Merge pull request #129653 from danwinship/nftables-ga

KEP-3866 nftables kube-proxy to GA

cmd/kube-proxy/app/server_linux.go

@@ -36,13 +36,11 @@ import (
 	"k8s.io/apimachinery/pkg/fields"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/watch"
-	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	clientset "k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/tools/cache"
 	toolswatch "k8s.io/client-go/tools/watch"
 	utilsysctl "k8s.io/component-helpers/node/util/sysctl"
 	"k8s.io/klog/v2"
-	"k8s.io/kubernetes/pkg/features"
 	"k8s.io/kubernetes/pkg/proxy"
 	proxyconfigapi "k8s.io/kubernetes/pkg/proxy/apis/config"
 	"k8s.io/kubernetes/pkg/proxy/iptables"
@@ -527,11 +525,9 @@ func platformCleanup(ctx context.Context, mode proxyconfigapi.ProxyMode, cleanup
 		}
 	}
 
-	if utilfeature.DefaultFeatureGate.Enabled(features.NFTablesProxyMode) {
-		// Clean up nftables rules when switching to iptables or ipvs, or if cleanupAndExit
-		if isIPTablesBased(mode) || cleanupAndExit {
-			encounteredError = nftables.CleanupLeftovers(ctx) || encounteredError
-		}
+	// Clean up nftables rules when switching to iptables or ipvs, or if cleanupAndExit
+	if isIPTablesBased(mode) || cleanupAndExit {
+		encounteredError = nftables.CleanupLeftovers(ctx) || encounteredError
 	}
 
 	if encounteredError {

pkg/features/versioned_kube_features.go

@@ -540,6 +540,7 @@ var defaultVersionedKubernetesFeatureGates = map[featuregate.Feature]featuregate
 	NFTablesProxyMode: {
 		{Version: version.MustParse("1.29"), Default: false, PreRelease: featuregate.Alpha},
 		{Version: version.MustParse("1.31"), Default: true, PreRelease: featuregate.Beta},
+		{Version: version.MustParse("1.33"), Default: true, PreRelease: featuregate.GA, LockToDefault: true},
 	},
 
 	NodeInclusionPolicyInPodTopologySpread: {

pkg/proxy/apis/config/validation/validation.go

@@ -30,7 +30,6 @@ import (
 	logsapi "k8s.io/component-base/logs/api/v1"
 	"k8s.io/component-base/metrics"
 	apivalidation "k8s.io/kubernetes/pkg/apis/core/validation"
-	"k8s.io/kubernetes/pkg/features"
 	kubeproxyconfig "k8s.io/kubernetes/pkg/proxy/apis/config"
 	netutils "k8s.io/utils/net"
 )
@@ -173,12 +172,9 @@ func validateProxyModeLinux(mode kubeproxyconfig.ProxyMode, fldPath *field.Path)
 	validModes := sets.New[string](
 		string(kubeproxyconfig.ProxyModeIPTables),
 		string(kubeproxyconfig.ProxyModeIPVS),
+		string(kubeproxyconfig.ProxyModeNFTables),
 	)
 
-	if utilfeature.DefaultFeatureGate.Enabled(features.NFTablesProxyMode) {
-		validModes.Insert(string(kubeproxyconfig.ProxyModeNFTables))
-	}
-
 	if mode == "" || validModes.Has(string(mode)) {
 		return nil
 	}

pkg/proxy/nftables/README.md

@@ -106,4 +106,34 @@ This is implemented as follows:
     rule for ClusterIPs belonging to any of the ServiceCIDRs in `forward` and `output` hook, with a 
     higher (i.e. less urgent) priority than the DNAT chains making sure all valid
     traffic directed for ClusterIPs is already DNATed. Drop rule will only
-    be installed if `MultiCIDRServiceAllocator` feature is enabled.
+    be installed if `MultiCIDRServiceAllocator` feature is enabled.
+
+## Integrating with kube-proxy's nftables mode
+
+Implementations of pod networking, NetworkPolicy, service meshes, etc, may need to be
+aware of some slightly lower-level details of kube-proxy's implementation.
+
+Components other than kube-proxy should *never* make any modifications to the
+`kube-proxy` nftables table, or any of the chains, sets, maps, etc, within it. Every
+component should create its own table and only work within that table. However,
+you can ensure that rules in your own table will run before or after kube-proxy's rules
+by setting appropriate `priority` values for your base chains. In particular:
+
+  - Service traffic that needs to be DNATted will be DNATted by kube-proxy on a chain of
+    `type nat` with `priority dstnat` and either `hook output` (for traffic on the
+    "output" path) or `hook prerouting` (for traffic on the "input" or "forward" paths).
+    (So chains in other tables that run before this will see traffic addressed to service
+    IPs, while chains that run after this will see traffic addressed to endpoint IPs.)
+
+  - Service traffic that needs to be masqueraded will be SNATted on a chain of `type
+    nat`, `hook postrouting`, and `priority srcnat`. (So chains in other tables that run
+    before this will always see the original client IP, while chains that run after this
+    will will see masqueraded source IPs for some traffic.)
+
+  - Traffic to services with no endpoints will be dropped or rejected from a chain with
+    `type filter`, `priority dstnat-10`, and any of `hook input`, `hook output`, or `hook
+    forward`.
+
+Note that the use of `mark` to indicate what traffic needs to be masqueraded is *not*
+part of kube-proxy's public API, and you should not assume that you can cause traffic to
+be masqueraded (or not) by setting or clearing a particular mark bit.

test/featuregates_linter/test_data/versioned_feature_list.yaml

@@ -842,6 +842,10 @@
     lockToDefault: false
     preRelease: Beta
     version: "1.31"
+  - default: true
+    lockToDefault: true
+    preRelease: GA
+    version: "1.33"
 - name: NodeInclusionPolicyInPodTopologySpread
   versionedSpecs:
   - default: false