The constraint in the template is intended to remove confusion by making sure that only the bucket name itself is supplied (i.e. without any prefix). This is because the paths within the bucket are currently fixed and determined at runtime (i.e. the
customizer/<profile name>/<hook directory> bits).
We'll update the error message should the constraint check in a future release to make it clearer what the problem is! Something like "Bucket must begin with s3:// or be left blank. Supply bucket name only without paths."
The default bucket name is per account rather than per cluster and is based on a hash of your AWS account ID; all clusters launched under your account will use the same default bucket name. In order to determine what the bucket name is for your account, you have to launch a cluster so it can be calculated.
Once you've uploaded your scripts to the S3 bucket, customizations are applied to all future clusters. Currently customization profiles are only retrieved when the instance is booted, but we're also looking at ways to apply newly uploaded customizations to an existing cluster for a future release.
Of course you can also preconfigure your own bucket and supply its name to the CFN stack. Note that the Marketplace template only grants access to buckets that start with
alces-flight-, so you'll either need to update the template to reflect your own bucket naming policy, or create an