Invoking an api inside a aws lambda but getting a null response

Question

I am trying to invoke a rest API inside an API but it is not returning anything. So I am making a simple lambda which returns a JSON but getting a null value as a response.

var https = require('https');
var dt;
exports.handler = async (event, context) => {
      var data = '';

    return new Promise((resolve, reject) => {
      var params = {
                host: "cvwtzygw4a.execute-api.ap-south-1.amazonaws.com",
                path: "/test/first"
                };

        const req = https.request(params, (res) => {
          console.log('STATUS: ' + res.statusCode);
           res.setEncoding('utf8');
           res.o n('data', function(chunk) {
               data += chunk;
             });
         res.on('end', function() {
          console.log("DONE");

          console.log(data);
           dt = JSON.parse(data);
          console.log(dt);
         });


      resolve(dt);
    });

    req.on('error', (e) => {
      reject(e.message);
    });

    // send the request
    req.write('');
    req.end();
 });
};

you can use [request-promise](https://www.npmjs.com/package/request-promise) for invoking API's — AZ_, Jan 03 '20 at 11:01
Does this answer your question? [nodejs - How to promisify http.request? reject got called two times](https://stackoverflow.com/questions/38533580/nodejs-how-to-promisify-http-request-reject-got-called-two-times) — AZ_, Jan 03 '20 at 11:04

score 1 · Accepted Answer · answered Jan 03 '20 at 17:52

You should go through this article to understand how to use NodeJs promises in AWS Lambda. In this, the second solution addresses your use case.

To be specific to your code, I modified to make it very simple using the async/await syntax and the request-promise library.

const request = require('request-promise');
exports.handler = async (event, context) => {
    var data = '';

    try {
        data = await request.get('https://cvwtzygw4a.execute-api.ap-south-1.amazonaws.com/test/first');
        console.log('response received', res);
    } catch (error) {
        console.log('Error', error);
    }
    return data;
};

Following was the output:

START RequestId: 80d75f93-5fa6-1354-c22c-0597beb075e7 Version: $LATEST
2020-01-03T17:51:19.987Z        80d75f93-5fa6-1354-c22c-0597beb075e7    response received {
"basic" : {"name":"John","age":31,"city":"New York"}
}
END RequestId: 80d75f93-5fa6-1354-c22c-0597beb075e7
REPORT RequestId: 80d75f93-5fa6-1354-c22c-0597beb075e7  Init Duration: 907.81 ms        Duration: 1258.54 ms    Billed Duration: 1300 ms        Memory Size: 128 MB       Max Memory Used: 55 MB

"{\n\"basic\" : {\"name\":\"John\",\"age\":31,\"city\":\"New York\"}\n}"

Invoking an api inside a aws lambda but getting a null response

1 Answers1