API Gateway refuses to connect to S3,DynamodB using Localstack and serverless - node.js

Question

I'm developing Localstack application where i need to connect s3 bucket and dynamodB to the API gateway, when i invoke my lambda using command line using
serverless invoke local -f helloagain
it just works fine, but when i invoke it through postman using api gateway e.g. http://localhost:4566/restapis/82wh1mpf11/local/_user_request_/helloagain it gives internal server error.
Read operations on s3 and ddb are working fine, it is getting a tedious task when it comes to dumping the data into these resources.
Sharing my code snippets below
this is docker-compose file
version: "3.1"
services:
localstack:
image: localstack/localstack:latest
environment:
- AWS_DEFAULT_REGION=us-east-1
- EDGE_PORT=4566
- SERVICES=lambda,s3,cloudformation,sts,apigateway,iam,route53
ports:
- "4566-4597:4566-4597"
volumes:
- "${TEMPDIR:-/tmp/localstack}:/temp/localstack"
- "/var/run/docker.sock:/var/run/docker.sock"
this is a serverless.yml
service: localstack-lambda
plugins:
- serverless-localstack
custom:
localstack:
debug: true
stages:
- local
- dev
endpointFile: localstack_endpoints.json
# frameworkVersion: "2"
provider:
name: aws
runtime: nodejs12.x
#functions are pretty important
functions:
hello:
handler: handler.hello
events:
- http:
path: hello
method: any
helloagain:
handler: handler.helloagain
events:
- http:
path: helloagain
method: any
createbucket:
handler: s3handler.createbucket
events:
- http:
path: createbucket
method: any
createDDB:
handler: ddb.createDDB
events:
- http:
path: createDDB
method: any
listTables:
handler: ddb.listTables
events:
- http:
path: listTables
method: any
this is helloagain lambda script
const aws = require('aws-sdk');
const fs = require('fs');
const s3 = new aws.S3({
apiVersion: '2006-03-01',
endpoint: `http://localhost:4566`, // This two lines are
s3ForcePathStyle: true, //only needed for LocalStack.
});
module.exports.helloagain = async (event) => {
const file_buffer = fs.readFileSync("demo2.txt");
const params = {
Bucket: "newbucket",
Key: "demo2.txt",
Body:file_buffer
}
const res = await s3.upload(params).promise();
return {
statusCode: 200,
body: JSON.stringify({
res
})
}
}
i've already checked invoking this lambda through command line that
file demo2.txt already exists
bucket exists
i'm getting this error in the console
localstack.services.awslambda.lambda_executors.InvocationException: Lambda process returned with error. Result: {"errorType":"NetworkingError","errorMessage":"connect ECONNREFUSED 127.0.0.1:4566"}.
and this in the postman