Adding a check to test if Tar utility is present in the target container (#974)

* Adding a check to test if Tar utility is present in the target container

* Cleaning up the logic

* Creating a checked exception and flipping the if check

* Adding CopyNotSupportedException to example file

* Changed the code to avoid InterruptedException

Author: sarveshkaushal

examples/src/main/java/io/kubernetes/client/examples/CopyExample.java

@@ -18,6 +18,7 @@
 import io.kubernetes.client.openapi.ApiException;
 import io.kubernetes.client.openapi.Configuration;
 import io.kubernetes.client.util.Config;
+import io.kubernetes.client.util.exception.CopyNotSupportedException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.file.Paths;
@@ -31,7 +32,8 @@
  * <p>From inside $REPO_DIR/examples
  */
 public class CopyExample {
-  public static void main(String[] args) throws IOException, ApiException, InterruptedException {
+  public static void main(String[] args)
+      throws IOException, ApiException, InterruptedException, CopyNotSupportedException {
     String podName = "kube-addon-manager-minikube";
     String namespace = "kube-system";
 

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

@@ -17,6 +17,7 @@
 import io.kubernetes.client.openapi.ApiException;
 import io.kubernetes.client.openapi.Configuration;
 import io.kubernetes.client.openapi.models.V1Pod;
+import io.kubernetes.client.util.exception.CopyNotSupportedException;
 import java.io.BufferedInputStream;
 import java.io.File;
 import java.io.FileInputStream;
@@ -93,12 +94,12 @@ public void copyFileFromPod(
   }
 
   public void copyDirectoryFromPod(V1Pod pod, String srcPath, Path destination)
-      throws ApiException, IOException {
+      throws ApiException, IOException, CopyNotSupportedException {
     copyDirectoryFromPod(pod, null, srcPath, destination);
   }
 
   public void copyDirectoryFromPod(V1Pod pod, String container, String srcPath, Path destination)
-      throws ApiException, IOException {
+      throws ApiException, IOException, CopyNotSupportedException {
     copyDirectoryFromPod(
         pod.getMetadata().getNamespace(),
         pod.getMetadata().getName(),
@@ -108,14 +109,17 @@ public void copyDirectoryFromPod(V1Pod pod, String container, String srcPath, Pa
   }
 
   public void copyDirectoryFromPod(String namespace, String pod, String srcPath, Path destination)
-      throws ApiException, IOException {
+      throws ApiException, IOException, CopyNotSupportedException {
     copyDirectoryFromPod(namespace, pod, null, srcPath, destination);
   }
 
   public void copyDirectoryFromPod(
       String namespace, String pod, String container, String srcPath, Path destination)
-      throws ApiException, IOException {
-    // TODO: Test that 'tar' is present in the container?
+      throws ApiException, IOException, CopyNotSupportedException {
+    // Test that 'tar' is present in the container?
+    if (!isTarPresentInContainer(namespace, pod, container)) {
+      throw new CopyNotSupportedException("Tar is not present in the target container");
+    }
     final Process proc =
         this.exec(
             namespace,
@@ -202,4 +206,20 @@ public void copyFileToPod(
 
     return;
   }
+
+  private boolean isTarPresentInContainer(String namespace, String pod, String container)
+      throws ApiException, IOException {
+    final Process proc =
+        this.exec(
+            namespace, pod, new String[] {"sh", "-c", "tar --version"}, container, false, false);
+    // This will work for POSIX based operating systems
+    try {
+      int status = proc.waitFor();
+      return status == 127 ? false : true;
+    } catch (InterruptedException ex) {
+      throw new IOException(ex);
+    } finally {
+      proc.destroy();
+    }
+  }
 }

util/src/main/java/io/kubernetes/client/util/exception/CopyNotSupportedException.java

@@ -0,0 +1,8 @@
+package io.kubernetes.client.util.exception;
+
+public class CopyNotSupportedException extends Exception {
+
+  public CopyNotSupportedException(String errorMessage) {
+    super(errorMessage);
+  }
+}