Unresolved resource dependencies [arn:aws:s3:::alberto313131/*] in the Resources block of the template

Question

I am getting the error above when trying to create a AWS CloudFormation script through the console designer. I am certain that the bucket alberto313131 exists.

Here is the full error:

Template contains errors.: Template format error: Unresolved resource dependencies [arn:aws:s3:::alberto313131/*] in the Resources block of the template

This is the full script, I am using:

Resources:
  S3BP1KK1X:
    Type: 'AWS::S3::BucketPolicy'
    Properties:
      Bucket: 
        Ref: "arn:aws:s3:::alberto313131/*"
      PolicyDocument: 
        Statement:
          - Sid: AddPerm
            Effect: Allow
            Principal: '*'
            Action:
              - "s3:GetObject"
            Resource:
              - "arn:aws:s3:::alberto313131/*"

Answer 1

I was able to get past my issue using the logical id.

Resources:
  resbucket:
    Type: "AWS::S3::Bucket"
    Properties: 
      BucketName: "testathena44"
  resbucketpolicy:
    Type: "AWS::S3::BucketPolicy"
    Properties:
      Bucket: !Ref resbucket
      PolicyDocument:
        Statement:
          -
            Sid: "ABC123"
            Action:
              - "s3:GetObject"
            Effect: Allow
            Resource: !Join ["", ["arn:aws:s3:::", !Ref resbucket, "/*"]]
            Principal:
              AWS:
                - "*"

Answer 2

From the CloudFormation S3 BucketPolicy doco

Properties

Bucket

The name of the Amazon S3 bucket to which the policy applies.

So, you simply provide the bucket name, not the ARN.

Only for the Resource inside the Statement section of the PolicyDocument do you provide the ARN.