Support for display secrets (#21)

org.jdrupes.vmoperator.common/src/org/jdrupes/vmoperator/common/Constants.java

@@ -26,6 +26,9 @@ public class Constants {
     /** The Constant APP_NAME. */
     public static final String APP_NAME = "vm-runner";
 
+    /** The Constant COMP_DISPLAY_SECRETS. */
+    public static final String COMP_DISPLAY_SECRET = "display-secret";
+
     /** The Constant VM_OP_NAME. */
     public static final String VM_OP_NAME = "vm-operator";
 

org.jdrupes.vmoperator.common/src/org/jdrupes/vmoperator/common/K8s.java

@@ -44,6 +44,7 @@ import org.yaml.snakeyaml.LoaderOptions;
 import org.yaml.snakeyaml.Yaml;
 import org.yaml.snakeyaml.constructor.SafeConstructor;
 
+// TODO: Auto-generated Javadoc
 /**
  * Helpers for K8s API.
  */
@@ -74,6 +75,35 @@ public class K8s {
         return Optional.empty();
     }
 
+    /**
+     * Returns a new context with the given version as preferred version.
+     *
+     * @param context the context
+     * @param version the version
+     * @return the API resource
+     */
+    public static APIResource preferred(APIResource context, String version) {
+        assert context.getVersions().contains(version);
+        return new APIResource(context.getGroup(),
+            context.getVersions(), version, context.getKind(),
+            context.getNamespaced(), context.getResourcePlural(),
+            context.getResourceSingular());
+    }
+
+    /**
+     * Return a string representation of the context (API resource).
+     *
+     * @param context the context
+     * @return the string
+     */
+    @SuppressWarnings("PMD.UseLocaleWithCaseConversions")
+    public static String toString(APIResource context) {
+        return (Strings.isNullOrEmpty(context.getGroup()) ? ""
+            : context.getGroup() + "/")
+            + context.getPreferredVersion().toUpperCase()
+            + context.getKind();
+    }
+
     /**
      * Convert Yaml to Json.
      *
@@ -156,6 +186,7 @@ public class K8s {
      * @param api the api
      * @param existing the existing
      * @param update the update
+     * @return the t
      * @throws ApiException the api exception
      */
     public static <T extends KubernetesObject, LT extends KubernetesListObject>
@@ -199,8 +230,10 @@ public class K8s {
      *   * If `type` is not set, set it to "Normal"
      *   * If `regarding` is not set, set it to the given object.
      *
+     * @param client the client
+     * @param object the object
      * @param event the event
-     * @throws ApiException 
+     * @throws ApiException the api exception
      */
     @SuppressWarnings("PMD.NPathComplexity")
     public static void createEvent(ApiClient client,

org.jdrupes.vmoperator.common/src/org/jdrupes/vmoperator/common/K8sDynamicStub.java

@@ -18,10 +18,14 @@
 
 package org.jdrupes.vmoperator.common;
 
+import com.google.gson.Gson;
 import io.kubernetes.client.Discovery.APIResource;
 import io.kubernetes.client.apimachinery.GroupVersionKind;
+import io.kubernetes.client.openapi.ApiClient;
 import io.kubernetes.client.openapi.ApiException;
+import io.kubernetes.client.util.generic.options.ListOptions;
 import java.io.Reader;
+import java.util.Collection;
 
 /**
  * A stub for namespaced custom objects. It uses a dynamic model
@@ -47,6 +51,24 @@ public class K8sDynamicStub
             Class<K8sDynamicModels> objectListClass, K8sClient client,
             APIResource context, String namespace, String name) {
         super(objectClass, objectListClass, client, context, namespace, name);
+
+        // Make sure that we have an adapter for our type
+        Gson gson = client.getJSON().getGson();
+        if (!checkAdapters(client)) {
+            client.getJSON().setGson(gson.newBuilder()
+                .registerTypeAdapterFactory(
+                    new K8sDynamicModelTypeAdapterFactory())
+                .create());
+        }
+    }
+
+    private boolean checkAdapters(ApiClient client) {
+        return K8sDynamicModelTypeAdapterFactory.K8sDynamicModelCreator.class
+            .equals(client.getJSON().getGson().getAdapter(K8sDynamicModel.class)
+                .getClass())
+            && K8sDynamicModelTypeAdapterFactory.K8sDynamicModelsCreator.class
+                .equals(client.getJSON().getGson()
+                    .getAdapter(K8sDynamicModels.class).getClass());
     }
 
