Serverless deployment, UnknownEndpoint: Inaccessible host

Question

I am trying to deploy the python serverless application on AWS.

I follow pretty straightforward tutorial and I do following steps:

1. Install serverless npm install -g serverless
2. Generate template project sls create --template aws-python3 --name sls-demo --path sls-demo

My handler.py file looks as follows:

import json


def hello(event, context):
    body = {
        "message": "Go Serverless v1.0! Your function executed successfully!",
        "input": event
    }

    response = {
        "statusCode": 200,
        "body": json.dumps(body)
    }

    return response

And my serverless.yml configuration file looks as follows:

service: sls-demo
frameworkVersion: '2'

provider:
  name: aws
  runtime: python3.8
  lambdaHashingVersion: 20201221
  region: eu-central-1

functions:
  hello:
    handler: handler.hello

I have already installed aws cli on my machine, configured it with aws credentials and when I run the deployment command sls deploy it finishes successfully.

I test the lambda function with following command sls invoke --function hello and the result returns successfully:

{
    "statusCode": 200,
    "body": "{\"message\": \"Go Serverless v1.0! Your function executed successfully!\", \"input\": {}}"
}

Now I want to introduce some extra dependencies in my lambda function, dockerize it and deploy using the serverless-python-requirements plugin.

For this I do following steps:

1. Create virtual environment python -m venv ./venv
2. Activate virtual environment source venv/bin/activate
3. Install numpy dependency pip install numpy
4. Freeze python dependencies pip freeze > requirements.txt
5. Install serverless-python-requirements plugin sls plugin install -n serverless-python-requirements

My updated handler.py file looks as follows:

import json
import numpy


def hello(event, context):
    array = numpy.arange(15).reshape(3, 5)

    body = {
        "message": "Go Serverless v1.0! Your function executed successfully!",
        "input": event,
        "array": array
    }

    response = {
        "statusCode": 200,
        "body": json.dumps(body)
    }

    return response

And my updated serverless.yml configuration file looks as follows:

service: sls-demo
frameworkVersion: '2'

provider:
  name: aws
  runtime: python3.8
  lambdaHashingVersion: 20201221
  region: eu-central-1

functions:
  hello:
    handler: handler.hello

plugins:
  - serverless-python-requirements

custom:
  pythonRequirements:
    dockerizePip: non-linux

After these changes, when I run the deployment command sls deploy it fails with the following error:

Serverless: Recoverable error occurred (Inaccessible host: `sls-demo-dev-serverlessdeploymentbucket-xyz.s3.eu-central-1.amazonaws.com'. This service may not be available in the `eu-central-1' region.), sleeping for ~5 seconds. Try 1 of 4

I enabled debug logs for the serverless by exporting this flag export SLS_DEBUG=* and the exception stack trace looks as follows:

Serverless: Recoverable error occurred (UnknownEndpoint: Inaccessible host: `sls-demo-dev-serverlessdeploymentbucket-xyz.s3.eu-central-1.amazonaws.com'. This service may not be available in the `eu-central-1' region.
    at Request.ENOTFOUND_ERROR (/Users/macbook/.nvm/versions/node/v14.16.0/lib/node_modules/serverless/node_modules/aws-sdk/lib/event_listeners.js:507:46)
    at Request.callListeners (/Users/macbook/.nvm/versions/node/v14.16.0/lib/node_modules/serverless/node_modules/aws-sdk/lib/sequential_executor.js:106:20)
    at Request.emit (/Users/macbook/.nvm/versions/node/v14.16.0/lib/node_modules/serverless/node_modules/aws-sdk/lib/sequential_executor.js:78:10)
    at Request.emit (/Users/macbook/.nvm/versions/node/v14.16.0/lib/node_modules/serverless/node_modules/aws-sdk/lib/request.js:688:14)
    at ClientRequest.error (/Users/macbook/.nvm/versions/node/v14.16.0/lib/node_modules/serverless/node_modules/aws-sdk/lib/event_listeners.js:339:22)
    at ClientRequest.<anonymous> (/Users/macbook/.nvm/versions/node/v14.16.0/lib/node_modules/serverless/node_modules/aws-sdk/lib/http/node.js:96:19)
    at ClientRequest.emit (events.js:315:20)
    at ClientRequest.EventEmitter.emit (domain.js:467:12)
    at TLSSocket.socketErrorListener (_http_client.js:469:9)
    at TLSSocket.emit (events.js:315:20)
    at TLSSocket.EventEmitter.emit (domain.js:467:12)
    at emitErrorNT (internal/streams/destroy.js:106:8)
    at emitErrorCloseNT (internal/streams/destroy.js:74:3)
    at processTicksAndRejections (internal/process/task_queues.js:80:21)
----------------------------------------------------------------------------------------------------), sleeping for ~7 seconds. Try 1 of 4

This error happens when serverless is trying to upload the build artifact to the s3 bucket:

Serverless: Uploading service sls-demo.zip file to S3 (33.14 MB)...

I suspect that this error happens due to the large size of the file, but I don't know how to resolve this problem, or if I miss something in the configuration.

I tried to upload the large file in the mentioned s3 bucket using the aws cli and it works without any problem:

aws s3 cp large_file.zip s3://sls-demo-dev-serverlessdeploymentbucket-xyz/large_file.zip

I don't know how to troubleshoot this problem, and I was unable to find any answer regarding this error in the internet. Any help appreciated.