Amazon Web Service Lambda using Java

Question

Hi I am doing a small POC with AWS Lambda using Java,
I want to test a simple Lambda function call, which will accept a string
I am using Google's Gson to convert String to Json and use it in my demo program.

I referred this documentation for my demo -
http://docs.aws.amazon.com/lambda/latest/dg/get-started-step4-optional.html and
http://docs.aws.amazon.com/lambda/latest/dg/java-create-jar-pkg-maven-and-eclipse.html

Here's my Project directory structure -

I am getting an error when I call the Lambda function with the following String -

"{'name':'Aniruddha','age':'25'}"

Here's the error -

{
  "errorMessage": "com/google/gson/GsonBuilder",
  "errorType": "java.lang.NoClassDefFoundError",
  "stackTrace": [
    "example.Hello.myHandler(Hello.java:11)",
    "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)"
  ]
}

Here's my Handler function -

package example;

import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.LambdaLogger;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class Hello {
    public String myHandler(String request, Context context) {

        GsonBuilder builder = new GsonBuilder();
        Gson gson = builder.create();

        QueryParams queryParams = gson.fromJson(request, QueryParams.class);
        System.out.println("Name is: "+queryParams.getName()+" Age is: "+queryParams.getAge());

        LambdaLogger logger = context.getLogger();
        logger.log("received a Lambda request");

        String message = "Hey there! " + queryParams.getName() + " you are " + queryParams.getAge() + " years old";
        return message;
    }
}

This is my PoJo -

package example;

public class QueryParams {

    String name;
    int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

}

This is the pom.xml -

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>doc-examples</groupId>
  <artifactId>lambda-java-example</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>lambda-java-example</name>
  <dependencies>
        <!-- https://mvnrepository.com/artifact/com.amazonaws/aws-lambda-java-core -->
        <dependency>
            <groupId>com.amazonaws</groupId>
            <artifactId>aws-lambda-java-core</artifactId>
            <version>1.0.0</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>1.4</version>
        </dependency>       
   </dependencies>
     <build>
       <plugins>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-shade-plugin</artifactId>
           <version>2.3</version>
           <configuration>
             <createDependencyReducedPom>false</createDependencyReducedPom>
           </configuration>
           <executions>
             <execution>
               <phase>package</phase>
               <goals>
                 <goal>shade</goal>
               </goals>
             </execution>
           </executions>
         </plugin>
       </plugins>
     </build>
</project>

Don't know AWS, but it looks like GSON is not on the classpath. Perhaps you forgot to deploy it with your code? Or were you expecting it to already be there? — Andreas
@Andreas sorry I'm new to Java, can you tell me what to do? I did a clean and build and then did a Maven install to get the Jar, did I miss anyting? — Ani
It doesn't seem like you have followed the steps described in the dicumentaton to create your packege: docs.aws.amazon.com/lambda/latest/dg/… — JB Nizet
There is no maven shade plugin in your pom. So you haven't followed the steps until the end. The mven shade plugin is what allows building a jar containing not only your code, but all the dependencies (Gson in this case) that your code needs. — JB Nizet

Ani Ani · Accepted Answer · 2016-11-20T10:09:59

Alright as @JBNizet advised (check question's comments), It solved the issue.
Here's the pom.xml we need -

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>doc-examples</groupId>
  <artifactId>lambda-java-example</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>lambda-java-example</name>
  <dependencies>
        <!-- https://mvnrepository.com/artifact/com.amazonaws/aws-lambda-java-core -->
        <dependency>
            <groupId>com.amazonaws</groupId>
            <artifactId>aws-lambda-java-core</artifactId>
            <version>1.0.0</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>1.4</version>
        </dependency>       
   </dependencies>
     <build>
       <plugins>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-shade-plugin</artifactId>
           <version>2.3</version>
           <configuration>
             <createDependencyReducedPom>false</createDependencyReducedPom>
           </configuration>
           <executions>
             <execution>
               <phase>package</phase>
               <goals>
                 <goal>shade</goal>
               </goals>
             </execution>
           </executions>
         </plugin>
       </plugins>
     </build>
</project>

Amazon Web Service Lambda using Java

1 Answers