Creating an AWS Lambda function

In this section, we will create a Lambda function to process Kinesis events.

For a more detailed coverage of this topic, refer to the blog by Sunil Dalal at: https://www.polyglotdeveloper.com/lambda/2017-07-05-Using-Lambda-as-Kinesis-events-processor/. Refer to Creating a .jar Deployment Package Using Maven and Eclipse IDE (Java) for more details: https://docs.aws.amazon.com/lambda/latest/dg/java-create-jar-pkg-maven-and-eclipse.html.

Create a maven project. Create an example package and key in the following Java code in a class (ProcessKinesisEvents):

package example;
import java.io.IOException;
import com.amazonaws.services.lambda.runtime.events.KinesisEvent;
import com.amazonaws.services.lambda.runtime.events.KinesisEvent.KinesisEventRecord;
public class ProcessKinesisEvents {
    public String handleRequest(KinesisEvent event) throws IOException {
       System.out.println("Record Size - " + event.getRecords().size());
       for(KinesisEventRecord rec : event.getRecords()) {
         System.out.println(new             String(rec.getKinesis().getSequenceNumber()));
         System.out.println(new String(rec.getKinesis().getData().array()));
       }
       return "success";
    }
}

The pom.xml file is listed as follows for reference:

<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>
<description>AWS Lambda Java Example</description>
<dependencies>
  <dependency>
      <groupId>com.amazonaws</groupId>
      <artifactId>aws-lambda-java-core</artifactId>
      <version>1.1.0</version>
  </dependency>
  <dependency>
      <groupId>com.amazonaws</groupId>
      <artifactId>aws-lambda-java-events</artifactId>
      <version>1.3.0</version>
  </dependency>
</dependencies>
<build>
  <plugins>
      <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-shade-plugin</artifactId>
          <version>2.3</version>
      </plugin>
  </plugins>
</build>
</project>

Select Lambda from the IAM console:

Search for AWSLambdaKinesisExecutionRole and attach the permissions policy to the AWS Lambda role:

Use the create-function command as shown to create the Lambda function:

aws lambda create-function 
>  --region us-west-2 
>  --function-name ProcessKinesisEvents 
>  --zip-file fileb:///Users/aurobindosarkar/Downloads/IWebApps/workspace/lambda-java-example/target/lambda-java-example-0.0.1-SNAPSHOT.jar 
>  --role arn:aws:iam::450394462648:role/lambda-kinesis-execution-role 
>  --handler example.ProcessKinesisEvents::handleRequest 
>  --runtime java8
{
    "TracingConfig": {
        "Mode": "PassThrough"
    }, 
    "CodeSha256": "jQQ9jo18W57ngH7HFDDv4S0DF9EYNFkYs2NoUQBFz1Q=", 
    "FunctionName": "ProcessKinesisEvents", 
    "CodeSize": 7763705, 
    "MemorySize": 128, 
    "FunctionArn": "arn:aws:lambda:us-west-2:450394462648:function:ProcessKinesisEvents", 
    "Version": "$LATEST", 
    "Role": "arn:aws:iam::450394462648:role/lambda-kinesis-execution-role", 
    "Timeout": 3, 
    "LastModified": "2018-01-28T18:52:25.963+0000", 
    "Handler": "example.ProcessKinesisEvents::handleRequest", 
    "Runtime": "java8", 
    "Description": ""
}

The newly created function will be listed in the Lambda Functions console:

Create an input file (input.txt) with the following records to test the Lambda function:

{
   "Records": [
       {
           "kinesis": {
               "partitionKey": "partitionKey-3",
               "kinesisSchemaVersion": "1.0",
               "data": "SGVsbG8sIHRoaXMgaXMgYSB0ZXN0IDEyMy4=",
               "sequenceNumber": "49545115243490985018280067714973144582180062593244200961"
           },
           "eventSource": "aws:kinesis",
           "eventID": "shardId-000000000000:49545115243490985018280067714973144582180062593244200961",
           "invokeIdentityArn": "arn:aws:iam::account-id:role/testLEBRole",
           "eventVersion": "1.0",
           "eventName": "aws:kinesis:record",
           "eventSourceARN": "arn:aws:kinesis:us-west-2:35667example:stream/examplestream",
           "awsRegion": "us-west-2"
       }
   ]
}

Invoke the Lambda function. Specify the invocation-type as Event, function name as ProcessKinesisEvents, region, input, and output files as shown:

Aurobindos-MacBook-Pro-2:Downloads aurobindosarkar$ aws lambda invoke 
> --invocation-type Event 
> --function-name ProcessKinesisEvents 
> --region us-west-2 
> --payload file:///Users/aurobindosarkar/Downloads/input.txt 
> outputfile.txt

For a synchronous response, specify invocation-type as RequestResponse in the preceding command.
Add an event source in AWS Lambda so that your Lambda function can start polling the Amazon Kinesis stream:

Aurobindos-MacBook-Pro-2:Downloads aurobindosarkar$ aws lambda create-event-source-mapping 
> --region us-west-2 
> --function-name ProcessKinesisEvents 
> --event-source arn:aws:kinesis:us-west-2:450394462648:stream/KinesisTestStream 
> --batch-size 100 
> --starting-position TRIM_HORIZON

Using the following AWS CLI command, add event records to your Amazon Kinesis stream. You can run the same command more than once to add multiple records to the stream:

Aurobindos-MacBook-Pro-2:Downloads aurobindosarkar$ aws kinesis put-record 
> --stream-name KinesisTestStream 
> --data “Test Record 1” 
> --partition-key shardId-000000000000 
> --region us-west-2

Validate that the Lambda function and process the records by going to CloudWatch logs:

Aurobindos-MacBook-Pro-2:Downloads aurobindosarkar$ aws logs describe-log-streams --log-group-name '/aws/lambda/ProcessKinesisEvents' --region us-west-2 --order-by LastEventTime --descending

Table of Contents for Creating an AWS Lambda function

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Table of Contents for
Creating an AWS Lambda function