Create bucket and lambda trigger in same serverless framework - amazon-web-services

Question

I want to create an s3 bucket, and trigger a lambda function whenever some file is uploaded to 'uploads' folder in the bucket. I want to create those resources using serverless framework in aws.
I have defined my s3 bucket configuration in under 'provider.s3', and then I am trying to reference that bucket under functions.hello.events.bucket
However, I am getting following error when i run sls package
Serverless Error ----------------------------------------
MyS3Bucket - Bucket name must conform to pattern (?!^(\d{1,3}\.){3}\d{1,3}$)(^(([a-z0-9]|[a-z0-9][a-z0-9-]*[a-z0-9])\.)*([a-z0-9]|[a-z0-9][a-z0-9-]*[a-z0-9])$). Please check provider.s3.MyS3Bucket and/or s3 events of function "hello".
serverless.yml
service: some-service
frameworkVersion: '2'
useDotenv: true
provider:
name: aws
runtime: python3.8
lambdaHashingVersion: 20201221
s3:
MyS3Bucket:
bucketName: ${env:MY_BUCKET_NAME}
accessControl: Private
lifecycleConfiguration:
Rules:
- Id: ExpireRule
Status: Enabled
ExpirationInDays: '7'
package:
individually: true
functions:
hello:
name: my-lambda-function
handler: function.handler
memorySize: 128
timeout: 900
events:
- s3:
bucket: MyS3Bucket
event: s3:ObjectCreated:*
rules:
- prefix: uploads/
My next try was defining the s3 bucket under 'resources', and using the reference of the bucket in the lambda trigger. I am still getting the warning messages
Serverless: Configuration warning at 'functions.hello.events[0].s3.bucket': should be string
serverless.yml
service: some-service
frameworkVersion: '2'
useDotenv: true
provider:
name: aws
runtime: python3.8
lambdaHashingVersion: 20201221
package:
individually: true
functions:
hello:
name: my-lambda-function
handler: handler.handler
memorySize: 128
timeout: 900
events:
- s3:
bucket:
Ref: MyS3Bucket
event: s3:ObjectCreated:*
rules:
- prefix: uploads/
existing: true
resources:
Resources:
MyS3Bucket:
Type: AWS::S3::Bucket
Properties:
AccessControl: Private
BucketName: 'test.bucket'
OwnershipControls:
Rules:
- ObjectOwnership: ObjectWriter
LifecycleConfiguration:
Rules:
- Id: ExpireRule
Status: Enabled
ExpirationInDays: '7'

Answer 1

You should use your bucket name, not MyS3Bucket:
events:
- s3:
bucket: ${env:MY_BUCKET_NAME}

Answer 2

Create a custom s3 bucket name variable e.g.
custom:
bucket: foo-thumbnails
And use it events
events:
- s3:
bucket: ${self:custom.bucket}