     /**
@@ -83,8 +105,7 @@ public class K8sDynamicStub
     @SuppressWarnings({ "PMD.AvoidBranchingStatementAsLastInLoop",
         "PMD.AvoidInstantiatingObjectsInLoops", "PMD.UseObjectForClearerAPI" })
     public static K8sDynamicStub get(K8sClient client,
-            APIResource context, String namespace, String name)
-            throws ApiException {
+            APIResource context, String namespace, String name) {
         return K8sGenericStub.get(K8sDynamicModel.class, K8sDynamicModels.class,
             client, context, namespace, name, K8sDynamicStub::new);
     }
@@ -106,4 +127,37 @@ public class K8sDynamicStub
             K8sDynamicModels.class, client, context, model,
             K8sDynamicStub::new);
     }
+
+    /**
+     * Get the stubs for the objects in the given namespace that match
+     * the criteria from the given options.
+     *
+     * @param client the client
+     * @param namespace the namespace
+     * @param options the options
+     * @return the collection
+     * @throws ApiException the api exception
+     */
+    public static Collection<K8sDynamicStub> list(K8sClient client,
+            APIResource context, String namespace, ListOptions options)
+            throws ApiException {
+        return K8sGenericStub.list(K8sDynamicModel.class,
+            K8sDynamicModels.class, client, context, namespace, options,
+            K8sDynamicStub::new);
+    }
+
+    /**
+     * Get the stubs for the objects in the given namespace.
+     *
+     * @param client the client
+     * @param namespace the namespace
+     * @return the collection
+     * @throws ApiException the api exception
+     */
+    public static Collection<K8sDynamicStub> list(K8sClient client,
+            APIResource context, String namespace)
+            throws ApiException {
+        return list(client, context, namespace, new ListOptions());
+    }
+
 }

org.jdrupes.vmoperator.common/src/org/jdrupes/vmoperator/common/K8sGenericStub.java

@@ -18,21 +18,22 @@
 
 package org.jdrupes.vmoperator.common;
 
-import com.google.gson.Gson;
 import io.kubernetes.client.Discovery.APIResource;
 import io.kubernetes.client.apimachinery.GroupVersionKind;
 import io.kubernetes.client.common.KubernetesListObject;
 import io.kubernetes.client.common.KubernetesObject;
 import io.kubernetes.client.custom.V1Patch;
-import io.kubernetes.client.openapi.ApiClient;
 import io.kubernetes.client.openapi.ApiException;
 import io.kubernetes.client.util.Strings;
 import io.kubernetes.client.util.generic.GenericKubernetesApi;
+import io.kubernetes.client.util.generic.options.GetOptions;
 import io.kubernetes.client.util.generic.options.ListOptions;
 import io.kubernetes.client.util.generic.options.PatchOptions;
 import java.net.HttpURLConnection;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.LinkedList;
+import java.util.List;
 import java.util.Optional;
 import java.util.function.Function;
 
@@ -49,145 +50,16 @@ public class K8sGenericStub<O extends KubernetesObject,
         L extends KubernetesListObject> {
     protected final K8sClient client;
     private final GenericKubernetesApi<O, L> api;
-    protected final String group;
-    protected final String version;
-    protected final String kind;
-    protected final String plural;
+    protected final APIResource context;
     protected final String namespace;
     protected final String name;
 
