docs: Add examples of "attach to pod" functionality

README.md

@@ -666,6 +666,7 @@ operations. However, some might require slightly more code to achieve same resul
 | `kubectl run`                                                                      | [PodRunEquivalent.java](./kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/kubectl/equivalents/PodRunEquivalent.java)       |
 | `kubectl create -f test-pod.yaml`                                                  | [PodCreateYamlEquivalent.java](./kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/kubectl/equivalents/PodCreateYamlEquivalent.java)         |
 | `kubectl exec my-pod -- ls /`                                                      | [PodExecEquivalent.java](./kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/kubectl/equivalents/PodExecEquivalent.java) |
+| `kubectl attach my-pod`                                                            | [PodAttachEquivalent.java](./kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/kubectl/equivalents/PodAttachEquivalent.java) |
 | `kubectl delete pod my-pod`                                                        | [PodDelete.java](./kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/kubectl/equivalents/PodDelete.java) |
 | `kubectl delete -f test-pod.yaml`                                                  | [PodDeleteViaYaml.java](./kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/kubectl/equivalents/PodDeleteViaYaml.java) |
 | `kubectl cp /foo_dir my-pod:/bar_dir`                                              | [UploadDirectoryToPod.java](./kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/kubectl/equivalents/UploadDirectoryToPod.java) |

kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/AttachExample.java

@@ -0,0 +1,88 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * 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
+ *
+ *         http://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.
+ */
+package io.fabric8.kubernetes.examples;
+
+import io.fabric8.kubernetes.client.KubernetesClient;
+import io.fabric8.kubernetes.client.KubernetesClientBuilder;
+import io.fabric8.kubernetes.client.dsl.ExecListener;
+import io.fabric8.kubernetes.client.dsl.ExecWatch;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * This is an example of attaching to pod to access stdin, stdout, stderr
+ */
+public class AttachExample {
+
+  public static void main(String[] args) throws IOException {
+    if (args.length < 1) {
+      System.out.println("Usage: podName [namespace]");
+      return;
+    }
+
+    String podName = args[0];
+    String namespace = "default";
+
+    if (args.length > 1) {
+      namespace = args[1];
+    }
+
+    CompletableFuture<Void> sessionFuture = new CompletableFuture<>();
+    try (
+        KubernetesClient client = new KubernetesClientBuilder().build();
+        ExecWatch watch = attach(client, namespace, podName, sessionFuture)) {
+      System.out.println("Type 'exit' to detach");
+      BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
+      while (true) {
+        String input = reader.readLine();
+        if (input.equals("exit")) {
+          return;
+        }
+        watch.getInput().write((input + "\n").getBytes(StandardCharsets.UTF_8));
+        watch.getInput().flush();
+        if (sessionFuture.isDone()) {
+          System.out.println("Session closed");
+          return;
+        }
+      }
+    }
+  }
+
+  private static ExecWatch attach(KubernetesClient client, String namespace, String podName,
+      CompletableFuture<Void> sessionFuture) {
+    return client.pods().inNamespace(namespace).withName(podName)
+        .redirectingInput()
+        .writingOutput(System.out)
+        .writingError(System.err)
+        .withTTY()
+        .usingListener(new ExecListener() {
+          @Override
+          public void onFailure(Throwable t, Response failureResponse) {
+            sessionFuture.complete(null);
+          }
+
+          @Override
+          public void onClose(int code, String reason) {
+            sessionFuture.complete(null);
+          }
+        })
+        .attach();
+  }
+}

kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/kubectl/equivalents/PodAttachEquivalent.java

@@ -0,0 +1,84 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * 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
+ *
+ *         http://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.
+ */
+package io.fabric8.kubernetes.examples.kubectl.equivalents;
+
+import io.fabric8.kubernetes.client.KubernetesClient;
+import io.fabric8.kubernetes.client.KubernetesClientBuilder;
+import io.fabric8.kubernetes.client.dsl.ExecListener;
+import io.fabric8.kubernetes.client.dsl.ExecWatch;
+import lombok.Getter;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * This sample code is Java equivalent to `kubectl attach my-pod`. It assumes that
+ * a Pod with specified name exists in the cluster.
+ */
+public class PodAttachEquivalent {
+
+  private static final Logger logger = LoggerFactory.getLogger(PodAttachEquivalent.class);
+
+  public static void main(String[] args) throws IOException {
+    try (KubernetesClient client = new KubernetesClientBuilder().build()) {
+      MyAttachListener listener = new MyAttachListener();
+      ExecWatch watch = client.pods().inNamespace("default").withName("my-pod")
+          .redirectingInput()
+          .writingOutput(System.out)
+          .writingError(System.err)
+          .withTTY()
+          .usingListener(listener)
+          .attach();
+
+      BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
+      while (!listener.getSessionCompletionFuture().isDone()) {
+        String input = reader.readLine();
+        watch.getInput().write((input + "\n").getBytes(StandardCharsets.UTF_8));
+        watch.getInput().flush();
+      }
+
+      watch.close();
+    }
+  }
+
+  private static class MyAttachListener implements ExecListener {
+
+    @Getter
+    private final CompletableFuture<Void> sessionCompletionFuture = new CompletableFuture<>();
+
+    @Override
+    public void onOpen() {
+      logger.info("Attached to the pod");
+    }
+
+    @Override
+    public void onFailure(Throwable t, Response failureResponse) {
+      logger.warn("Error encountered", t);
+      sessionCompletionFuture.complete(null);
+    }
+
+    @Override
+    public void onClose(int i, String s) {
+      logger.info("Session closed");
+      sessionCompletionFuture.complete(null);
+    }
+  }
+}