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feat: support crd isolation and discovery per control plane #6

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Merged
zachsmith1 merged 2 commits into from
Feb 13, 2026
Merged

feat: support crd isolation and discovery per control plane #6

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b6052b0
feat: support crd isolation and discovery per control plane
zachsmith1 Feb 13, 2026
fecda10
fix: dont rely on vendor patch
zachsmith1 Feb 13, 2026
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127 changes: 124 additions & 3 deletions cmd/apiserver/app/config.go
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Original file line number Diff line number Diff line change
Expand Up @@ -18,12 +18,14 @@ package app

import (
"net/http"
"strings"

apiextensionsapiserver "k8s.io/apiextensions-apiserver/pkg/apiserver"
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/apimachinery/pkg/util/wait"
"k8s.io/apiserver/pkg/admission"
namespaceplugin "k8s.io/apiserver/pkg/admission/plugin/namespace/lifecycle"
genericfilters "k8s.io/apiserver/pkg/endpoints/filters"
"k8s.io/apiserver/pkg/registry/generic"
"k8s.io/apiserver/pkg/server"
utilfeature "k8s.io/apiserver/pkg/util/feature"
Expand Down Expand Up @@ -121,6 +123,7 @@ func NewConfig(opts options.CompletedOptions) (*Config, error) {
}
clientPool := mc.NewClientPool(genericConfig.LoopbackClientConfig, mcOpts.PathPrefix, mcOpts.ControlPlaneSegment)
informerPool := mc.NewInformerPoolFromClientPool(clientPool, 0, genericConfig.DrainedNotify())
var crdRuntimeMgr *mcbootstrap.CRDRuntimeManager
systemNamespaceBootstrapper := mcbootstrap.NewSystemNamespaceBootstrapper(mcbootstrap.SystemNamespaceOptions{
ClientForCluster: clientPool.KubeClientForCluster,
Namespaces: opts.SystemNamespaces,
Expand All @@ -138,7 +141,33 @@ func NewConfig(opts options.CompletedOptions) (*Config, error) {
})
genericConfig.BuildHandlerChainFunc = func(h http.Handler, conf *server.Config) http.Handler {
ex := mc.PathExtractor{PathPrefix: mcOpts.PathPrefix, ControlPlaneSegment: mcOpts.ControlPlaneSegment}
return mc.WithClusterRouting(server.DefaultBuildHandlerChain(h, conf), ex, mcOpts)
base := server.DefaultBuildHandlerChain(h, conf)
dispatch := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
cid, _, _ := mc.FromContext(r.Context())
if cid != "" && cid != mcOpts.DefaultCluster && crdRuntimeMgr != nil {
if group, version, ok := apisGroupVersionFromPath(r.URL.Path); ok {
served, err := crdRuntimeMgr.ServesGroupVersion(cid, group, version, genericConfig.DrainedNotify())
if err != nil {
klog.Errorf("mc.crdRuntime lookup failed at kube cluster=%s path=%s err=%v", cid, r.URL.Path, err)
http.Error(w, "cluster CRD runtime unavailable", http.StatusServiceUnavailable)
return
}
if !served {
base.ServeHTTP(w, r)
return
}
if h, err := crdRuntimeMgr.Runtime(cid, genericConfig.DrainedNotify()); err == nil && h != nil {
genericfilters.WithRequestInfo(h, conf.RequestInfoResolver).ServeHTTP(w, r)
return
}
klog.Errorf("mc.crdRuntime unresolved at kube cluster=%s path=%s", cid, r.URL.Path)
http.Error(w, "cluster CRD runtime unavailable", http.StatusServiceUnavailable)
return
}
}
base.ServeHTTP(w, r)
})
return mc.WithClusterRouting(dispatch, ex, mcOpts)
}