     /**
-     * Get a namespaced object stub. If the version in parameter
-     * `gvk` is an empty string, the stub refers to the first object 
-     * found with matching group and kind. 
-     *
-     * @param <O> the object type
-     * @param <L> the object list type
-     * @param <R> the stub type
-     * @param objectClass the object class
-     * @param objectListClass the object list class
-     * @param client the client
-     * @param gvk the group, version and kind
-     * @param namespace the namespace
-     * @param name the name
-     * @param provider the provider
-     * @return the stub if the object exists
-     * @throws ApiException the api exception
-     */
-    @SuppressWarnings({ "PMD.AvoidBranchingStatementAsLastInLoop",
-        "PMD.AvoidInstantiatingObjectsInLoops" })
-    public static <O extends KubernetesObject, L extends KubernetesListObject,
-            R extends K8sGenericStub<O, L>>
-            R get(Class<O> objectClass, Class<L> objectListClass,
-                    K8sClient client, GroupVersionKind gvk, String namespace,
-                    String name, GenericSupplier<O, L, R> provider)
-                    throws ApiException {
-        var context = K8s.context(client, gvk.getGroup(), gvk.getVersion(),
-            gvk.getKind());
-        if (context.isEmpty()) {
-            throw new ApiException("No known API for " + gvk.getGroup()
-                + "/" + gvk.getVersion() + " " + gvk.getKind());
-        }
-        return provider.get(objectClass, objectListClass, client, context.get(),
-            namespace, name);
-    }
-
-    /**
-     * Get a namespaced object stub.
-     *
-     * @param <O> the object type
-     * @param <L> the object list type
-     * @param <R> the stub type
-     * @param objectClass the object class
-     * @param objectListClass the object list class
-     * @param client the client
-     * @param context the context
-     * @param namespace the namespace
-     * @param name the name
-     * @param provider the provider
-     * @return the stub if the object exists
-     * @throws ApiException the api exception
-     */
-    @SuppressWarnings({ "PMD.AvoidBranchingStatementAsLastInLoop",
-        "PMD.AvoidInstantiatingObjectsInLoops", "PMD.UseObjectForClearerAPI" })
-    public static <O extends KubernetesObject, L extends KubernetesListObject,
-            R extends K8sGenericStub<O, L>>
-            R get(Class<O> objectClass, Class<L> objectListClass,
-                    K8sClient client, APIResource context, String namespace,
-                    String name, GenericSupplier<O, L, R> provider)
-                    throws ApiException {
-        return provider.get(objectClass, objectListClass, client,
-            context, namespace, name);
-    }
-
-    /**
-     * Get a namespaced object stub for a newly created object.
-     *
-     * @param <O> the object type
-     * @param <L> the object list type
-     * @param <R> the stub type
-     * @param objectClass the object class
-     * @param objectListClass the object list class
-     * @param client the client
-     * @param context the context
-     * @param model the model
-     * @param provider the provider
-     * @return the stub if the object exists
-     * @throws ApiException the api exception
-     */
-    @SuppressWarnings({ "PMD.AvoidBranchingStatementAsLastInLoop",
-        "PMD.AvoidInstantiatingObjectsInLoops", "PMD.UseObjectForClearerAPI" })
-    public static <O extends KubernetesObject, L extends KubernetesListObject,
-            R extends K8sGenericStub<O, L>>
-            R create(Class<O> objectClass, Class<L> objectListClass,
-                    K8sClient client, APIResource context, O model,
-                    GenericSupplier<O, L, R> provider) throws ApiException {
-        var api = new GenericKubernetesApi<>(objectClass, objectListClass,
-            context.getGroup(), context.getPreferredVersion(),
-            context.getResourcePlural(), client);
-        api.create(model).throwsApiException();
-        return provider.get(objectClass, objectListClass, client,
-            context, model.getMetadata().getNamespace(),
-            model.getMetadata().getName());
-    }
-
-    /**
-     * Get the stubs for the objects in the given namespace that match
-     * the criteria from the given options.
-     *
-     * @param <O> the object type
-     * @param <L> the object list type
-     * @param <R> the stub type
-     * @param objectClass the object class
-     * @param objectListClass the object list class
-     * @param client the client
-     * @param context the context
-     * @param namespace the namespace
-     * @param options the options
-     * @param provider the provider
-     * @return the collection
-     * @throws ApiException the api exception
-     */
-    public static <O extends KubernetesObject, L extends KubernetesListObject,
-            R extends K8sGenericStub<O, L>>
-            Collection<R> list(Class<O> objectClass, Class<L> objectListClass,
-                    K8sClient client, APIResource context, String namespace,
-                    ListOptions options, SpecificSupplier<O, L, R> provider)
-                    throws ApiException {
-        var api = new GenericKubernetesApi<>(objectClass, objectListClass,
-            context.getGroup(), context.getPreferredVersion(),
-            context.getResourcePlural(), client);
-        var objs = api.list(namespace, options).throwsApiException();
-        var result = new ArrayList<R>();
-        for (var item : objs.getObject().getItems()) {
-            result.add(
-                provider.get(client, namespace, item.getMetadata().getName()));
-        }
-        return result;
-    }
-
-    /**
-     * Instantiates a new namespaced custom object stub.
+     * Instantiates a new stub for the object specified. If the object
+     * exists in the context specified, the version (see
+     * {@link #version()} is bound to the existing object's version.
+     * Else the stub is dangling with the version set to the context's
+     * preferred version.
      *
      * @param objectClass the object class
      * @param objectListClass the object list class
@@ -196,35 +68,47 @@ public class K8sGenericStub<O extends KubernetesObject,
      * @param namespace the namespace
      * @param name the name
      */
+    @SuppressWarnings("PMD.AvoidInstantiatingObjectsInLoops")
     protected K8sGenericStub(Class<O> objectClass, Class<L> objectListClass,
             K8sClient client, APIResource context, String namespace,
             String name) {
         this.client = client;
-        group = context.getGroup();
-        version = context.getPreferredVersion();
-        kind = context.getKind();
-        plural = context.getResourcePlural();
         this.namespace = namespace;
         this.name = name;
 
