带有Java的AWS Lambda抛出由ClassNotFoundException引起的NoClassDefFoundError，该异常未在本地抛出

Question

I've recently started playing around with AWS Lambda with Java.

It has been going well, until I started using Dagger 2 for injection.

Now Lambda throws the following error:

{
  "errorMessage": "dagger/internal/Preconditions",
  "errorType": "java.lang.NoClassDefFoundError",
  "stackTrace": [
    "com.company.server.user.SignUpActionAws.handler(SignUpActionAws.java:27)",
    "sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)",
    "sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)",
    "sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)",
    "java.lang.reflect.Method.invoke(Method.java:498)"
  ],
  "cause": {
    "errorMessage": "dagger.internal.Preconditions",
    "errorType": "java.lang.ClassNotFoundException",
    "stackTrace": [
      "java.net.URLClassLoader.findClass(URLClassLoader.java:381)",
      "java.lang.ClassLoader.loadClass(ClassLoader.java:424)",
      "java.lang.ClassLoader.loadClass(ClassLoader.java:357)",
      "com.company.server.user.SignUpActionAws.handler(SignUpActionAws.java:27)",
      "sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)",
      "sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)",
      "sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)",
      "java.lang.reflect.Method.invoke(Method.java:498)"
    ]
  }
}

However, this does not occur when running java -jar myjar.jar locally. I've also checked that the class is in there using jar tvf myjar.jar .

I build using Bazel.

Other questions I've checked have suggested that it might be due to a dependency not being available, however, the contents of the class has no dependencies.

Taken from the Dagger repo :

/*
 * Copyright (C) 2016 Google, 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 dagger.internal;

/**
 * An adaptation of Guava's {@code com.google.common.base.Preconditions} that is specially tailored
 * to support checks applied in Dagger's generated code.
 */
public final class Preconditions {
  /**
   * Ensures that an object reference passed as a parameter to the calling method is not null.
   *
   * @param reference an object reference
   * @return the non-null reference that was validated
   * @throws NullPointerException if {@code reference} is null
   */
  public static <T> T checkNotNull(T reference) {
    if (reference == null) {
      throw new NullPointerException();
    }
    return reference;
  }

  /**
   * Ensures that an object reference passed as a parameter to the calling method is not null.
   *
   * @param reference an object reference
   * @param errorMessage the exception message to use if the check fails
   * @return the non-null reference that was validated
   * @throws NullPointerException if {@code reference} is null
   */
  public static <T> T checkNotNull(T reference, String errorMessage) {
    if (reference == null) {
      throw new NullPointerException(errorMessage);
    }
    return reference;
  }

  private Preconditions() {}
}

What might be causing the issue on AWS that doesn't occur on my local environment when running a self-contained jar?

Thanks in advance

Edit 1: Here is the minimal BUILD file:

java_binary(
  name = "bin",
  srcs = glob(["Action.java"]),
  main_class = "com.company.Action",
  deps = [
    "//external:aws-lambda",
    "//external:dagger",
  ]
)

Here is the WORKSPACE file:

bind(name = "aws-lambda", actual = "@com_amazonaws_aws_lambda_java_core//jar")
maven_jar(
  name = "com_amazonaws_aws_lambda_java_core",
  artifact = "com.amazonaws:aws-lambda-java-core:1.1.0"
)
bind(name = "dagger", actual = "@com_google_dagger//jar")
maven_jar(
  name = "com_google_dagger",
  artifact = "com.google.dagger:dagger:2.5",
)

Here is Action.java (note, I use Preconditions directly to make it the minimal implementation, in my actual code it fails when trying to build a component):

package com.company;

import com.amazonaws.services.lambda.runtime.Context;

public class Action {
  public static void main(String[] s) {
    Action.handler(null, null);
  }

  public static String handler(String request, Context context) {
    dagger.internal.Preconditions.checkNotNull(new Object(), "Test");
    return null;
  }
}

If you run bazel build //src/main/com/company:bin_deploy.jar and upload it to an AWS Lambda function, it should fail. If you locally run bazel run //src/main/com/company:bin or java -jar bazel-bin/src/main/com/company/bin_deploy.jar it will work fine.

Answer 1

It was all due to permissions in the dagger folder inside of my jar. All the other folders (eg com, org, mozilla) had 755, but not the dagger folder. I unzipped my jar, ran two commands to convert the directories to 755 and the files to 644, then I zipped it back up.

The commands for changing the permissions:

From inside the unzipped directory:
find . -type f -exec chmod 644 {} +
find . -type d -exec chmod 755 {} +

I don't know why it is different to the other directories when Bazel is building it. But that is the problem.

---

For future Bazel searchers, here is the genrule I'm now using:

genrule(
  name = "target-aws",
  srcs = ["target_deploy.jar"],
  outs = ["target-aws.jar"],
  cmd = """
  unzip -q $< -d t
  cd t
  find . -type f -exec chmod 644 {} +
  find . -type d -exec chmod 755 {} +
  zip ../$@ -q -r .
  rm -rf t
  """
)