I'm creating a bucket and a bucket policy using Pulumi / Python. How to get the bucket arn from a bucket resource for creating the bucket policy? If I try to get the bucket arn in the same pulumi up run (i.e. creating the bucket and bucket policy) I get required field is not set. If I try to get the id from the bucket I just get the Output object - how to convert that to string?

Is the

arn

always

arn:aws:s3:::bucket_name

?

You do need to apply the arn if you're building out the entire bucket policy json. Here's an example - https://github.com/pulumi/examples/blob/ec43670866809bfd64d3a39f68451f957d3c1e1d/aws-py-s3-folder/__main__.py#L21-L39.

I found a way to do it yesterday:

policy = bucket.id.apply(lambda id:
            '''
            {{
...
               "Resource": "arn:aws:s3:::{my_id}/*"
...
'''.format(my_id=id)...