-        Gson gson = client.getJSON().getGson();
-        if (!checkAdapters(client)) {
-            client.getJSON().setGson(gson.newBuilder()
-                .registerTypeAdapterFactory(
-                    new K8sDynamicModelTypeAdapterFactory())
-                .create());
+        // Bind version
+        var foundVersion = context.getPreferredVersion();
+        GenericKubernetesApi<O, L> testApi = null;
+        GetOptions mdOpts
+            = new GetOptions().isPartialObjectMetadataRequest(true);
+        for (var version : candidateVersions(context)) {
+            testApi = new GenericKubernetesApi<>(objectClass, objectListClass,
+                context.getGroup(), version, context.getResourcePlural(),
+                client);
+            if (testApi.get(namespace, name, mdOpts)
+                .isSuccess()) {
+                foundVersion = version;
+                break;
+            }
         }
-        api = new GenericKubernetesApi<>(objectClass,
-            objectListClass, group, version, plural, client);
+        if (foundVersion.equals(context.getPreferredVersion())) {
+            this.context = context;
+        } else {
+            this.context = K8s.preferred(context, foundVersion);
+        }
+
+        api = Optional.ofNullable(testApi)
+            .orElseGet(() -> new GenericKubernetesApi<>(objectClass,
+                objectListClass, group(), version(), plural(), client));
     }
 
-    private boolean checkAdapters(ApiClient client) {
-        return K8sDynamicModelTypeAdapterFactory.K8sDynamicModelCreator.class
-            .equals(client.getJSON().getGson().getAdapter(K8sDynamicModel.class)
-                .getClass())
-            && K8sDynamicModelTypeAdapterFactory.K8sDynamicModelsCreator.class
-                .equals(client.getJSON().getGson()
-                    .getAdapter(K8sDynamicModels.class).getClass());
+    /**
+     * Gets the context.
+     *
+     * @return the context
+     */
+    public APIResource context() {
+        return context;
     }
 
     /**
@@ -233,7 +117,7 @@ public class K8sGenericStub<O extends KubernetesObject,
      * @return the group
      */
     public String group() {
-        return group;
+        return context.getGroup();
     }
 
     /**
@@ -242,7 +126,7 @@ public class K8sGenericStub<O extends KubernetesObject,
      * @return the version
      */
     public String version() {
-        return version;
+        return context.getPreferredVersion();
     }
 
     /**
@@ -251,7 +135,7 @@ public class K8sGenericStub<O extends KubernetesObject,
      * @return the kind
      */
     public String kind() {
-        return kind;
+        return context.getKind();
     }
 
     /**
@@ -260,7 +144,7 @@ public class K8sGenericStub<O extends KubernetesObject,
      * @return the plural
      */
     public String plural() {
-        return plural;
+        return context.getResourcePlural();
     }
 
     /**
@@ -387,32 +271,149 @@ public class K8sGenericStub<O extends KubernetesObject,
                 APIResource context, String namespace, String name);
     }
 
