Write an AWS Lambda to query a Neptune DB with openCypher using aws-sdk v3

I have a Lambda with Node.js 18 runtime, in which I would like to send an openCypher query to an AWS Neptune DB.
My Lambda is using an IAM role with these policies:

NeptuneFullAccess
AWSLambdaBasicExecutionRole
AmazonSSMReadOnlyAccess

(The last policy will be used to fetch the Neptune endpoint from the SSM parameters store later).

I'm trying to find the aws-sdk/client-neptune method to submit the query, but I couldn't find any in the library @ GitHub.

This is frustrating, as I'm struggling for days to find a simple way to use the aws-sdk V3 with a Nodejs 18 Lambda to do a simple task of querying the Neptune DB.

Here my current skeleton of the Lambda:

import { NeptuneClient } from "@aws-sdk/client-neptune";

export async function handler() {
    
    const neptuneEndpoint = "https://<my-db-instance>.us-east-1.neptune.amazonaws.com";
  
    const neptune = new NeptuneClient({
        endpoint: neptuneEndpoint,
        region: "us-east-1",
    });

    const cypher = `MATCH (n) RETURN n`;
    const query = {
        Gremlin: cypher
    };

    const command = {
        GremlinCommand: query,
    };
    
    const result = await neptune.send(command).promise();
    console.log(result);
    return result;
}

Can anyone please help me turn this into a working Lambda?

The client you are using only exposes Control Plane actions, such as Creating/Modifying cluster instances, and is not meant to be used to query Neptune. For openCypher, the recommendation is to query Neptune using the HTTPS endpoint as described here.

I have created a sample Neptune db and sample lambda. I have also used Lambda layers to install necessary gremlin dependencies. Please find the lambda code and lambda response screenshots below

Lambda code

const gremlin = require('gremlin');
const DriverRemoteConnection = gremlin.driver.DriverRemoteConnection;
const Graph = gremlin.structure.Graph;

dc = new DriverRemoteConnection('wss://<db cluster name>.ap-south-1.neptune.amazonaws.com:8182/gremlin',{});

const graph = new Graph();
const g = graph.traversal().withRemote(dc);
    const { t: { id } } = gremlin.process;
    const { cardinality: { single } } = gremlin.process;
    
    const createVertex = async (vertexId, vlabel) => {
      const vertex = await g.addV(vlabel)
        .property(id, vertexId)
        .property(single, 'name', 'lambda')
        .property('lastname', 'Testing') // default database cardinality
        .next();
    
      return vertex.value;
};
createVertex('sampledata1','testing')
exports.handler = async(event) => {

    try {

    const results = await g.V().hasLabel("sampledata1").properties("name")
    console.log("--------",results);
    return  results

    } catch (error) {
      // error handling.
       console.log("---error---",error);
       return error
    }

};

Note:
Replace db endpoint with your own db endpoint

Sample response from lambda

Lambda response screenshot