How to pass region as query param for aws java lambda function

Question

I'm new to AWS lambda. I'm creating ec2 instance using AWS java Lambda function in which i'm trying to pass the region dynamically using API gateway.

I'm passing the region as queryparamstring. I'm not sure how to get the queryparam inside the lambda function. I have gone through the questions asked similar to this but unable to understand how to implement that.

Please find the below java lambda function:

package com.amazonaws.lambda.demo;

    import java.util.List;

    import org.json.simple.JSONObject;

    import com.amazonaws.auth.AWSCredentials;
    import com.amazonaws.auth.AWSStaticCredentialsProvider;
    import com.amazonaws.auth.BasicAWSCredentials;
    import com.amazonaws.regions.Regions;
    import com.amazonaws.services.ec2.AmazonEC2;
    import com.amazonaws.services.ec2.AmazonEC2ClientBuilder;
    import com.amazonaws.services.ec2.model.CreateTagsRequest;
    import com.amazonaws.services.ec2.model.DescribeInstanceStatusRequest;
    import com.amazonaws.services.ec2.model.DescribeInstanceStatusResult;
    import com.amazonaws.services.ec2.model.Instance;
    import com.amazonaws.services.ec2.model.InstanceNetworkInterfaceSpecification;
    import com.amazonaws.services.ec2.model.InstanceStatus;
    import com.amazonaws.services.ec2.model.RunInstancesRequest;
    import com.amazonaws.services.ec2.model.RunInstancesResult;
    import com.amazonaws.services.ec2.model.StartInstancesRequest;
    import com.amazonaws.services.ec2.model.Tag;
    import com.amazonaws.services.lambda.runtime.Context;
    import com.amazonaws.services.lambda.runtime.RequestHandler;
    import com.amazonaws.services.lambda.runtime.events.S3Event;
    import com.amazonaws.services.s3.AmazonS3;
    import com.amazonaws.services.s3.AmazonS3ClientBuilder;


    public class LambdaFunctionHandler implements RequestHandler<S3Event, String> {
         private static final AWSCredentials AWS_CREDENTIALS;
            static String ACCESS_KEY="XXXXXXXXXX";
            static String SECRET_KEY="XXXXXXXXXXXXXXXX";

            static {
                // Your accesskey and secretkey
                AWS_CREDENTIALS = new BasicAWSCredentials(
                        ACCESS_KEY,
                        SECRET_KEY
                );
            }
        private AmazonS3 s3 = AmazonS3ClientBuilder.standard().build();

        public LambdaFunctionHandler() {}

        // Test purpose only.
        LambdaFunctionHandler(AmazonS3 s3) {
            this.s3 = s3;
        }


        @Override
        public String handleRequest(S3Event event, Context context) {
            context.getLogger().log("Received event: " + event);


            // Set up the amazon ec2 client
            AmazonEC2 ec2Client = AmazonEC2ClientBuilder.standard()
                    .withCredentials(new AWSStaticCredentialsProvider(AWS_CREDENTIALS))
                    .withRegion(Regions.EU_CENTRAL_1)
                    .build();

            // Launch an Amazon EC2 Instance
            RunInstancesRequest runInstancesRequest = new RunInstancesRequest().withImageId("ami-XXXX")
                    .withInstanceType("t2.micro") // https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-types.html
                    .withMinCount(1)
                    .withMaxCount(1)
                    .withKeyName("KEY")
                    .withNetworkInterfaces(new InstanceNetworkInterfaceSpecification()
                            .withAssociatePublicIpAddress(true)
                            .withDeviceIndex(0)
                            .withSubnetId("subnet-XXX")
                            .withGroups("sg-XXXX"));

            RunInstancesResult runInstancesResult = ec2Client.runInstances(runInstancesRequest);

            Instance instance = runInstancesResult.getReservation().getInstances().get(0);
            String instanceId = instance.getInstanceId();
            String instanceip=instance.getPublicIpAddress();

            System.out.println("EC2 Instance Id: " + instanceId);

            // Setting up the tags for the instance
            CreateTagsRequest createTagsRequest = new CreateTagsRequest()
                    .withResources(instance.getInstanceId())
                    .withTags(new Tag("Name", "SampleLambdaEc2"));
            ec2Client.createTags(createTagsRequest);

            // Starting the Instance
            StartInstancesRequest startInstancesRequest = new StartInstancesRequest().withInstanceIds(instanceId);

            ec2Client.startInstances(startInstancesRequest);




        /*// Stopping the Instance

            StopInstancesRequest stopInstancesRequest = new StopInstancesRequest()
                      .withInstanceIds(instanceId);

                    ec2Client.stopInstances(stopInstancesRequest);*/

            //describing the instance
            DescribeInstanceStatusRequest describeInstanceRequest = new DescribeInstanceStatusRequest().withInstanceIds(instanceId);
            DescribeInstanceStatusResult describeInstanceResult = ec2Client.describeInstanceStatus(describeInstanceRequest);




           List<InstanceStatus> state = describeInstanceResult.getInstanceStatuses();
           while (state.size() < 1) { 
               // Do nothing, just wait, have thread sleep if needed
               describeInstanceResult = ec2Client.describeInstanceStatus(describeInstanceRequest);
               state = describeInstanceResult.getInstanceStatuses();
           }
           String status = state.get(0).getInstanceState().getName();

           System.out.println("status"+status);
           JSONObject response=new JSONObject();

           response.put("instanceip", instanceip);
           response.put("instancestatus", status);

           System.out.println("response=>"+response);


        return response.toString();
        }
    }

I would like to pass the query param instead of Regions.EU_CENTRAL_1

// Set up the amazon ec2 client
            AmazonEC2 ec2Client = AmazonEC2ClientBuilder.standard()
                    .withCredentials(new AWSStaticCredentialsProvider(AWS_CREDENTIALS))
                    .withRegion(Regions.EU_CENTRAL_1)
                    .build();

Please find the API configuration below:

Any advise on how to achieve that would be really helpful. Thanks in advance.

Answer 1

How are you?

If you want to get those query parameters, you may want to use Lambda Proxy Integration.

That way, you will get to you function an APIGatewayProxyRequestEvent, that you can perform a Map<String, String> getQueryStringParameters() operation.

You'll need to declare your handler like:

public class APIGatewayHandler implements RequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent> {
 /// You cool awesome code here! 
}

That way, your method will look like:

@Override
public APIGatewayProxyResponseEvent handleRequest(APIGatewayProxyRequestEvent event, Context context) {

     Map<String, String> params = event.getQueryStringParameters();
     Optional<String> region = Optional.ofNullable(params.get("region"));
     // Create EC2 instance. You may need to parse that region string to AWS Region object. 
}

Let me know if that works for you!