-    /**
-     * A supplier for specific stubs.
-     *
-     * @param <O> the object type
-     * @param <L> the object list type
-     * @param <R> the result type
-     */
-    public interface SpecificSupplier<O extends KubernetesObject,
-            L extends KubernetesListObject, R extends K8sGenericStub<O, L>> {
-
-        /**
-         * Gets a new stub.
-         *
-         * @param client the client
-         * @param namespace the namespace
-         * @param name the name
-         * @return the result
-         */
-        R get(K8sClient client, String namespace, String name);
-    }
-
     @Override
     @SuppressWarnings("PMD.UseLocaleWithCaseConversions")
     public String toString() {
-        return (Strings.isNullOrEmpty(group) ? "" : group + "/")
-            + version.toUpperCase() + kind + " " + namespace + ":" + name;
+        return (Strings.isNullOrEmpty(group()) ? "" : group() + "/")
+            + version().toUpperCase() + kind() + " " + namespace + ":" + name;
+    }
+
+    /**
+     * Get a namespaced object stub. If the version in parameter
+     * `gvk` is an empty string, the stub refers to the first object 
+     * found with matching group and kind. 
+     *
+     * @param <O> the object type
+     * @param <L> the object list type
+     * @param <R> the stub type
+     * @param objectClass the object class
+     * @param objectListClass the object list class
+     * @param client the client
+     * @param gvk the group, version and kind
+     * @param namespace the namespace
+     * @param name the name
+     * @param provider the provider
+     * @return the stub if the object exists
+     * @throws ApiException the api exception
+     */
+    @SuppressWarnings({ "PMD.AvoidBranchingStatementAsLastInLoop" })
+    public static <O extends KubernetesObject, L extends KubernetesListObject,
+            R extends K8sGenericStub<O, L>>
+            R get(Class<O> objectClass, Class<L> objectListClass,
+                    K8sClient client, GroupVersionKind gvk, String namespace,
+                    String name, GenericSupplier<O, L, R> provider)
+                    throws ApiException {
+        var context = K8s.context(client, gvk.getGroup(), gvk.getVersion(),
+            gvk.getKind());
+        if (context.isEmpty()) {
+            throw new ApiException("No known API for " + gvk.getGroup()
+                + "/" + gvk.getVersion() + " " + gvk.getKind());
+        }
+        return provider.get(objectClass, objectListClass, client, context.get(),
+            namespace, name);
+    }
+
+    /**
+     * Get a namespaced object stub.
+     *
+     * @param <O> the object type
+     * @param <L> the object list type
+     * @param <R> the stub type
+     * @param objectClass the object class
+     * @param objectListClass the object list class
+     * @param client the client
+     * @param context the context
+     * @param namespace the namespace
+     * @param name the name
+     * @param provider the provider
+     * @return the stub if the object exists
+     * @throws ApiException the api exception
+     */
+    @SuppressWarnings({ "PMD.AvoidBranchingStatementAsLastInLoop",
+        "PMD.UseObjectForClearerAPI" })
+    public static <O extends KubernetesObject, L extends KubernetesListObject,
+            R extends K8sGenericStub<O, L>>
+            R get(Class<O> objectClass, Class<L> objectListClass,
+                    K8sClient client, APIResource context, String namespace,
+                    String name, GenericSupplier<O, L, R> provider) {
+        return provider.get(objectClass, objectListClass, client,
+            context, namespace, name);
+    }
+
+    /**
+     * Get a namespaced object stub for a newly created object.
+     *
+     * @param <O> the object type
+     * @param <L> the object list type
+     * @param <R> the stub type
+     * @param objectClass the object class
+     * @param objectListClass the object list class
+     * @param client the client
+     * @param context the context
+     * @param model the model
+     * @param provider the provider
+     * @return the stub if the object exists
+     * @throws ApiException the api exception
+     */
+    @SuppressWarnings({ "PMD.AvoidBranchingStatementAsLastInLoop",
+        "PMD.AvoidInstantiatingObjectsInLoops", "PMD.UseObjectForClearerAPI" })
+    public static <O extends KubernetesObject, L extends KubernetesListObject,
+            R extends K8sGenericStub<O, L>>
+            R create(Class<O> objectClass, Class<L> objectListClass,
+                    K8sClient client, APIResource context, O model,
+                    GenericSupplier<O, L, R> provider) throws ApiException {
+        var api = new GenericKubernetesApi<>(objectClass, objectListClass,
+            context.getGroup(), context.getPreferredVersion(),
+            context.getResourcePlural(), client);
+        api.create(model).throwsApiException();
+        return provider.get(objectClass, objectListClass, client,
+            context, model.getMetadata().getNamespace(),
+            model.getMetadata().getName());
+    }
+
+    /**
+     * Get the stubs for the objects in the given namespace that match
+     * the criteria from the given options.
+     *
+     * @param <O> the object type
+     * @param <L> the object list type
+     * @param <R> the stub type
+     * @param objectClass the object class
+     * @param objectListClass the object list class
+     * @param client the client
+     * @param context the context
+     * @param namespace the namespace
+     * @param options the options
+     * @param provider the provider
+     * @return the collection
+     * @throws ApiException the api exception
+     */
+    public static <O extends KubernetesObject, L extends KubernetesListObject,
+            R extends K8sGenericStub<O, L>>
+            Collection<R> list(Class<O> objectClass, Class<L> objectListClass,
+                    K8sClient client, APIResource context, String namespace,
+                    ListOptions options, GenericSupplier<O, L, R> provider)
+                    throws ApiException {
+        var result = new ArrayList<R>();
+        for (var version : candidateVersions(context)) {
+            @SuppressWarnings("PMD.AvoidInstantiatingObjectsInLoops")
+            var api = new GenericKubernetesApi<>(objectClass, objectListClass,
+                context.getGroup(), version, context.getResourcePlural(),
+                client);
+            var objs = api.list(namespace, options).throwsApiException();
+            for (var item : objs.getObject().getItems()) {
+                result.add(provider.get(objectClass, objectListClass, client,
+                    context, namespace, item.getMetadata().getName()));
+            }
+        }
+        return result;
+    }
+
+    private static List<String> candidateVersions(APIResource context) {
+        var result = new LinkedList<>(context.getVersions());
+        result.remove(context.getPreferredVersion());
+        result.add(0, context.getPreferredVersion());
+        return result;
     }
 