authManager := mcauth.NewManager(wait.ContextForChannel(genericConfig.DrainedNotify()), mcauth.Options{
Expand Down Expand Up @@ -280,10 +309,54 @@ func NewConfig(opts options.CompletedOptions) (*Config, error) {
if apiExtensions.GenericConfig.RESTOptionsGetter != nil {
apiExtensions.GenericConfig.RESTOptionsGetter = decorateRESTOptionsGetter("apiextensions", apiExtensions.GenericConfig.RESTOptionsGetter, mcOpts)
}
crdRuntimeMgr = mcbootstrap.NewCRDRuntimeManager(mcbootstrap.CRDRuntimeManagerOptions{
BaseAPIExtensionsConfig: apiExtensions,
PathPrefix: mcOpts.PathPrefix,
ControlPlaneSegment: mcOpts.ControlPlaneSegment,
DefaultCluster: mcOpts.DefaultCluster,
})
prevOnClusterSelected := mcOpts.OnClusterSelected
mcOpts.OnClusterSelected = func(clusterID string) {
if prevOnClusterSelected != nil {
prevOnClusterSelected(clusterID)
}
if clusterID == "" || clusterID == mcOpts.DefaultCluster {
return
}
_, _ = crdRuntimeMgr.Runtime(clusterID, genericConfig.DrainedNotify())
}
// Ensure CRDs are also routed through the multicluster handler
apiExtensions.GenericConfig.BuildHandlerChainFunc = func(h http.Handler, conf *server.Config) http.Handler {
ex := mc.PathExtractor{PathPrefix: mcOpts.PathPrefix, ControlPlaneSegment: mcOpts.ControlPlaneSegment}
return mc.WithClusterRouting(server.DefaultBuildHandlerChain(h, conf), ex, mcOpts)
base := server.DefaultBuildHandlerChain(h, conf)
dispatch := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
cid, _, _ := mc.FromContext(r.Context())
if cid != "" && cid != mcOpts.DefaultCluster {
if group, version, ok := apisGroupVersionFromPath(r.URL.Path); ok {
served, err := crdRuntimeMgr.ServesGroupVersion(cid, group, version, genericConfig.DrainedNotify())
if err != nil {
klog.Errorf("mc.crdRuntime lookup failed at apiextensions cluster=%s path=%s err=%v", cid, r.URL.Path, err)
http.Error(w, "cluster CRD runtime unavailable", http.StatusServiceUnavailable)
return
}
if !served {
base.ServeHTTP(w, r)
return
}
if h, err := crdRuntimeMgr.Runtime(cid, genericConfig.DrainedNotify()); err == nil && h != nil {
// Ensure RequestInfo is computed from the normalized /apis path
// before entering the cluster-scoped CRD runtime handler.
genericfilters.WithRequestInfo(h, conf.RequestInfoResolver).ServeHTTP(w, r)
return
}
klog.Errorf("mc.crdRuntime unresolved cluster=%s path=%s", cid, r.URL.Path)
http.Error(w, "cluster CRD runtime unavailable", http.StatusServiceUnavailable)
return
}
}
base.ServeHTTP(w, r)
})
return mc.WithClusterRouting(dispatch, ex, mcOpts)
}
// Install admission chain on apiextensions as well
{
Expand All @@ -309,7 +382,31 @@ func NewConfig(opts options.CompletedOptions) (*Config, error) {
// Ensure aggregator also receives multicluster routing
aggregator.GenericConfig.BuildHandlerChainFunc = func(h http.Handler, conf *server.Config) http.Handler {
ex := mc.PathExtractor{PathPrefix: mcOpts.PathPrefix, ControlPlaneSegment: mcOpts.ControlPlaneSegment}
return mc.WithClusterRouting(server.DefaultBuildHandlerChain(h, conf), ex, mcOpts)
base := server.DefaultBuildHandlerChain(h, conf)
dispatch := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
cid, _, _ := mc.FromContext(r.Context())
if r.Method == http.MethodGet && cid != "" && cid != mcOpts.DefaultCluster && crdRuntimeMgr != nil {
if group, version, ok := exactAPIsGroupVersionDiscoveryPath(r.URL.Path); ok {
served, err := crdRuntimeMgr.ServesGroupVersion(cid, group, version, genericConfig.DrainedNotify())
if err != nil {
klog.Errorf("mc.crdRuntime lookup failed at aggregator cluster=%s path=%s err=%v", cid, r.URL.Path, err)
http.Error(w, "cluster CRD runtime unavailable", http.StatusServiceUnavailable)
return
}
if served {
if h, err := crdRuntimeMgr.Runtime(cid, genericConfig.DrainedNotify()); err == nil && h != nil {
genericfilters.WithRequestInfo(h, conf.RequestInfoResolver).ServeHTTP(w, r)
return
}
klog.Errorf("mc.crdRuntime unresolved at aggregator cluster=%s path=%s", cid, r.URL.Path)
http.Error(w, "cluster CRD runtime unavailable", http.StatusServiceUnavailable)
return
}
}
}
base.ServeHTTP(w, r)
})
return mc.WithClusterRouting(dispatch, ex, mcOpts)
}
// Install admission chain on aggregator
{
Expand Down Expand Up @@ -338,3 +435,27 @@ func decorateRESTOptionsGetter(server string, getter generic.RESTOptionsGetter,
klog.Infof("mc.restOptionsGetter server=%s decorated=%t", server, true)
return decorated
}

func apisGroupVersionFromPath(path string) (group, version string, ok bool) {
parts := strings.Split(strings.Trim(path, "/"), "/")
if len(parts) < 3 || parts[0] != "apis" || parts[1] == "" || parts[2] == "" {
return "", "", false
}
if parts[1] == "apiextensions.k8s.io" {
return "", "", false
}
return parts[1], parts[2], true
}

func exactAPIsGroupVersionDiscoveryPath(path string) (group, version string, ok bool) {
group, version, ok = apisGroupVersionFromPath(path)
if !ok {
return "", "", false
}
parts := strings.Split(strings.Trim(path, "/"), "/")
if len(parts) != 3 {
return "", "", false
}
return group, version, true
}

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