This commit enables the ability to authenticate to OpenStack by way
of a Keystone Token. Tokens can provide a way to use Terraform and
OpenStack with an expiring, temporary credential. The token will need
to be generated out of band from Terraform.
Official OpenStack clients support specifing custom CA certificate file
that should be used when communicating with OpenStack server. This patch
adds similar behavior to Terraform OpenStack provider, by:
- Using OS_CACERT environmental variable, if available
- Using cacert_file provider parameter, if configured
Joe Topjian