 }

org.jdrupes.vmoperator.common/src/org/jdrupes/vmoperator/common/K8sObserver.java

@@ -0,0 +1,230 @@
+/*
+ * VM-Operator
+ * Copyright (C) 2024 Michael N. Lipp
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.jdrupes.vmoperator.common;
+
+import io.kubernetes.client.Discovery.APIResource;
+import io.kubernetes.client.common.KubernetesListObject;
+import io.kubernetes.client.common.KubernetesObject;
+import io.kubernetes.client.openapi.ApiException;
+import io.kubernetes.client.util.Watch.Response;
+import io.kubernetes.client.util.generic.GenericKubernetesApi;
+import io.kubernetes.client.util.generic.options.ListOptions;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.function.BiConsumer;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * An observer that watches namespaced resources in a given context and
+ * invokes a handler on changes.
+ *
+ * @param <O> the object type for the context
+ * @param <L> the object list type for the context
+ */
+public class K8sObserver<O extends KubernetesObject,
+        L extends KubernetesListObject> {
+
+    /**
+     * The type of change reported by {@link Response} as enum.
+     */
+    public enum ResponseType {
+        ADDED, MODIFIED, DELETED
+    }
+
+    @SuppressWarnings("PMD.FieldNamingConventions")
+    protected final Logger logger = Logger.getLogger(getClass().getName());
+
+    protected final K8sClient client;
+    protected final GenericKubernetesApi<O, L> api;
+    protected final APIResource context;
+    protected final String namespace;
+    protected final ListOptions options;
+    protected final Thread thread;
+    protected BiConsumer<K8sClient, Response<O>> handler;
+    protected BiConsumer<K8sObserver<O, L>, Throwable> onTerminated;
+
+    /**
+     * Create and start a new observer for objects in the given context 
+     * (using preferred version) and namespace with the given options.
+     *
+     * @param objectClass the object class
+     * @param objectListClass the object list class
+     * @param client the client
+     * @param context the context
+     * @param namespace the namespace
+     * @param options the options
+     */
+    @SuppressWarnings({ "PMD.AvoidBranchingStatementAsLastInLoop",
+        "PMD.UseObjectForClearerAPI", "PMD.AvoidCatchingThrowable",
+        "PMD.CognitiveComplexity" })
+    public K8sObserver(Class<O> objectClass, Class<L> objectListClass,
+            K8sClient client, APIResource context, String namespace,
+            ListOptions options) {
+        this.client = client;
+        this.context = context;
+        this.namespace = namespace;
+        this.options = options;
+
+        api = new GenericKubernetesApi<>(objectClass, objectListClass,
+            context.getGroup(), context.getPreferredVersion(),
+            context.getResourcePlural(), client);
+        thread = new Thread(() -> {
+            try {
+                logger.info(() -> "Watching " + context.getResourcePlural()
+                    + " (" + context.getPreferredVersion() + ")"
+                    + " in " + namespace);
+
+                // Watch sometimes terminates without apparent reason.
+                while (!Thread.currentThread().isInterrupted()) {
+                    Instant startedAt = Instant.now();
+                    try {
+                        @SuppressWarnings("PMD.AvoidInstantiatingObjectsInLoops")
+                        var changed = api.watch(namespace, options).iterator();
+                        while (changed.hasNext()) {
+                            handler.accept(client, changed.next());
+                        }
+                    } catch (ApiException e) {
+                        logger.log(Level.FINE, e, () -> "Problem watching"
+                            + " (will retry): " + e.getMessage());
+                        delayRestart(startedAt);
+                    }
+                }
+                if (onTerminated != null) {
+                    onTerminated.accept(this, null);
+                }
+            } catch (Throwable e) {
+                logger.log(Level.SEVERE, e, () -> "Probem watching: "
+                    + e.getMessage());
+                if (onTerminated != null) {
+                    onTerminated.accept(this, e);
+                }
+            }
+        });
+        thread.setDaemon(true);
+    }
+
+    @SuppressWarnings("PMD.AvoidLiteralsInIfCondition")
+    private void delayRestart(Instant started) {
+        var runningFor = Duration
+            .between(started, Instant.now()).toMillis();
+        if (runningFor < 5000) {
+            logger.log(Level.FINE, () -> "Waiting... ");
+            try {
+                Thread.sleep(5000 - runningFor);
+            } catch (InterruptedException e1) { // NOPMD
+                // Retry
+            }
+            logger.log(Level.FINE, () -> "Retrying");
+        }
+    }
+
+    /**
+     * Sets the handler.
+     *
+     * @param handler the handler
+     * @return the observer
+     */
+    public K8sObserver<O, L>
+            handler(BiConsumer<K8sClient, Response<O>> handler) {
+        this.handler = handler;
+        return this;
+    }
+
+    /**
+     * Sets a function to invoke if the observer terminates. First argument
+     * is this observer, the second is the throwable that caused the
+     * abnormal termination or `null` if the observer was terminated
+     * by {@link #stop()}.
+     *
+     * @param onTerminated the on terminated
+     * @return the observer
+     */
+    public K8sObserver<O, L> onTerminated(
+            BiConsumer<K8sObserver<O, L>, Throwable> onTerminated) {
+        this.onTerminated = onTerminated;
+        return this;
+    }
+
+    /**
+     * Start the observer.
+     *
+     * @return the observer
+     */
+    public K8sObserver<O, L> start() {
+        if (handler == null) {
+            throw new IllegalStateException("No handler defined");
+        }
+        thread.start();
+        return this;
+    }
+
+    /**
+     * Stops the observer.
+     *
+     * @return the observer
+     */
+    public K8sObserver<O, L> stop() {
+        thread.interrupt();
+        return this;
+    }
+
+    /**
+     * Returns the client.
+     *
+     * @return the client
+     */
+    public K8sClient client() {
+        return client;
+    }
+
+    /**
+     * Returns the context.
+     * 
+     * @return the context
+     */
+    public APIResource context() {
+        return context;
+    }
+
+    /**
+     * Returns the observed namespace.
+     * 
+     * @return the namespace
+     */
+    public String getNamespace() {
+        return namespace;
+    }
+
+    /**
+     * Returns the options for object selection.
+     *
+     * @return the list options
+     */
+    public ListOptions options() {
+        return options;
+    }
+
+    @Override
+    @SuppressWarnings("PMD.UseLocaleWithCaseConversions")
+    public String toString() {
+        return "Observer for " + K8s.toString(context) + " " + namespace;
+    }
+
+}

