Add support for terminal resize in ExecProcess

util/src/main/java/io/kubernetes/client/Exec.java

@@ -611,6 +611,13 @@ public OutputStream getResizeStream() {
       return streamHandler.getOutputStream(4);
     }
 
+    public void resize(int width, int height) throws IOException {
+      OutputStream resizeStream = getResizeStream();
+      String resize = "{ \"width\": " + width + ", \"height\": " + height + " }\n";
+      resizeStream.write(resize.getBytes("UTF-8"));
+      resizeStream.flush();
+    }
+
     private synchronized InputStream getInputStream(int stream) {
       if (!input.containsKey(stream)) {
         input.put(stream, streamHandler.getInputStream(stream));

util/src/main/java/io/kubernetes/client/util/WebSocketStreamHandler.java

@@ -218,6 +218,11 @@ private synchronized OutputStream getSocketInputOutputStream(int stream) {
     return pipedOutput.get(stream);
   }
 
+  // Only used for testing, has to be public because ExecTest is in a different package :(
+  public void injectOutputStream(int streamNum, OutputStream stream) {
+    output.put(streamNum, stream);
+  }
+
   public boolean supportsClose() {
     return this.protocol.equals("v5.channel.k8s.io");
   }

util/src/test/java/io/kubernetes/client/ExecTest.java

@@ -139,6 +139,25 @@ void execProcess() throws IOException, InterruptedException {
     assertThat(process.exitValue()).isZero();
   }
 
+  @Test
+  void terminalResize() throws IOException, InterruptedException {
+    final Throwable throwable = mock(Throwable.class);
+    final ExecProcess process = new ExecProcess(client);
+    ByteArrayOutputStream bos = new ByteArrayOutputStream();
+
+    System.out.println("Injecting output stream");
+    process.getHandler().injectOutputStream(4, bos);
+    System.out.println("Resizing output stream");
+    process.resize(100, 100);
+    System.out.println("Resizing output stream");
+    process.destroy();
+
+    System.out.println("Going to tests.");
+
+    String out = bos.toString("UTF-8");
+    assertThat(out).isEqualTo("{ \"width\": 100, \"height\": 100 }\n");
+  }
+
   @Test
   void defaultUnhandledError() throws IOException, InterruptedException {
     final Throwable throwable = mock(Throwable.class);