YARN-8329. Docker client configuration can still be set incorrectly. Contributed by Shane Kumpf

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/DockerClientConfigHandler.java

@@ -154,14 +154,15 @@ public final class DockerClientConfigHandler {
    * @param outConfigFile the File to write the Docker client configuration to.
    * @param credentials the populated Credentials object.
    * @throws IOException if the write fails.
+   * @return true if a Docker credential is found in the supplied credentials.
    */
-  public static void writeDockerCredentialsToPath(File outConfigFile,
+  public static boolean writeDockerCredentialsToPath(File outConfigFile,
       Credentials credentials) throws IOException {
-    ObjectMapper mapper = new ObjectMapper();
-    ObjectNode rootNode = mapper.createObjectNode();
-    ObjectNode registryUrlNode = mapper.createObjectNode();
     boolean foundDockerCred = false;
     if (credentials.numberOfTokens() > 0) {
+      ObjectMapper mapper = new ObjectMapper();
+      ObjectNode rootNode = mapper.createObjectNode();
+      ObjectNode registryUrlNode = mapper.createObjectNode();
       for (Token<? extends TokenIdentifier> tk : credentials.getAllTokens()) {
         if (tk.getKind().equals(DockerCredentialTokenIdentifier.KIND)) {
           foundDockerCred = true;
@@ -176,12 +177,14 @@ public final class DockerClientConfigHandler {
           }
         }
       }
+      if (foundDockerCred) {
+        rootNode.put(CONFIG_AUTHS_KEY, registryUrlNode);
+        String json = mapper.writerWithDefaultPrettyPrinter()
+            .writeValueAsString(rootNode);
+        FileUtils.writeStringToFile(
+            outConfigFile, json, StandardCharsets.UTF_8);
+      }
     }
-    if (foundDockerCred) {
-      rootNode.put(CONFIG_AUTHS_KEY, registryUrlNode);
-      String json =
-          mapper.writerWithDefaultPrettyPrinter().writeValueAsString(rootNode);
-      FileUtils.writeStringToFile(outConfigFile, json, StandardCharsets.UTF_8);
-    }
+    return foundDockerCred;
   }
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/test/java/org/apache/hadoop/yarn/security/TestDockerClientConfigHandler.java

@@ -116,8 +116,8 @@ public class TestDockerClientConfigHandler {
     Credentials credentials =
         DockerClientConfigHandler.readCredentialsFromConfigFile(
             new Path(file.toURI()), conf, APPLICATION_ID);
-    DockerClientConfigHandler.writeDockerCredentialsToPath(outFile,
-        credentials);
+    assertTrue(DockerClientConfigHandler.writeDockerCredentialsToPath(outFile,
+        credentials));
     assertTrue(outFile.exists());
     String fileContents = FileUtils.readFileToString(outFile);
     assertTrue(fileContents.contains("auths"));

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/runtime/DockerLinuxContainerRuntime.java

@@ -1299,14 +1299,15 @@ public class DockerLinuxContainerRuntime implements LinuxContainerRuntime {
                   .getParent();
           File dockerConfigPath = new File(nmPrivateDir + "/config.json");
           try {
-            DockerClientConfigHandler
-                .writeDockerCredentialsToPath(dockerConfigPath, credentials);
+            if (DockerClientConfigHandler
+                .writeDockerCredentialsToPath(dockerConfigPath, credentials)) {
+              dockerRunCommand.setClientConfigDir(dockerConfigPath.getParent());
+            }
           } catch (IOException e) {
             throw new ContainerExecutionException(
                 "Unable to write Docker client credentials to "
                     + dockerConfigPath);
           }
-          dockerRunCommand.setClientConfigDir(dockerConfigPath.getParent());
         }
       }
     }