org.jdrupes.vmoperator.common/src/org/jdrupes/vmoperator/common/K8sV1ConfigMapStub.java

@@ -30,6 +30,9 @@ import java.util.List;
 public class K8sV1ConfigMapStub
         extends K8sGenericStub<V1ConfigMap, V1ConfigMapList> {
 
+    public static final APIResource CONTEXT = new APIResource("", List.of("v1"),
+        "v1", "ConfigMap", true, "configmaps", "configmap");
+
     /**
      * Instantiates a new stub.
      *
@@ -40,9 +43,7 @@ public class K8sV1ConfigMapStub
     protected K8sV1ConfigMapStub(K8sClient client, String namespace,
             String name) {
         super(V1ConfigMap.class, V1ConfigMapList.class, client,
-            new APIResource("", List.of("v1"), "v1", "ConfigMap", true,
-                "configmaps", "configmap"),
-            namespace, name);
+            CONTEXT, namespace, name);
     }
 
     /**

org.jdrupes.vmoperator.common/src/org/jdrupes/vmoperator/common/K8sV1DeploymentStub.java

@@ -33,6 +33,10 @@ import java.util.Optional;
 public class K8sV1DeploymentStub
         extends K8sGenericStub<V1Deployment, V1DeploymentList> {
 
+    /** The deployment's context. */
+    public static final APIResource CONTEXT = new APIResource("apps",
+        List.of("v1"), "v1", "Pod", true, "deployments", "deployment");
+
     /**
      * Instantiates a new stub.
      *
@@ -43,22 +47,7 @@ public class K8sV1DeploymentStub
     protected K8sV1DeploymentStub(K8sClient client, String namespace,
             String name) {
         super(V1Deployment.class, V1DeploymentList.class, client,
-            new APIResource("apps", List.of("v1"), "v1", "Pod", true,
-                "deployments", "deployment"),
-            namespace, name);
-    }
-
-    /**
-     * Gets the stub for the given namespace and name.
-     *
-     * @param client the client
-     * @param namespace the namespace
-     * @param name the name
-     * @return the deployment stub
-     */
-    public static K8sV1DeploymentStub get(K8sClient client, String namespace,
-            String name) {
-        return new K8sV1DeploymentStub(client, namespace, name);
+            CONTEXT, namespace, name);
     }
 
