Getting "Could not connect to the endpoint URL" Error with boto3 when deploying in Localstack

Question

I am using Localstack to test my changes in local. My lambda function is supposed to perform putObject and create object in the s3 bucket. The functionality works fine when directly tested with AWS environment. But in Localstack, its not working. I get the below error.

Could not connect to the endpoint URL: "http://localhost:4572/doyouknowme/pokemon.jpeg"     raise EndpointConnectionError(endpoint_url=request.url, error=e)ponset_exceptionlhost:4572/doyouknowme/pokemon.jpeg"

AWS Credentials:

[default]
aws_access_key_id = AKI****************
aws_secret_access_key = gL************************
region = us-east-1

Lambda function code:

import json
import urllib.parse
import boto3
import base64

print('Loading function')
# session = boto3.Session(profile_name='personal')
# s3 = session.client('s3', endpoint_url='http://localhost:4574')

s3 = boto3.client('s3', endpoint_url='http://localhost:4572', region_name='us-east-1')


def lambda_handler(event, context):
    # raise Exception('Something went wrong')
    print("Received event: " + json.dumps(event, indent=2))


    try:
        image_data = base64.b64decode(event['image_data'])
        response = s3.put_object(
            Body=image_data,
            Bucket='doyouknowme',
            Key='pokemon.jpeg',
            ContentType='image/jpeg'
        )

        print(response)
        return response

    except Exception as e:
        print(e)
        # print(
        #     'Error getting object {} from bucket {}. Make sure they exist and your bucket is in the same region as '
        #     'this function.'.format(
        #         key, bucket))
        raise e

I am not sure why the s3 key got appended to the endpoint URL which is accessed by lambda. Appreciate your help to resolve this.

Answer 1

For anyone experiencing this problem: I encountered it when it had boto3 in another Docker trying to access localstack with http://localhost:4566.

I fixed my issue by putting http://host.docker.internal:4566 as my endpoint-url in my boto3 session client.

That, or if you're using docker-compose, have your two docker containers on the same network, making calls possible by calling boto3's container name as the endpoint. (i.e. http://boto3-container:4566)

Hope this helps someone!