Is Swift object storage a requirement?

We're in the process of deploying a private openstack instance but don't have the Swift object storage service available yet. Can juju bootstrap launch a utility instance without swift? I see that the openstack configuration control-bucket is a container id.

The juju openstack provider can also be utilized with the nova/objectstore (s3 equiv) for deployments like these. The object storage requirements are minimal and are used primarily for distribution of charms to machines and some client metadata (ie. not much size, or bandwidth).

https://jujucharms.com/docs/stable/config-openstack

Yes, is required. As you can see, the essential configuration for OpenStack look like this:

  openstack:
    type: openstack
    # Specifies whether the use of a floating IP address is required to give the nodes
    # a public IP address. Some installations assign public IP addresses by default without
    # requiring a floating IP address.
    # use-floating-ip: false
    admin-secret: 13850d1b9786065cadd0f477e8c97cd3
    # Globally unique swift bucket name
    control-bucket: juju-fd6ab8d02393af742bfbe8b9629707ee
    # Usually set via the env variable OS_AUTH_URL, but can be specified here
    # auth-url: https://yourkeystoneurl:443/v2.0/
    # override if your workstation is running a different series to which you are deploying
    # default-series: precise
    # The following are used for userpass authentication (the default)
    auth-mode: userpass
    # Usually set via the env variable OS_USERNAME, but can be specified here
    # username: 
    # Usually set via the env variable OS_PASSWORD, but can be specified here
    # password: 
    # Usually set via the env variable OS_TENANT_NAME, but can be specified here
    # tenant-name: 
    # Usually set via the env variable OS_REGION_NAME, but can be specified here
    # region: 

All the fields without a hash (#) in in the front are required.

Source: https://jujucharms.com/docs/stable/config-openstack

Moreover, a unique bucket name has same restrictions and limitations. See, for example, here, here or here.