     /**
@@ -74,4 +63,17 @@ public class K8sV1DeploymentStub
                 + "\", \"value\": " + replicas + "}]"),
             client.defaultPatchOptions());
     }
+
+    /**
+     * Gets the stub for the given namespace and name.
+     *
+     * @param client the client
+     * @param namespace the namespace
+     * @param name the name
+     * @return the deployment stub
+     */
+    public static K8sV1DeploymentStub get(K8sClient client, String namespace,
+            String name) {
+        return new K8sV1DeploymentStub(client, namespace, name);
+    }
 }

org.jdrupes.vmoperator.common/src/org/jdrupes/vmoperator/common/K8sV1PodStub.java

@@ -32,6 +32,7 @@ import java.util.List;
 @SuppressWarnings("PMD.DataflowAnomalyAnalysis")
 public class K8sV1PodStub extends K8sGenericStub<V1Pod, V1PodList> {
 
+    /** The pods' context. */
     public static final APIResource CONTEXT
         = new APIResource("", List.of("v1"), "v1", "Pod", true, "pods", "pod");
 
@@ -72,7 +73,17 @@ public class K8sV1PodStub extends K8sGenericStub<V1Pod, V1PodList> {
     public static Collection<K8sV1PodStub> list(K8sClient client,
             String namespace, ListOptions options) throws ApiException {
         return K8sGenericStub.list(V1Pod.class, V1PodList.class, client,
-            CONTEXT, namespace, options, K8sV1PodStub::new);
+            CONTEXT, namespace, options, K8sV1PodStub::getGeneric);
+    }
+
+    /**
+     * Provide {@link GenericSupplier}.
+     */
+    @SuppressWarnings("PMD.UnusedFormalParameter")
+    private static K8sV1PodStub getGeneric(Class<V1Pod> objectClass,
+            Class<V1PodList> objectListClass, K8sClient client,
+            APIResource context, String namespace, String name) {
+        return new K8sV1PodStub(client, namespace, name);
     }
 
 }

org.jdrupes.vmoperator.common/src/org/jdrupes/vmoperator/common/K8sV1SecretStub.java

@@ -0,0 +1,60 @@
+/*
+ * VM-Operator
+ * Copyright (C) 2024 Michael N. Lipp
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.jdrupes.vmoperator.common;
+
+import io.kubernetes.client.Discovery.APIResource;
+import io.kubernetes.client.openapi.models.V1Secret;
+import io.kubernetes.client.openapi.models.V1SecretList;
+import java.util.List;
+
+/**
+ * A stub for secrets (v1).
+ */
+@SuppressWarnings("PMD.DataflowAnomalyAnalysis")
+public class K8sV1SecretStub extends K8sGenericStub<V1Secret, V1SecretList> {
+
+    public static final APIResource CONTEXT = new APIResource("", List.of("v1"),
+        "v1", "Secret", true, "secrets", "secret");
+
+    /**
+     * Instantiates a new stub.
+     *
+     * @param client the client
+     * @param namespace the namespace
+     * @param name the name
+     */
+    protected K8sV1SecretStub(K8sClient client, String namespace,
+            String name) {
+        super(V1Secret.class, V1SecretList.class, client,
+            CONTEXT, namespace, name);
+    }
+
+    /**
+     * Gets the stub for the given namespace and name.
+     *
+     * @param client the client
+     * @param namespace the namespace
+     * @param name the name
+     * @return the config map stub
+     */
+    public static K8sV1SecretStub get(K8sClient client, String namespace,
+            String name) {
+        return new K8sV1SecretStub(client, namespace, name);
+    }
+}

org.jdrupes.vmoperator.common/src/org/jdrupes/vmoperator/common/K8sV1StatefulSetStub.java

@@ -30,6 +30,11 @@ import java.util.List;
 public class K8sV1StatefulSetStub
         extends K8sGenericStub<V1StatefulSet, V1StatefulSetList> {
 
+    /** The stateful sets' context */
+    public static final APIResource CONTEXT
+        = new APIResource("apps", List.of("v1"), "v1", "StatefulSet", true,
+            "statefulsets", "statefulset");
+
     /**
      * Instantiates a new stub.
      *
@@ -39,9 +44,7 @@ public class K8sV1StatefulSetStub
      */
     protected K8sV1StatefulSetStub(K8sClient client, String namespace,
             String name) {
-        super(V1StatefulSet.class, V1StatefulSetList.class, client,
-            new APIResource("apps", List.of("v1"), "v1", "StatefulSet", true,
-                "statefulsets", "statefulset"),
+        super(V1StatefulSet.class, V1StatefulSetList.class, client, CONTEXT,
             namespace, name);
     }