28:01+02:00       INFO    Reconciling ConfigMap   {"controller": "multicluster-configmaps", "controllerGroup": "", "controllerKind": "ConfigMap", "reconcileID": "7096cf7e-f382-4f22-8d1b-bff768f99c07", "cluster": "/home/user/.kube/config+kind-kind"}
+2025-08-13T11:28:01+02:00       INFO    ConfigMap found {"controller": "multicluster-configmaps", "controllerGroup": "", "controllerKind": "ConfigMap", "reconcileID": "7096cf7e-f382-4f22-8d1b-bff768f99c07", "cluster": "/home/user/.kube/config+kind-kind", "namespace": "default", "name": "kube-root-ca.crt", "cluster": "/home/user/.kube/config+kind-kind"}
+...
+```
+
+Then adding another kind cluster with `kind create cluster --name test`:
+
+```bash
+2025-08-13T11:28:54+02:00       INFO    file-cluster-provider   received fsnotify event {"event": "\"/home/user/.kube/config.lock\": CREATE"}
+2025-08-13T11:28:54+02:00       INFO    file-cluster-provider   received fsnotify event {"event": "\"/home/user/.kube/config\": WRITE"}
+2025-08-13T11:28:54+02:00       INFO    file-cluster-provider   adding cluster  {"name": "/home/user/.kube/config+kind-test"}
+2025-08-13T11:28:54+02:00       INFO    Starting EventSource    {"controller": "multicluster-configmaps", "controllerGroup": "", "controllerKind": "ConfigMap", "source": "func source: 0x172ca20"}
+2025-08-13T11:28:54+02:00       INFO    file-cluster-provider   received fsnotify event {"event": "\"/home/user/.kube/config\": WRITE"}
+2025-08-13T11:28:54+02:00       INFO    file-cluster-provider   received fsnotify event {"event": "\"/home/user/.kube/config.lock\": REMOVE"}
+2025-08-13T11:28:54+02:00       INFO    Reconciling ConfigMap   {"controller": "multicluster-configmaps", "controllerGroup": "", "controllerKind": "ConfigMap", "reconcileID": "9d3e1e4b-b587-49b1-9fcf-a903f4e713f5", "cluster": "/home/user/.kube/config+kind-test"}
+2025-08-13T11:28:54+02:00       INFO    ConfigMap found {"controller": "multicluster-configmaps", "controllerGroup": "", "controllerKind": "ConfigMap", "reconcileID": "9d3e1e4b-b587-49b1-9fcf-a903f4e713f5", "cluster": "/home/user/.kube/config+kind-test", "namespace": "local-path-storage", "name": "local-path-config", "cluster": "/home/user/.kube/config+kind-test"}
+...
+```
+
+Adding new configmaps to either cluster will trigger a reconcile:
+
+```bash
+kubectl --context kind-test create configmap test --from-literal hello=word
+```
+
+```bash
+2025-08-13T11:30:37+02:00       INFO    Reconciling ConfigMap   {"controller": "multicluster-configmaps", "controllerGroup": "", "controllerKind": "ConfigMap", "reconcileID": "56f49ce6-7ff8-4eb9-b3ac-ad7586265c6d", "cluster": "/home/user/.kube/config+kind-test"}
+2025-08-13T11:30:37+02:00       INFO    ConfigMap found {"controller": "multicluster-configmaps", "controllerGroup": "", "controllerKind": "ConfigMap", "reconcileID": "56f49ce6-7ff8-4eb9-b3ac-ad7586265c6d", "cluster": "/home/user/.kube/config+kind-test", "namespace": "default", "name": "test", "cluster": "/home/user/.kube/config+kind-test"}
+```

examples/file/go.mod

@@ -0,0 +1,76 @@
+module sigs.k8s.io/multicluster-runtime/examples/file
+
+go 1.24.0
+
+replace (
+	sigs.k8s.io/multicluster-runtime => ../..
+	sigs.k8s.io/multicluster-runtime/providers/file => ../../providers/file
+)
+
+require (
+	sigs.k8s.io/multicluster-runtime v0.0.0-00010101000000-000000000000
+	sigs.k8s.io/multicluster-runtime/providers/file v0.0.0-00010101000000-000000000000
+)
+
+require (
+	golang.org/x/sync v0.16.0
+	k8s.io/apimachinery v0.33.3
+	sigs.k8s.io/controller-runtime v0.21.0
+)
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	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/fsnotify/fsnotify v1.7.0 // indirect
+	github.com/fxamacker/cbor/v2 v2.7.0 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
+	github.com/go-logr/zapr v1.3.0 // 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/btree v1.1.3 // 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/prometheus/client_golang v1.22.0 // indirect
+	github.com/prometheus/client_model v0.6.1 // indirect
+	github.com/prometheus/common v0.62.0 // indirect
+	github.com/prometheus/procfs v0.15.1 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/x448/float16 v0.8.4 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	go.uber.org/zap v1.27.0 // indirect
+	golang.org/x/net v0.41.0 // indirect
+	golang.org/x/oauth2 v0.27.0 // indirect
+	golang.org/x/sys v0.33.0 // indirect
+	golang.org/x/term v0.32.0 // indirect
+	golang.org/x/text v0.26.0 // indirect
+	golang.org/x/time v0.9.0 // indirect
+	gomodules.xyz/jsonpatch/v2 v2.4.0 // indirect
+	google.golang.org/protobuf v1.36.6 // indirect
+	gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect
+	gopkg.in/fsnotify.v1 v1.4.7 // indirect
+	gopkg.in/inf.v0 v0.9.1 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+	k8s.io/api v0.33.3 // indirect
+	k8s.io/apiextensions-apiserver v0.33.0 // indirect
+	k8s.io/client-go v0.33.3 // 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/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
+)