Amplify Storage S3 bucket public policy

s3-cloudformation-template.json

"S3BucketPolicy": {
  "Type": "AWS::S3::BucketPolicy",
  "Properties": {
    "Bucket": {
      "Fn::Join": [
        "",
        [
          { "Ref": "bucketName" },
          {
            "Fn::Select": [
              3,
              {
                "Fn::Split": [
                  "-",
                  {
                    "Ref": "AWS::StackName"
                  }
                ]
              }
            ]
          },
          "-",
          {
            "Ref": "env"
          }
        ]
      ]
    },
    "PolicyDocument": {
      "Statement": [
        {
          "Sid": "PublidReadGetObject",
          "Effect": "Allow",
          "Action": "s3:GetObject",
          "Principal": "*",
          "Resource": {
            "Fn::Join": [
              "",
              [
                "arn:aws:s3:::",
                { "Ref": "bucketName" },
                {
                  "Fn::Select": [
                    3,
                    {
                      "Fn::Split": [
                        "-",
                        {
                          "Ref": "AWS::StackName"
                        }
                      ]
                    }
                  ]
                },
                "-",
                {
                  "Ref": "env"
                },
                "/*"
              ]
            ]
          }
        }
      ]
    }
  }
},