fix(k8s): correct k8s control plane components version using the user specified node image version (#2271)

Author: zdk

Sources/ContainerK8s/Commands/K8sCreate.swift

@@ -68,6 +68,9 @@ public struct K8sCreate: AsyncParsableCommand {
             }
         }
 
+        // Fail before provisioning the node VM.
+        _ = try K8sHelper.kubernetesVersion(nodeImage: nodeImage)
+
         let isTTY = isatty(FileHandle.standardError.fileDescriptor) == 1
         let progressConfig = try ProgressConfig(
             showSpinner: isTTY,
@@ -110,7 +113,7 @@ public struct K8sCreate: AsyncParsableCommand {
             progress.set(description: "Running kubeadm init")
             try await K8sHelper.prepareNode(nodeID: name, client: client, log: log)
             try await K8sHelper.bootstrapControlPlane(
-                nodeID: name, apiServerSANs: sans, advertiseAddress: vmIP,
+                nodeID: name, nodeImage: nodeImage, apiServerSANs: sans, advertiseAddress: vmIP,
                 schedulable: provisioner.roles.contains(StandardRoles.worker),
                 cniManifestPath: cni,
                 client: client, log: log)

Sources/ContainerK8s/Support/K8sHelper+Bootstrap.swift

@@ -34,10 +34,10 @@ extension K8sHelper {
     }
 
     static func bootstrapControlPlane(
-        nodeID: String, apiServerSANs: [String], advertiseAddress: String,
+        nodeID: String, nodeImage: String, apiServerSANs: [String], advertiseAddress: String,
         schedulable: Bool, cniManifestPath: String? = nil, client: ContainerClient, log: Logger
     ) async throws {
-        let configYAML = initConfigYAML(advertiseAddress: advertiseAddress, certSANs: apiServerSANs)
+        let configYAML = try initConfigYAML(nodeImage: nodeImage, advertiseAddress: advertiseAddress, certSANs: apiServerSANs)
         var r = try await execCapture(
             containerId: nodeID, executable: "/bin/sh",
             arguments: ["-c", "cat > /etc/kubernetes/kubeadm-config.yaml <<'EOF'\n\(configYAML)\nEOF"],
@@ -144,7 +144,7 @@ extension K8sHelper {
         """
     }
 
-    private static func initConfigYAML(advertiseAddress: String, certSANs: [String]) -> String {
+    private static func initConfigYAML(nodeImage: String, advertiseAddress: String, certSANs: [String]) throws -> String {
         let sans = certSANs.map { "  - \($0)" }.joined(separator: "\n")
         return """
             apiVersion: kubeadm.k8s.io/v1beta4
@@ -157,7 +157,7 @@ extension K8sHelper {
             ---
             apiVersion: kubeadm.k8s.io/v1beta4
             kind: ClusterConfiguration
-            kubernetesVersion: \(kubernetesVersion())
+            kubernetesVersion: \(try kubernetesVersion(nodeImage: nodeImage))
             networking:
               podSubnet: \(podSubnet)
             apiServer:
@@ -171,9 +171,14 @@ extension K8sHelper {
             """
     }
 
-    private static func kubernetesVersion() -> String {
+    /// kubeadm needs the exact version, and only the tag carries it.
+    static func kubernetesVersion(nodeImage: String) throws -> String {
         let nameAndTag = nodeImage.split(separator: "@").first.map(String.init) ?? nodeImage
-        guard let ref = try? Reference.parse(nameAndTag), let tag = ref.tag else { return "v1.35" }
+        guard let ref = try? Reference.parse(nameAndTag), let tag = ref.tag else {
+            throw ContainerizationError(
+                .invalidArgument,
+                message: "node image \(nodeImage) has no tag; use a tagged image such as docker.io/kindest/node:v1.34.11")
+        }
         return tag
     }
 }

Tests/K8sPluginTests/K8sNodeImageVersionTests.swift

@@ -0,0 +1,52 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2026 Apple Inc. and the container project 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
+//
+//   https://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.
+//===----------------------------------------------------------------------===//
+
+import Testing
+
+@testable import ContainerK8s
+
+struct K8sNodeImageVersionTests {
+    @Test
+    func versionComesFromTheGivenImage() throws {
+        #expect(try K8sHelper.kubernetesVersion(nodeImage: "docker.io/kindest/node:v1.34.11") == "v1.34.11")
+    }
+
+    @Test
+    func versionComesFromTagWhenDigestIsPresent() throws {
+        let image = "docker.io/kindest/node:v1.34.11@sha256:0000000000000000000000000000000000000000000000000000000000000000"
+        #expect(try K8sHelper.kubernetesVersion(nodeImage: image) == "v1.34.11")
+    }
+
+    @Test
+    func defaultImageStillResolves() throws {
+        #expect(try K8sHelper.kubernetesVersion(nodeImage: K8sHelper.nodeImage) == "v1.35.5")
+    }
+
+    @Test
+    func untaggedImageThrows() {
+        #expect(throws: (any Error).self) {
+            try K8sHelper.kubernetesVersion(nodeImage: "docker.io/kindest/node")
+        }
+    }
+
+    @Test
+    func digestOnlyImageThrows() {
+        let image = "docker.io/kindest/node@sha256:0000000000000000000000000000000000000000000000000000000000000000"
+        #expect(throws: (any Error).self) {
+            try K8sHelper.kubernetesVersion(nodeImage: image)
+        }
+    }
+}