How to split a serverless configuration file?

I'm trying to split my serverless configuration file serverless.yml into multiple files using the ${file(...)} syntax. I have a provider file config/serverless/provider.yml with the following content:

provider:
  name: ...
  ...

And in my serverless.yml I've used it in the following way:

provider: ${file(config/serverless/provider.yml):provider}

However, when I run serverless deploy, I get the following error:

Cannot resolve serverless.yml: Variables resolution errored with:
  - Cannot resolve variable at "provider": Value not found at "file"

Please help me to understand how to properly include other files in my serverless configuration.

NOTE: I've also tried with this config without success

provider.yml

name: ...
...

serverless.yml

...
resources:
  - ${file(config/serverless/provider.yml)}

Cannot resolve serverless.yml: Variables resolution errored with:
  - Cannot resolve variable at "provider": Value not found at "file"

The error is not finding a value at "file" double check the file path.

Make sure the path you are using in ${file(<this-path-here>):provider}

It is pointing to the correct file.

The following works:

• File: serverless.yml

service: serverless-framework-include-files
frameworkVersion: "3"

provider: ${file(config/provider.yml):provider}

functions:
  function1:
    handler: index.handler

• File: config/provider.yml

provider:
  name: aws
  runtime: nodejs18.x

Alternatively, you can remove the :provider from the ${file(...):provider}:

The following works:

• File: serverless2.yml

service: serverless-framework-include-files
frameworkVersion: "3"

provider: ${file(config/provider2.yml)}

functions:
  function1:
    handler: index.handler

• File: config/provider2.yml

name: aws
runtime: nodejs18.x

For resources:, the same applies.

This works:

• File: serverless.yml

resources:
 - ${file(resources/s3-bucket.yml)}
 - ${file(resources/dynamodb-table.yml)}

• File: resources/s3-bucket.yml

Resources:
  MyBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: my-bucket
      AccessControl: PublicRead
      WebsiteConfiguration:
        IndexDocument: index.html
        ErrorDocument: error.html

Alternatively, you can do:

• File serverless2.yml

resources:
  Resources:
    MyBucket: ${file(resources/s3-bucket2.yml)}
    MyTable: ${file(resources/dynamodb-table2.yml)}

• File resources/dynamodb-table2.yml

Type: AWS::DynamoDB::Table
Properties:
  TableName: ${self:service}
  AttributeDefinitions:
    - AttributeName: id
      AttributeType: S
  KeySchema:
    - AttributeName: id
      KeyType: HASH
  ProvisionedThroughput:
    ReadCapacityUnits: 1
    WriteCapacityUnits: 1

You can check the GitHub code for a working example:

• https://github.com/oieduardorabelo/serverless-framework-include-files